Antioxidant

Antioxidant action A Ascorbate and atocopherol

Most of our understanding of the action of antioxidants is based on historical discoveries in nutrition research on the action of vitamins E and C essential because they suppress oxidative stress in biological systems. The molecular action of these compounds in biological systems can be explained by the chemistry of free radicals, which has been recently reviewed.56 Figure 26.3 is a summary of key ideas in this area. One important concept is that free radical reactions can be propagated from one chemical entity to another through as many as 20 sequential reactions in addition, oxygen changes the inherent reactivity and damage potential of free radicals in biological systems. Antioxidants such as a-tocopherol are important because they can terminate these reactions. The ability of a-tocopherol to act as a free radical scavenger has been investigated in the bilayer phase in liposomes dispersed in aqueous systems. These studies show that the radical scavenging action of a-tocopherol in...

Other antioxidants

As stated above, the mechanism of the action of ascorbate, a-tocopherol, and nitrones, agents that suppress oxidative damage in biological systems, is complex. Simple mass action free radical trapping in a one-phase system does not explain the action of any of these compounds, and therefore, it is unreasonable to assume that this concept would strictly apply to other potential antioxidants. On the other hand, it is reasonable to expect that agents that suppress oxidative damage in biological systems may limit or abate the oxidative stress associated with environmental stressors. More research is needed in order to understand the mechanism(s) and potential of these and other antioxidants and to examine the validity of the concepts and approaches discussed above.

Biodegradable Lubrication Coatings and Materials

The use of natural (e.g., vegetable-oil based or animal-fat based) biodegradable lubricants. This involves oils that are used for engines, hydraulic applications, and metal cutting applications. In particular, corn, soybean, coconut oils have been used so far (the latter is of particular interest in tropical countries such as India). These lubricants are potentially biodegradable, although in some cases chemical modification or additives for best performance are required. Vegetable oils can have excellent lubricity, far superior than that of mineral oil. In addition, they have a very high viscosity index and high flash fire points. However, natural oils often lack sufficient oxidative stability, which means that the oil will oxidize rather quickly during use, becoming thick and polymerizing to a plastic-like consistency. Chemical modification of vegetable oils and or the use of antioxidants can address this problem 47 .

Production of 3Carotene by Dunaliella

The pigment b-carotene is in high demand as an antioxidant, as a source of provitamin A (retinol) and as a food colouring agent. Its antioxidant activities make it popular for use in health food. D. salina and D. bardawil produce large amounts of -carotene when grown under suitable conditions. The pigment is found concentrated in small globules between the thylakoids of the cell's single chloroplast. The main environmental conditions that stimulate accumulation of the pigment are high light intensities, high salinity and nutrient limitation the slower the cells grow in the presence of high irradiation levels, the more pigment is formed.

Plant Resistance to Toxins 31 Salts

The extent of the adverse effects of salt stress on crops or other naturally growing plants greatly differs and it depends on the type of species or cultivar, growth stage and interaction with other environmental constraints (Ashraf 1994 Ashraf et al. 2008 Munns and Tester 2008). Therefore, a variety of information is available in the literature depicting genetic variation for salt tolerance in crop plants. For example, while appraising the relative salinity tolerance in field pea, canola, dry bean, and durum wheat, Steppuhn et al. (2001) ranked these crops in an ascending order as dry bean field pea durum wheat canola. Of different Brassica species, B. napus was found as the most salt tolerant, while B. campestris and B. nigra the most salt-susceptible (Kumar 1995). Some other studies entailing the exploration of mechanism of salt tolerance in canola have shown that cv. Dunkeld has high salt tolerance due to having higher photosynthetic, antioxidant, ion exclusion and osmotic...

Formation of Reactive Oxygen Species

Because both are highly reactive, carrying out oxidation reactions with many organic molecules at their sites of formation during their short lives. The generation of ROS is a general phenomenon higher plants developed a highly sophisticated antioxidant system during the course of evolution. This consists of several enzymes (superoxide dismutases, catalases, ascorbate oxidases, glutathione peroxidases and glutathione reductases) and antioxidant substrates (ascorbate, glutathione and a-tocopherol). The main sources of ROS under control conditions (an absence of toxic concentrations of heavy metals) are photosynthetic and respiratory electron transport processes. Only when the capacity of cells to suppress the concentrations of ROS is exceeded do these species then damage cells over a long period. Heavy metals play many roles in this respect (Sharma and Agrawal 2005) Inactivation and downregulation of enzymes of the antioxidant defence system Depletion of antioxidant substrates. As long...

Antioxidative Defense Mechanism

Buildup of toxic concentration of heavy metals within the plant tissues results, at some stage of stress exposure, in an increased formation of reactive oxygen species (ROS) (Shah et al. 2001 Verma and Dubey 2003). In general, ROS (O2 , OH, and H2O2) are products of normal cellular metabolism, production of which is under tight control due to cellular antioxidative defense system. Presence of ROS causes oxidative damage to biomolecules such as lipids, proteins, nucleic acids, etc. (Shah et al. 2001 Blokhina et al. 2003). Induction in the activities of antioxidative enzymes and increase in the level of nonenzymic antioxidants are strategies that plants have adopted to scavenge and to reduce oxidative damage caused due to ROS under heavy metal stress (Shah et al. 2001 Fecht-Christoffers et al. 2003 Verma and Dubey 2003).

Forbes Wolfe Nanotech Reports

Given the range of cosmetics using nanoparticulate metal oxides primarily for UV protection it is interesting to note a cosmetics product containing fullerene in the list. In this case the fullerene is claimed to have antioxidant properties. Carbon nanotubes have been used as a reinforcing component in a new baseball bat. Silver nanoparticles feature again, this time in socks where enhanced bonding of the 19 nm silver particles to the polyester fibres is claimed to provide enhanced and longer-lasting antimicrobial and antifungal performance. A novel chewing gum having chocolate flavour, which is apparently difficult to achieve, has been produced using ''nanoscale crystals'' of unknown chemistry to enhance the compatibility of the cocoa butter with the polymers that are used to give the gum elasticity. So-called self-cleaning windows and paint surfaces are also included in the top 10. These are based on photoactive titanium dioxide with the windows gaining a further benefit when it...

Cigarette smoke carcinogens

Tobacco smoke and its condensate contain a complex mixture of over 3800 compounds of these 50 have been identified as being either animal or human carcinogens.9 Of the several carcinogens present in cigarette smoke, polycyclic aromatic hydrocarbons (PAHs) (e.g., benzo a pyrene or B a P) and the tobacco-specific nitrosamines (e.g., or NNK) appear to play a major role in inducing lung cancer.10 Other classes of chemicals such as aza-arenes, aromatic amines (e.g., 4-ami-nobiphenyl or 4-ABP), heterocyclic aromatic amines, aldehydes, miscellaneous organic compounds (e.g., 1,3-butadiene), and inorganic compounds (e.g., Ni, Cr) are also known to be carcinogenic.9,10 In addition, tobacco smoke contains volatile compounds (e.g., benzene) and radioelements (e.g., polo-nium-210) that may also play a role in its carcinogenicity.10 Cigarette smoke also contains free radicals capable of inducing oxidative DNA damage. For example, the tar phase contains stable free radicals, such as catechols,...

Tropospherie Chemistry

Most gases in the troposphere are gradually oxidized by a sequence of reactions involving free radicals. For a given gas, the sequence can be predicted from the principles discussed below, which are also systematized in Figure 5-1. These tropospherie reactions are similar in many ways to those encountered in the stratosphere, which are discussed later in the chapter.

Metabolic activation of cigarette smoke carcinogens and DNA adduct formation

Similarly, several reactive metabolites generated through metabolic activation of PAHs, N-nitrosamines and aromatic amines are capable of forming bulky DNA adducts.15 In addition to the alkylating products induced by NNK, several other carcinogens and free radicals generated in the gas and particulate phases of cigarette smoke are known to hydroxylate DNA bases causing simple base modifications or oxidative DNA lesions, e.g., 8-oxode-oxyguanosine (8-oxodG).17 Some of the aldehydes present in cigarette smoke such as acrolein and crotonaldehyde are known to induce lipid peroxidation generating lipid peroxides capable of forming exocyclic DNA adducts (e.g., etheno adducts, propanodeoxyguanosine adducts) in target tissues of cigarette smokers.18

Validation studies in animals insights into Parkinsons disease and aging

The free radical theory of aging suggests that during the life of an organism, free radicals lead to damage in macromolecules causing a loss of homeostasis and lower enzyme efficiency. This damage ultimately leads to symptoms associated with aging. Since mitochondria are a primary source of reactive oxygen intermediates, then they might play an important role in the aging process. One such idea is that as mitochondria accumulate damage to their macromolecules they become less efficient and generate more reactive oxygen species.17 This ROS generation leads to a vicious cycle of damage and ultimately to a catastrophic demise of mitochondrial function resulting in the death of the cell by apoptosis. We, therefore, wanted to test the idea that mitochondrial DNA will accumulate damage with age. The QPCR assay was able to show that specific regions of the brain of older mice do accumulate both nuclear and mitochondrial DNA damage (Figure 11.4).

Electron Donor Acceptor Interaction Charge Transfer

Senesi and Testini 147,156 and Senesi et al. 150,153 showed by ESR the interaction of HA from different sources with a number of substituted urea herbicides by electron donor-acceptor processes involves organic free radicals which lead to the formation of charge-transfer complexes. The chemical structures and properties of the substituted urea herbicides influence the extent of formation of electron donor-acceptor systems with HA. Substituted ureas are, in fact, expected to act as electron donors from the nitrogen (or oxygen) atoms to electron acceptor sites on quinone or similar units in HA molecules.

Covalent and Enzyme Mediated Binding

- The study on the reaction of several ring-substituted anilines with HS in aqueous solutions showed that the free radical intermediates were converted to stable products by self-coupling or cross-coupling with other radical species (i. e., indigenous humic free radicals becoming incorporated into the HS macromolecule).

Mechanisms of the NaClHM Interaction

It is not surprising that, in the cases where combined crop treatments resulted in a clear suppression of biomass accumulation, some important physiological functions were also disturbed. Thus, in wheat and several barley genotypes, the combined action of these two stressors enhanced the damaging effects of each, additionally reducing the chlorophyll content, suppressing photosynthesis, destroying transpiration, inducing membrane injuries and ionic imbalances, and suppressing the activities of the enzymes involved in nitrogen metabolism, among others (Muehling and Lauchli 2003 Smykalova and Zamecnikova 2003 Huang et al. 2006a,b Kadukova and Kalogerakis 2007). A deeper analysis of the causes of this effect of two stressors showed that a significant interaction exists between Na and Cd in their influence on antioxidant enzyme activity and the accumulation of each element in the plant (Muehling and Lauchli 2003).

Molecular Mechanisms of Metal Homeostasis and Tolerance

Heavy metals such as Cu and Zn (essentials) or Cd (non-essential) can be toxic to plants above a certain threshold. Plants have evolved a regulated network of uptake and distribution enabling an effective protection to the metabolic processes. In general, factors influencing the metal uptake and distribution in plants include (1) mobilization from the soil, (2) uptake and sequestration by metal-complex formation and deposition in vacuoles for detoxification within roots, (3) metal translocation to shoots via xylem, and (4) distribution and sequestration in aboveground organs and tissues (Clemens et al., 2002). A further defensive line against HM effects is a series of antioxidant mechanisms against ROS produced by excess of metal ions. These include enzymes and reducing metabolites (Foyer and Noctor, 2005). synthetase. Glutathione is the precursor of PCs. As a fundamental antioxidant molecule, GSH directly eliminates reactive oxygen radicals induced by HM ions in cells and provides...

Oligosaccharides of Chitin and Chitosan

Their solubility and mode of action depends mostly on their molecular weight, degree of acetylation, degree of polymerization and nature of chemical modification. Oligomers of N-acetylglucosamine (NA-COS) can be used in vitro and in vivo. NA-COS of different molecular weights were extracted from crab chitin and their action against oxidative stress was determined by Ngo et al. (2009). It was concluded that NA-COS with molecular weight of 1-3 kDa was more effective than those of less than 1 kDa in weight. They showed inhibition against DNA and protein oxidation. This studies pave the way for the usage of these NA-COS as a potential antioxidant in the removal of free radicals causing oxidative stress. In addition, they also exhibit the following properties useful in the field of biotechnology Antioxidant activity (Wang et al. 2009)

Analysis and Future Perspectives

The seafood processing waste is an unutilized resource which can be harnessed to recover valuable products which have very important biomedical and biotechno-logical applications. The seafood waste can be used as a cheap medium for the growth of many proteolytic and chitinolytic microbes and at the same time, for the simultaneous recovery of Value Added Products (VAP). There are scanty reports on the utilization of microbes for the production of various VAP from seafood waste which requires a great amount of research in the area of optimization of parameters and production of these VAP. Since biological resurgence is environmentally safer and greener, it should be exploited on a large scale. The VAP can be used in developing countries for nutritional supplementation and other applications. The usage of these VAP as an antioxidant and their role in the inhibition of oxidative stress and tumor requires further research as it would greatly help in the well being of humans. This would be...

Microbial Adaptation to Heavy Metals

The efficiency of phytoremediation technique is, however, influenced by the activity of rhizosphere microbes (Khan et al. 2009) and the speciation and concentration of metals deposited into soil (Wang et al. 1989 Khan 2005a, b). For instance, Lippmann et al. (1995) used PGPR Pseudomonas and Acinetobacter which enhanced phytoremediation abilities (Fe and Zn) of nonhyperaccumulating maize (Zea mays L.) plants by increasing their growth and biomass. Many metals such as Zn, Mn, Ni, and Cu are essential micronutrients. In common nonaccumulator plants, accumulation of these micronutrients does not exceed their metabolic needs (

Extracellular Chelators

Siderophores produced by heavy metal-resistant streptomycetes lowered the formation of free radicals and stimulated plant growth via enhancement of auxin production, as well as by protecting auxins from degradation. Additionally, micro-bial siderophores could be shown to supply plants with iron even in the presence of elevated metal concentrations of aluminum, nickel, copper, manganese and uranium. Besides, it could be shown that cadmium, copper, aluminum and nickel stimulated siderophore production. Thus, a higher efficiency of phytoextraction in siderophore-treated plants was observed (Dimkpa et al. 2008, 2009a, b).

High Mesa Technologies LLC Silent Discharge Plasma Abstract

Los Alamos National Laboratory (LANL) has developed silent discharge plasma (SDP) technology for the ex situ treatment of vapors and hazardous off-gases containing volatile organic compounds (VOCs). In SDP technology, a nonthermal plasma is created by electrical discharges. The plasma breaks down water molecules into hydroxyl and hydrogen free radicals. These radicals are highly reactive and can be used to destroy organic contaminants in vapors.

Plants Response towards Metal Toxicity

Accumulators, on the other hand can concentrate metals in their above the ground tissues to levels far exceeding those present in the soil. Generally the concentrations in the above ground tissues also exceed those in underground tissues 1,12,14 . Resistance mechanisms in the accumulator plants include a high turnover of organic acids such as phytate, citrate and malate and the induction and activation of antioxidant enzymes such as glutathione peroxidase 15 .

Resistance or Tolerance to Metals in Plants

It has been observed that tolerant species possess defense mechanisms linked to cellular antioxidants and to antioxidant enzymes that protect several vital physiological processes against damages promoted by oxygen reactive forms produced by metallic stresses (Panda and Choudhury, 2005). Information has been reported about the hyperactivity of oxidant enzymes and the accumulation of cellular antioxidants in several plants species under Cu and Pb stress (Ali et al., 2003). Several species resistant to Cu had been found in contaminated and uncontaminated areas (Liu et al., 2004). According to De Vos et al. (1992), tolerance to Cu is related to the function of glutathione as an antioxidant substance against free radicals and hydrogen peroxide formed by Cu excess.

Direct Waste Recycling Industry

Advanced direct waste recycling industry could also be included within this category such as converting recycled polypropylene (PP) into the properties of polycarbonate (PC) blends by adding some additives such as fire-retardant, impact modifier, ultraviolet stabilizer and antioxidant.56 This additives will modify the properties of recycled PP into the properties of PC. This new material can replace the PC blends in some applications such as garden spotlights (outdoor lighting) and three-phase circuit breaker boxes. This new material based on recycled PP will maintain a good quality for the product with less cost.

Environmental agents and Parkinsons Disease

Studies with MPP+ support and illustrate the main concepts of this chapter. Chun et al.36 demonstrated that dopaminergic cell death induced by MPP+ was mediated by ROS (specifically H2O2). They also showed that MPP+-mediated apoptosis was inhibited by the antioxidant trolox as well as by a caspase inhibitor. Interestingly, they also showed in the same system that H2O2 caused the same effects as MPP+.36

Brain tumors and environmental agents

In animal models, astrocytomas (glial cell tumors) are induced by chronic treatment with acrylonitrile (ACN) by a nongenotoxic mechanism, and there is strong evidence that ROS and oxidative damage are involved.3940 ACN was chronically administered to rats and oxidative damage was measured in the brain (the target tissue) and the liver (a nontarget tissue). Oxidative damage increased in a dose-dependent manner in the brain but not in the liver.39 Levels of 8-OHdG, malondialdehyde, and trapped hydroxyl free radicals increased in the brain but not in the liver. Catalase activity, which is low in the brain, decreased with increasing dose of ACN in brain but not in the liver in contrast, small changes in superoxide dismutase (SOD) and glutathione peroxidase were noted.39 Cultured rat astrocytes but not hepa-tocytes had increased oxidative damage after exposure to ACN.40 These experiments support the notion that oxidative damage plays a significant role in astrocytoma initiation and...

Nitrones as suppressors of biological oxidative damage

The chemical structures of nitrones are shown in Figure 26.4. Nitrones can be used to spin-trap free radicals in chemical, biochemical and biological systems57-59 and they stabilize highly reactive free radicals so that they can be characterized (Figure 26.4). Because the spin of the original radical is preserved during its reaction with a nitrone, they were termed spin-traps.60 Nitrones began to be used in analytical chemistry for this purpose in 1969,61 and they began to be used in biochemical and biological systems in the 1970s and 1980s. It was not until 1985, when Novelli discovered that PBN was protective in a rat model of traumatic shock62 that the pharmacological potential of these compounds were even considered. PBN has neuroprotec-tive activity during stroke59,63 and PBN and other nitrones have pharmacological potency against a wide range of age-related diseases and pathological conditions. Figure 26.3 This figure shows the chemistry of free radical reactions, the importance...

Nanoparticles as the Drivers of Environment Particle Effects

In this paradigm surfaces, organics and metals can all contribute to inflammation via the production of free radicals. Diesel exhaust particles (DEPs) represent a good exemplar of combustion-derived NPs. Diesel exhaust particles cause inflammation in rat25,26 and human lungs27 following short-term, high-level exposure. Oxidative stress is demonstrable as an increased level of 8 OH dG, the oxidative adduct of hydroxyl radical, in the lungs of rats following exposure and in cells in culture treated with DEP.28,29 The component of DEP responsible for

Phytoremediation Of Waters At An Urban Station Of Water Purification By Water Hyacinth With Preinduction Of

Eichhornia crassipes or water hyacinth is among the plants of HM hyper-accumulators from the aquatic environment. This plant is widely used for tertiary treatment of waste phytoremediation water (Danilin, 2009). Actual prerequisites, however, suggest that the efficiency of HM extraction from wastewater can be improved thanks to preinduction (prestimulation) by protein synthesis of Cd ions - metallothioneins (MT) in the plant root system. Eichhornia crassipes tissues involve MT type 3 (phytochelatins) formed as a result of enzyme reactions with glutathione as well as MT, the synthesis of which is genetically controlled (Seregin, 2001). The feature of heavy metals is the presence of SH-groups which can fix heavy metal ions and inactivate free radicals (Danilin, 2004).

Metabolic Adaptations

Heavy metal uptake is known as a factor inducing oxidative stress in plants (Mittler 2002). In response to ROS production induced by metals, aquatic plants increase the activity of enzymes involved in the scavenging of ROS, as e.g., superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Similarly, metal stress was shown to stimulate the activity of the enzymes involved in biosynthesis and or modification of cellular reducing agents such as ascorbate (AsA) (ascor-bate peroxidase - APX, dehydroascorbate reductase - DHAR, monodehy-droascorbate reductase - MDHAR), glutathione (glutathione peroxidase - GPX, glutathione reductase - GRD), and polyamines (PAs) (polyamine oxidase - PAO, diamine oxidase - DAO). In the aquatic fern Azolla filiculoides, the accumulation of lead in vacuoles has been found to be accompanied with the enhanced activity of tonoplast V-H+-ATPase (Oren-Benaroya et al. 2004). Also, the ability to accumulate proline, being a result of enhanced synthetase...

Toxicology of Nanoparticles

While some particles of general respirable (i.e. not specifically nanoscale) size (e.g. TiO2) are found to be relatively harmless at doses to which humans are exposed, other particle types (e.g. silica and asbestos) have been shown to induce inflammation leading to diseases such as fibrosis and cancer - see, for example, Donaldson et al.25 and Donaldson and Tran.26 In toxicology studies, the ability of such particles to induce toxic effects is related to a number of physico-chemical properties such as size, shape, chemical composition, surface reactivity, surface charge, solubility biodurability.27 For insoluble particles or an insoluble core of a complex particle, only the surface interacts with the biological system.28 Therefore, the total surface area times its reactivity, in contact with the biological system, represents the dose . For a given mass of any particular kind of particle, particle size determines the specific surface area, and so we would expect that particle size is...

Determination of the site of inhibitory action of Wphenylpyrazine2carboxamides in the photosynthetic electron transport

Intact chloroplasts of algae and vascular plants exhibit EPR signals in the region of free radicals (g 2.00), which are stable during several hours (Hoff, 1979) and could be registered at laboratory temperature by conventional continual wave EPR apparatus. These signals were denoted as signal I (g 2.0026, ABpp 0.8 mT) and signal II (g 2.0046, ABpp 2 mT) indicating their connection with photosystem (PS) I and PS II, respectively (Weaver, 1968). Signal II consists from two components, namely signal IIslow which is observable in the dark and signal IIvery fast which occurs at irradiation of chloroplasts by visible light and represents intensity increase of signal II at irradiation of chloroplasts by the visible light. It was found that signal IIslow belongs to the intermediate D and signal IIvery fast belongs to the intermediate ZV Intermediates Z and D are tyrosine radicals which are situated at 161st position in D1 and D2 proteins which are located on the donor side of PS II (Svensson...

Physical And Chemical Properties

Antioxidants Phthalate plasticizers, phenolic antioxidants and phenylene diamine antiozonants nitrosamines from rubber vulcanization Recent years have seen the appearance and evolution of new materials, such as biobased ones, which are produced from renewable sources. Examples are polylactic acid (from corn fermentation) or thermoplastic amides. Recent innovations also include active and intelligent packaging. Active packaging refers to the ability to interact with the internal environment of the packed food via the release or scavenging of substances. These materials are commercialized in some countries such as the United States, Japan and Australia, but not yet in the EU, since the current legislation requires an inertness of the packaging versus the food products. Examples of released substances are antioxidants or antimicrobial agents, whereas scavenging can be directed to oxygen, ethylene, moisture or taint. Intelligent packagings include elements that allow a better traceability...

Plant Mechanisms for the Removal of Dyes

Another detoxifying enzyme that has been studied in plants is glutathione S-transferase. The best known role of this enzyme is in the detoxification of endobiotic and nucleophilic xenobiotic compounds by covalently linking GSH to a broad variety of reactive electrophilic and hydrophobic substrates, which results in the formation of more polar and less reactive conjugates. An increase in the activities of this enzyme has been studied in Phragmites australis in response to Acid Orange 7 (Carias et al, 2008). The plant has shown the potential to degrade the dye with a removal efficiency of 68+8 when used in constructed wetlands. The presence of a dye in the vicinity of a plant can offer stress conditions which the plant will try to overcome with inherent stress response mechanisms. Plants react to stress conditions by increasing the concentration of reactive oxygen species using enzymes like NADPH oxidase in order to signal plant defences. This in turn leads to the activation of...

Effects of Heavy Metals on Fungal Physiology

Metals exert toxic effects in many ways they can (1) inhibit enzymes by the interactions with proteins (2) displace or substitute for essential metal ions (3) cause disruption of membranes, and (4) cause oxidative stress or interact with systems that normally protect against the harmful effects of free radicals.

Sulfur And The Sulfur Cycle

Sulfur Cycle

Sulfur is an important, relatively abundant, essential element. As is true of many elements, it takes part in a biogeochemical cycle discussed shortly. It is a major component of air pollution, particularly in industrialized areas, although natural sources of sulfur also contribute. Several oxidation states are encountered in environmental systems the most stable under aerobic conditions is S(VI) as in SO3 and sulfates. The reduced form S(-II) is encountered in organic sulfides, including some amino acids, in H2S, and in metallic sulfides. It is a reduction product of sulfates under anaerobic conditions. Oxidation of sulfides produces chiefly SO2 S(IV) as the immediate product. Sulfur dioxide and sulfites, the salts produced when SO2 reacts with base, are reducing agents and are used as antioxidants in some foods (e.g., cut fresh fruits and vegetables, some shellfish, wine). While sulfite is generally not considered harmful, it causes asthmatic reactions, sometimes severe, in...

Toxins and Their Types

The salt effects on plant growth and development have been discussed in detail in a number of reviews. Their main focus has been on physiology of salt toxic-ity and tolerance, intra- and inter-cellular ion transport as well as long distance transport in plants, identification and characterization of traits and or genes responsible for ion homeostasis, osmotic adjustment, and antioxidants whose expression is regulated by salt stress (Ashraf 1994, 2004 Ingram and Bartels 1996 Tester and Davenport 2003 Flowers 2004 Munns 2005 Munns et al. 2006 Munns and Tester 2008). Of various plant responses to salt stress, accumulation of compatible solutes (organic compounds of low molecular weight) is one of the prominent responses of plants to salt stress, because this phenomenon helps the plant to become acclimated to different stressful environments (Bohnert and Jensen 1996 Ashraf and Harris 2004 Ashraf and Foolad 2007). Various compatible osmolytes such as proline and glycinebetaine are...

Roots Plant Enginee Rganapathy

Al-Rawahy SH (2000) Study of the adaptive mechanisms evolved through selecting NaCl tolerant cells and plants of alfalfa (M. media cv. Rambler). Ph.D. Thesis. University of Wales, Swansea Arfan M (2009) Exogenous application of salicylic acid through rooting medium modulates ion accumulation and antioxidant activity in spring wheat under salt stress. Int J Agric Biol 11 437-442 cells to water stress. Plant Physiol 82 890-903 Rodriguez-Rosales MP, Kerkeb L, Bueno P, Donaire JP (1999) Changes induced by NaCl in lipid content and composition, lipoxygenase, plasma membrane H+-ATPase and antioxidant enzyme activities of tomato (Lycopersicon esculentum Mill) calli. Plant Sci 145 83-91 Romero JM, Maranon T (1994) Long term responses of Melilotus segetalis to salinity. I. Growth

Steinkopff Prize 1993 recipient Duan Vudelic

Been shown that the almost established hypothesis of the origins of the high catalytic activity within amorphous phases of oil shales and kerogens is not universally valid. In reality, two systems exist, with high and low catalytical activity, and free radicals playing the main role in the latter. In the early 1980s, Prof. Vucelic became interested in biophysics. Interphases provided the bridge to this field because, starting from the membrane, the whole cell may be regarded as an interphase. This approach rapidly led to some outstanding results. First, a combined bio-thermo-tropic effect was demonstrated for folic and fatty acids. Second, the well known physiological phenomenon that long chain fatty acids adsorb through the wall of the digestive tract, in contrast to the short chain ones which pass directly through the venal port, was explained on the basis of thermodynamics, e.g., only long chain fatty acids form micelles. Finally, the expectation of perturbation of water transport...

Examples Of Using Enzymes For Bioremediation

Wu et al. (194) and Nicell et al. (202) performed investigations to optimize the reaction conditions and to develop the most suitable reactor configuration for peroxidase-mediated removal of phenols from wastewaters. Optimal conditions for pH, molar ratio of hydrogen peroxide to phenol, HRP and additive concentrations, as well as reaction times were determined to achieve at least 95 removal of phenols from synthetic wastewater (194). The enzyme-catalyzed process was implemented in a continuously stirred tank reactor (CSTR) configuration (202). In such a configuration the inactivation of the enzyme through free radicals (see previous section) was reduced by lowering the reactant and enzyme concentrations immediately upon entering the reactor. Single- and multiple-CSTR performances were proved to be superior to batch reactor performance (202). In further studies, the feasibility of the enzyme process to treat a foundry wastewater was evaluated (193). The treated sample was a composite...

Sustainable Energy Development

Bienaventuranzas Explicacion

Proposing wrong solutions for various problems has become progressively worse. For instance, the US is the biggest consumer of milk, most of which is fortified with calcium. Yet the US ranks at the top of the list of osteoporosis patients per capita in the world. There are similar standings regarding the use of vitamins, antioxidants, sugar-free diet etc. Potato farms on Prince Edward Island in eastern Canada are considered a hot bed for cancer (The Epoch Times 2006). Chlorothalonil, a fungicide, which is widely used in the potato fields, is considered a carcinogen. The United States EPA has classified chlorothalonil as a known carcinogen that can cause a variety of ill effects, including skin and eye irritation, reproductive disorders, kidney damage, and cancer. Environment Canada (2006) published lists of chemicals that were banned at different times. This indicates that all the toxic chemicals used today are not beneficial and will be banned from use some day. This trend continues...

Mechanism of Salt Tolerance in Glycophytes and Halophytes

Have a capacity for osmotic adjustment in that these plants accumulate osmolytes such as glycine betaine and proline that maintain the osmotic balance disrupted by the presence of ions in the vacuole (Wang et al. 2004). Halophytes can maintain high metabolic activity even at inhibitory concentrations of intracellular Na+ and possess enhanced antioxidant mechanism (Fang et al. 2005). On the other hand, Jithesh et al. (2006) concluded that the antioxidant enzymes protected halophytes from deleterious ROS production during salt stress. It is clear that salinity induces oxidative stress in plants. Therefore, increases in malondialdelyde and lipid peroxidation are generally used as indicators for ROS production during or after salt stress conditions. Works with halophytes suggested that maintenance of malondialdehyde levels after salt stress and the induction of antioxidant enzymes confirmed the role of antioxidants in salt tolerance trait in halophytes (Parida et al. 2004 Fang et al....

Polymetallic Contamination

In aquatic plants, one of the most comprehensive investigations of a two-metal effect is the protection of Ceratophyllum demersum (Coontail) by zinc ions during acute cadmium stress, as described in a set of papers by Aravind, Prasad, and coworkers. Part of it is summarized in a review paper of Aravind and Prasad (2005a). They show the ability of Zn2+ to alleviate the toxic effect of Cd2+ on the chloroplast membrane structure, pigment biosynthesis, activity of photosystems, photosynthetic electron transport and net photosynthesis rate (Aravind and Prasad 2004), energy transfer in photosystem II (Malec et al. 2008), as well as on the carbonic anhydrase conformation (Aravind and Prasad 2005b). Plants treated with both Cd and Zn ions showed significantly lower Cd and higher Zn uptake than those treated with the same Cd concentration only. Cd-induced oxidative stress symptoms, such as lipid peroxidation, lipoxygenase activity, and electrical conductivity, were efficiently reduced by Zn...

Phytoremediation Strategies for Overcoming Salinity Problems and Use of Halophytes as Companion Plants

Metabolized in the cell and how these traits would be improved through biochemical or genetical ways. It is also important to determine the level of salt tolerance and antioxidant capacity of these plants, By this way, suitable companion plants would be selected to improve the saline areas. For example, Dikilitas et al. (2007) reported the possible use of Peganum harmala as companion plants by determining the antioxidant capacity and ion absorption rate at various NaCl concentrations. They concluded that the halophyte P. harmala was more tolerant to salt than that of the glycophytes.

Impact of Mussel Consumption to Human Health 9441 Beneficial Effects If Mussel Consumption

By 2002, fish fisheries and aquaculture products contributed 12 to the total protein for human consumption, although there are no detailed global statistics on the provision of other essential minerals and components, FAO (2006). The total content of minerals in raw marine fish and invertebrates is in the range of 0.6-1.5 wet weight, Ozden et al. (2010). An epidemiological study in Japan showed that seafood was the largest source of vitamin B6 (16-23 of the total intake) and B12 (77-84 ) in the diet, Yoshino et al. (2005) . Many species of fish and shellfish are rich sources of Omega 3 fatty acids, Ackman et al. (2000) and the health benefits associated with the consumption of seafood products are particularly important for the prevention of heart-related diseases and for many vulnerable groups, such as infants and children, and pregnant and lactating women, Cozzolino et al. (2001), Christophoridis et al. (2009) and the positive impact of seafood consumption on bone mineral density...

Mechanism of Free Radical Scavenging and Role of Phytohormones in Plants Under Abiotic Stresses

Abstract Environmental stresses result in the generation of reactive oxygen species (ROS) in plants. ROS accumulate in cells and lead to the oxidation of proteins, chlorophyll, lipids, nucleic acids, carbohydrates etc. Cells have evolved intricate defense systems including enzymatic (superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductases (GR), monodehydroascorbate reductases (MSHAR), dehydroascorbate reductases (DHAR), glutathione peroxidase (GPX), guaicol peroxidase (GOPX) and glutathione-S- transferase (GST) and non-enzymatic systems such as ascorbic acid (ASH), glutathione (GSH), phenolic compounds, alkaloids, non-protein amino acids and a-tocopherol, which can scavenge the indigenously generated ROS. Plant stress tolerance mediated by antioxidants has been shown by many workers. Antioxidant resistance mechanisms may provide a strategy to enhance plant stress tolerance. Various enzymes involved in ROS-scavenging have been manipulated,...

Treatment of Polluted Soils

Is considered an alternative method for the detoxification of contaminated aquatic and terrestrial environments (Sjoblad and Bollag 1981 Duran and Esposito 2000 Chiacchierini et al. 2004 Wesenberg et al. 2003 Claus and Filip 1991 Filip and Claus 1995 Nannipieri and Bollag 1991 Bollag 1992 Ahn et al. 2002 Gianfreda and Rao 2004 Gianfreda et al. 1999 Bollag et al. 2003). Numerous studies have shown that white-rot fungi and their ligninolytic enzymes are capable of the in vitro transformation or degradation of several xenobiotics. The underlying mechanism for laccase-induced detoxification involves oxidation of the pollutants to free radicals or quinones that subsequently undergo polymerization and partial precipitation. The pollutants are less toxic in their insoluble form and can be removed from waters by physical procedures (Bollag et al. 1988 Claus and Filip 1991 Dec and Bollag 1990 Nannipieri and Bollag 1991). In soils, detoxification occurs through the covalent coupling of the...

Effect of Metals on Photosynthesis in Aquatic Macrophytes

Biphosphatecarboxylase-oxygenase (Rubisco) Transthylakoidal pH gradient Activities of antioxidant enzymes C02 assimilation and photosynthetic pigments Cu uptake Salvinia possess efficient antioxidant Dhir et al. do not show the symptoms of toxic damage. For example, Salvinia sp., a fast growing free-floating aquatic plant, known for its high productivity of biomass, has been shown to accumulate different heavy metals, namely, Cr, Cu, Cd, As, and Pb, and the extent of metal uptake was higher for its higher concentration in water (Nichols et al. 2000 Al-Hamdani and Blair 2004 Hoffmann et al. 2004 Dhir et al. 2009). In the course of the accumulation, the decrease in the content of photosyn-thetic pigments, both chlorophylls and carotenoids, a lowered CO2 assimilation, and an inhibition of plant growth were observed (e.g., Nichols et al. 2000 Al-Hamdani and Blair 2004). However, Dhir et al. (2009) showed an increase in the photosynthetic activity of PS I and PS II as well as...

Repair of DNA damage

To counter the impact of this extensive damage to the DNA that is constantly occurring in each cell, organisms have developed several, generally nonredundant, pathways for repairing different DNA lesions. Nucleotide excision repair (NER) removes photoproducts induced in DNA by exposure to UV radiation and also the bulky DNA adducts formed following exposure to a multitude of chemicals.28-32 The NER pathway involves more than 30 proteins, at least 13 of which form a single multiprotein complex. Two DSB repair pathways repair damage produced directly by exposure to ionizing radiation or indirectly by incomplete repair of single strand damage.33,34 Homologous recombination repair (HR) relies on extensive nucleotide sequence complementarity between the intact homologous partner chromosome or sister chromatid and the damaged structure for strand exchange.35 Non-homologous end joining repair (NHEJ) requires little or no sequence homology and is mediated by direct end-joining.36 The more...

Lubricants 1431 Introduction

Vegetable oils can be considered environmentally friendly because these materials are non-toxic, renewable resources and lower cost alternatives to synthetic fluids. They have low volatility, excellent lubricity, favorable viscosity temperature characteristics and higher solubilizing capacity for contaminants and additives than mineral base oils 70 . The ester linkages deliver inherent lubricity and enable the oils to adhere to metal surfaces. In all of these technical properties, the vegetable oils are comparable or better than mineral oils 69 . Vegetable oils have demonstrated to be potential as use for biodegradable lubricants in applications that include engine oils, hydraulic fluids, and transmission oils 72-76 . Biodegradability provides an indication of the persistence of any particular substance in the environment and is the yardstick for assessing the eco friendliness of substances 77 . However, extensive vegetable oils use is restricted due to their poor fluid flow behavior,...

Classification of C02

chemicals are chemicals approach initiated by Linus Pauling's vitamin C and antioxidant experiments. This approach advanced the principle that, whether from a natural or synthetic source and irrespective of the pathway it travels, all vitamin C is same. This approach essentially disconnects a chemical product from its historical pathway. Even though the role of pathways has been understood by many civilizations for centuries, systematic studies questioning the principle have only been a recent development. For instance, only recently Gale et al. (1995) reported that vitamin C supplements did not lower death rates among elderly people and may actually have increased the risks of dying. Moreover, 6 carotene supplementation may do more harm than good for patients with lung cancer (Josefson 2003). Obviously, such a conclusion cannot be made if subjects were taking vitamin C from natural sources. In fact, the practices of people who live the longest lives indicate that natural products do...

Ascorbic Acid Vitamin C

Among the non-enzymatic antioxidants AsA is the most extensively studied molecule and is found in various plant cell types (Horemans et al. 2000 Smirnoff 2000). Although the precursor of L-ascorbic acid is D-glucose, its biosynthetic pathway is still unclear (Foyer and Noctor 2005). Normally, ascorbate occurs in the reduced form (AsA). (90 of the ascorbate pool) and its intracellular concentration ranges from 20 mM in the cytosol to 300 mM in the chloroplast (Noctor and Foyer 1998). The synthesis of ascorbate takes place in mitochondria and is transported to other cell components through a proton-electrochemical gradient or through facilitated diffusion (Horemans et al. 2000). AsA has effects on different physiological processes including growth regulation, differentiation and metabolism of plants. The basic role of AsA is to protect plants from the deleterious effects of H2O2 and other toxic derivatives of oxygen. AsA acts essentially as a reductant and it scavenges many types of...

Jana Kadukova1 and Jana Kavulicova2

Phytoremediation advantages are widely known nowadays. It is a method applicable for large areas with low concentration of pollutants treatment or areas where only the finishing step of cleaning is required. Very often these kinds of places represent great problems because there is no possibility to take all the soil to the landfills, and often they are part of agricultural fields. There are many studies dealing with application of a variety of plants for the treatment of soils contaminated by heavy metals or organics. Plants growing on these contaminated soils developed several ways of coping with the toxicity of pollutants including avoiding their accumulation, different detoxification mechanisms or even metal excretion from their body. Our work is focused on heavy metal contamination cleanup by phytoremediation with the aim to describe some of the possible ways to assess the stress of plants. There are several factors which can be used in the plant stress assessment such as...

The sulphur cycle and atmospheric acidity

If CO2 were the only atmospheric gas controlling the acidity of rain, then the pH of rainwater would be close to 5.6 (see Box 3.7). However, most pH measurements of rainwater fall below this value, indicating other sources of acidity. Much of this 'extra' acidity arises from the sulphur cycle, as shown in Fig. 7.18. Only two major routes give rise to the sulphur acidity. One is the burning of fossil fuels to produce the acidic gas SO2. The other is the production of the gas DMS by marine organisms, which then degases to the atmosphere across the air-sea interface (Fig. 7.23). Once in the atmosphere the DMS is oxidized by powerful oxidants, called free radicals (see Section 3.5). The two free radicals important for oxidation of DMS are hydroxyl (OH) and nitrate (NO3). The products of this oxidation are several, but the two most important are SO2 and methane sulphonic acid (MSA or CH3SO3H). The SO2 formed in this way is chemically indistinguishable from that coming from the burning of...

Solid phase extraction

The QuEChERS technique has proven successful for the determination of pesticides in a variety of fruit and vegetables, e.g., 64-66 and also recently in fatty matrices such as olive oil 67 , and milk and eggs 68 . The technique was also used to analyse acrylamide in various food matrices 69 and ivermectin in salmon and antioxidants in pet food 70 .

Background Organic Chemistry

The organic compounds of interest environmentally are mostly electrically neutral molecules containing covalent bonds. Stable compounds of this type inevitably involve the formation of four bonds by carbon in carbon-centered free radicals, they form three bonds. Conceptually at least, chemists view all organic chemicals as derived from those simple organic compounds that contain only carbon and hydrogen, i.e., hydrocarbons. We shall follow this convention and divide our discussion into several sections, most of which deal with specific types of hydrocarbons.

Arsenic carcinogenesis

Arsenic is present in various forms in the environment. It is closely linked to several human diseases including blackfoot, diabetes, hypertension and cancers of the skin, lung, bladder and liver. Much research has shown that metabolism of arsenic increases the level of ROS.52 Wang et al.52 demonstrated that arsenite enhances production of ROS and causes ROS-mediated apoptosis in Chinese hamster ovary cells and that antioxidants could prevent the ROS-mediated effects. N-acetyl-cysteine was quite effective, whereas Trolox and Tempo (2,2,6,6-tetramethyl-1-piperidinyloxy) were less effective. Tempo is a stable nitroxide compound.

Biomarkers of genetic integrity or damage

Efforts are also being made to develop biochemical markers of sperm DNA damage. Reactive oxygen species (ROS) are a group of potentially destructive molecules implicated in the oxidative damage of biological structures. These ROS, including the superoxide anion, the hydroxyl radical, and hydrogen peroxide, may either be produced endogenously through cellular pathways of the mitochondria and lysosome or induced exogenously in reaction to environmental assaults. Ultraviolet and x-ray radiation and oxi-datively reactive compounds, such as those found in cigarette smoke, alcohol, and air pollution, have all been shown to induce the formation of harmful ROS.125 Over the past decade, concern has been raised after numerous studies reported the reactivity of ROS to DNA nucleotides and suggested the potential for ROS to generate genetic mutations that may evolve to cancer or birth defects if germ cells are damaged.126127 8-hydroxydeoxyguanosine (8-OHdG) is one of many products of oxidative DNA...

Fungal Decolorization and Degradation of Synthetic Dyes

Manganese Peroxidase

Despite all efforts, the mechanism of fungal-mediated dye decolorization and the role of ligninolytic enzymes in the process under in vivo conditions are still disputed. Mechanisms, such as sorption to the fungal biomass, the participation of free radicals, and lipid peroxides can also be involved in dye degradation by ligninolytic fungi. This chapter describes the key achievements in the study of synthetic dye degradation by white rot fungi and mechanisms involved.

Pharmaceutical And Edc Removal During Wastewater Treatment

Advanced Oxidation Process (AOPs). These processes utilize highly reactive chemical species such as free radicals to oxidize chemical contaminants in water (Singer and Reckhow 1999). The most common AOPs, such as UV peroxide and ozone peroxide, involve hydroxyl radical ('OH)-dominated reactions (Snyder et al. 2006,2007). Other AOP technologies, such as UV titanium dioxide photocata-lysis and nonthermal plasma (NTP), may be viable alternatives in the future (Benotti et al. 2009b Gerrity et al. 2009). Although AOPs provide some level of treatment with their base mechanisms (e.g., direct photolysis of chemical contaminants from UV peroxide), the dominant treatment pathway generally involves oxidation by highly reactive, nonspecific OH.

How Is Energy Conserved With Sunflower

Sunflower oil often referred to as sunflowerseed oil or sunoil is obtained from the seed of the plant helianthus annus, which is native to North America. Sunflower oil is currently the fourth largest edible oil commodity traded on the world market following palm oil, soybean oil and coconut oil 25 . Recently, high oleic acid crops have been developed whose oil has higher oxidative stability than the standard genotypes 26 . The major sunflower growing regions in the world include Russia, Ukraine, France, Romania, Hungary, Bulgaria, Spain, Italy and others. The Asian sunflower growing regions include China, India and Pakistan 27 . Sunflower oil contains the highest level of alpha tocopherols, the most active form of vitamin E, which will act as an antioxidant during storage to overcome the auto oxidation of fatty acids 28 . Fatty acid composition of common sunflower oil, high oleic sunflower oil and high oleic and high palmitoleic sunflower oil 29 are given in Table 11.4.

Phenols

Phenol and substituted phenol compounds (Fig. 19) are known to be widespread as components of industrial wastes. These compounds are made worldwide in the course of many industrial processes, as for example in the manufacture of plastics, dyes, drugs, and antioxidants, and in the pulp and paper industry. Organophosphorus and chlorinated phenoxyacids also yield chlorinated and nitrophenols as major degradation products. 4-Nitrophenol was reported as a breakdown product after the hydrolysis and photolysis of Parathion in water and chlorinated phenols are formed by the hydrolysis and photolysis of chlorinated phenoxyacid herbicides 251-253 .

Heavy Metal Toxicity

Majority of heavy metals have strong affinity toward SH group of enzymes and usually inhibit their activities during this interaction by blocking the SH group or masking the active site of enzyme. There are about hundred known enzymes, whose activity is affected by SH group interaction with heavy metal ions (Seregin and Ivanov 2001). Table 2.1 presents effects of two common heavy metals, Cd and Pb on certain enzyme activities. The resistance of one and the same enzyme to heavy metals varies with plant species. The decline in enzymatic activity by exposure of heavy metals is crucial for understanding the multidirectional effects of these metals on diverse aspects of cell metabolism. In some cases these ions even promote enzyme activity. The direct stimulation of catalase, peroxidase and superoxide dismutase has not been proved unambiguously because these activities decrease following short exposure to heavy metal ions. Apparently it is the oxidative stress that enhanced the activities...

Plasma Membrane

Thus, tolerance may involve the protection of plasma membrane integrity against heavy metal damage that would produce increased leakage of solutes from cells (De Vos et al. 1991 Strange and Macnair 1991 Meharg 1993). However, there is little evidence to show how this might be achieved. For example, metal-tolerant plants do not appear to possess enhanced tolerance to free radicals or reactive oxygen species, but rather rely on improved mechanisms for metal homeo-stasis (Dietz et al. 1999). Again these effects on membranes are metal-specific since, in contrast to Cu, Zn protects membranes against oxidation and generally does not cause membrane leakage (Ernst et al. 1992 Cakmak 2000). Another factor that may be involved in the maintenance of plasma membrane integrity in the presence of heavy metals could be enhanced membrane repair after damage (Salt et al. 1998). This could involve heat shock proteins or metallothioneins, and evidence for this is discussed in the following sections.

General Principles

Polymers that cure by free-radical mechanisms are the basic raw materials for radiation curing. Classical curing of these polymers has been accomplished by heat or by absorption of sunlight. Both processes dissociate the contained free-radical source into active free radicals, which initiate polymerization of the curable polymer. The speed at which free radicals are formed and their concentration, determine the properties of the cured polymeric material. Both classical approaches to free-radical source dissociation require rather lengthy periods of time in addition, the thermal heating is energy inefficient. Use of ultraviolet, electron beam or infrared energy, however, can greatly speed the formation of free radicals from the source.

Bonding

Humus is also capable of forming covalent bonds with aqueous solutes 40 . Humus is the site of considerable microbial activity where living and dead organisms and extracellular enzymes are typically associated with it as part of the material 25, 30 . The presence of enzymes can catalyze reactions. It is also reported that humus contains stable free radicals, which make it very reactive and able to form covalent bonds or create ions. It is reasonable to assume that charge-transfer reactions between free radicals are important in the aggregation of humic materials in light of the high concentrations of free radicals which have been detected in both soils and aqueous humic acid preparations. The free radicals detected in soils and humic acids may arise from the reduction of a dia-magnetic molecule by a solvated electron, enzymatic reactions, or photolysis 26,27,29,41 .

Pigments

Shell fish waste is one of the important sources of carotenoid pigments (Shahidi et al. 1998) . These lipid soluble pigments produce yellow-red color in plants and animal products. This class of pigments include carotene, Asthaxanthin, its esters, zeaxanthin, lutein, etc. (Khanafari et al. 2007). Amongst them, Asthaxanthin is the most important. It is a ketocarotenoid (3, 3'-dihydroxy-b, b-carotene-4, 4'-dione). It has a similar structure to b-carotene but is a more potent antioxidant than b-carotene. It is highly polar but non-toxic. It is the oxidized form of b-carotene responsible for the pink reddish pigmentation in crustaceans and salmons (Stepnowski et al. 2004). Astaxanthin is a xanthophyll which has inherent properties like antioxidant and anti-carcinogenic, as well as Vitamin A precursor (Stepnowski et al. 2004). Due to its outstanding antioxidant activity, astaxanthin has been attributed with extraordinary potential for protecting organisms against a wide range of ailments...

Lipids

Seafood waste has considerable amounts of lipids which can be used for the extraction of retinol, Cholesterol and a-tocopherol. The removal of lipids was up to 76.9 by using lactic acid fermentation compared to the removal of lipids by chemical treatment (46.1 ) as reported by L'opez-Cervantes et al. (2006). Similarly the removal of calcium was higher by using bioconversion (Beaney et al. 2005). Retinol, a-tocopherol and cholesterol are amongst the nutritionally important lipids in foods Retinol is also known as Vitamin A. It is an important micronutrient required for vision, growth, reproduction, and maintenance of the immune system (Ball 2000 De Vries and Silvera 2002). a-Tocopherol (Vitamin E) is an important antioxidant and is required for muscular and reproductive functions (Lopez-Cervantes et al. 2006). Cholesterol is another important lipid which is a precursor of bile acids, steroid hormones, and Vitamin D (Lopez-Cervantes et al. 2006).

Amino Acids

Protein hydrolysates from shrimps exhibited antioxidant activity (He et al. 2006). From studies carried out by Katayama and Mine (2007), it was shown that amino acids exhibited protection of hydrogen peroxide induced tissue oxidative stress in human epithelial cells. Fermented shrimp waste contains a large amount of essential amino acids (Lopez-Cervantes et al. 2006) . Protein hydrolysates produced by the enzymatic processing inhibited the Angiotensin-I-converting enzyme as studied by Cheung and Li-Chan (2010). They also concluded that every 1,000 g of wet shrimp waste, approximately 30 g of peptide amino acid materials were recovered in the soluble hydrolysates, representing 12 of the solid matter in the shrimp waste.

Food Spoilage

When fresh foods are allowed to stand at room temperature, they begin to deteriorate. The changes in the composition of the food are brought about by the action of enzymes and microorganisms, including molds and yeasts. Factors such as oxygen, sunlight, warmth, dehydration, insects, and other vermin accelerate decomposition, contributing to the unpleasant appearance and taste of the food, the loss of freshness, and changes in the color and odor. Food that has been permitted to decompose loses much of its nutritive value. Atmospheric oxidation causes a reduction of the vitamin content and quality, a breakdown of the fats, then the proteins, to form hydrogen sulfide, ammonia, and other products of decay. Antioxidants are sometimes used to slow down food deterioration, rancidity, or discoloration due to oxidation. These include ascorbic acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), citric acid, and phosphates. The Food and Drug Administration (FDA) requires that...

Conclusions

The chemical and structural nature of humic substances coating solid phase surfaces makes them active in the environmental fate and transport of organic pollutants. The presence of bound enzymes and free radicals in the material allows it to form covalent bonds with a variety of molecules. The existence of nonpolar regions of the humic matter introduces the possibility of intramolecular sorptive partitioning of nonpolar organic compounds into the humic matrix. The extent and polarizability of the humic matter surface enable it to bind to materials by van der Waals forces. The existence of electrostatic charges on the surface of the substance makes it reactive with respect to water, ions, and mineral surfaces. The nature of the surface chemistry grants humic matter a surface charge which is pH-dependent. Hence, the tendency to flocculate or disperse is more or less a function of pH and ionic character of the solution.

Acoustic Energy

The use ofultrasound (sonochemistry), for example, acoustic energy effects, has a long tradition, similar to photochemistry. Although commercially applied in several applications, mainly in cleaning and decontamination or in the textile industry (dye dispersion and fixation), its use to improve performances in chemical reactions has essentially remained on a laboratory scale. The main focus of research has been on liquid-phase systems, where exposure to ultrasound results in formation, growth and subsequent collapse of microbubbles (microcavities), occurring over an extremely short period of time (milliseconds). The microimplosions are accompanied by an energy release with very high energy densities (of up to 1018kWm 3), which leads to local generation of extremely high temperatures and pressures, up to about 5000 K and about 50 000 bar, respectively, as well as release of free radicals due to pyrolysis of water 145-148 . of energy over a very small location, resulting in very high...

Nadph

The four important enzymatic components of the cellular antioxidant defense system. Superoxide dismutase (SOD) catalyzes the dismutation of superoxide (O2-O to peroxide. Catalase reduces peroxide to H2O. GSH peroxidase also detoxifies peroxide by reducing it to H2O. GSH reductase re-reduces the oxidized glutathione (GSSG) to GSH. The NADPH required for the reduction of GSSG to GSH is primarily supplied by the oxidation of glucose via the pentose phosphate pathway. (Based on Mottet, N.K., Ed. Environmental Pathology. Oxford University Press, New York, 1985.)

Applications

A search for new tyrosinase inhibitors has also been launched by the cosmetic and pharmaceutical industries. Although melanin plays a crucial protective role against UV radiation and as an antioxidant, abnormal melanin pigmentation is a serious aesthetic problem in humans. Thus, tyrosinase inhibitors are important in the cosmetic industry due to their skin whitening and preventive effects (Parvez et al. 2007). The substrate stereospecificity of the monophenolhydroxylase and diphenoloxi-dase activities of tyrosinase are the basis for many industrial applications (Halaouli et al. 2006) as biosensors for the monitoring of phenols in the pharmaceutical industry for the production of o-diphenols (e.g., L-dopa, dopamine for the treatment of Parkinson's disease), and for the synthesis of biopolymers. Synthetic melanins find application as protective agents against radiation (UV, X-rays, g-rays), cation exchangers, drug carriers, antioxidants, antiviral agents, and immunogens (Nosanchuk and...

Selenium

In spite of the toxicity of selenium, it is an essential trace element for a number of organisms, including humans. It is used in the glutathione peroxid-ase enzyme system to prevent the formation of peroxides and free radicals from the oxidation of unsaturated fats. Recently, evidence has been presented suggesting that selenium is effective in preventing the onset of cancer that is, the incidence of cancer can be correlated inversely with selenium levels in the blood. Interestingly, this effect is counteracted by high levels of zinc. If the foregoing observation is valid, it illustrates the difficulty in dealing with trace elements. Eliminating selenium too thoroughly from food and water supplies may do harm, just as too high an intake certainly will.

F UV carcinogenesis

The role played by free radicals in carcinogenesis has been debated for many years. There is little doubt that carcinogenesis involves free radical events and changing these events can effect the rate if not the final outcome of carcinogenesis. However, it is not clear how or at what stage antioxidants or other agents that affect free radical processes interfere with carcinogenesis. This discussion will focus on the early phases of carcinogenesis. Skin tumors are a good example because they are largely due to UV radiation and the ROS-mediated processes caused by UV.42 UV-mediated tumor formation in rodents was studied by Black and colleagues in the 1970s under the basic premise that ROS are important mechanistically.43-46 They determined that a cholesterol epoxide formed by ROS intermediates was important in the carcinogenic process.43 They showed that UV-mediated tumor formation decreased significantly in animals fed a diet containing antioxidants (i.e., 1.2 ascorbate, 0.5 butylated...

[3 2 Cycloaddition

Imidazolines exhibit a wide range of pharmacological activities such as anti-hyperglycemic, antioxidant, anti-cancer, antitumor, etc.63a,b and thus synthesis of these compounds is of considerable interest. 3 + 2 Cycloaddition of azir-idines with nitrile has been reported in neat in the presence of Sc(OTf)3 to produce substituted imidazolines (Scheme 5.43) in high yields.63c

Fullerenes

Buckminster fullerene or C60 is a compact, cage-like molecule comprising 60 carbon atoms. C60 can be viewed as a nanoparticle and has received some toxicological attention. The basic graphene structure of fullerene can be func-tionalised in various ways to change the physical properties of the fullerene, for instance making it more dispersible soluble.103 Carboxylated fullerenes are slightly less toxic than the native C60 and hydroxylated fullerenes are virtually non-toxic to human dermal fibroblasts.103 The toxicity of the native C60 appeared to be due to the ability to generate superoxide anions.103 Isakovic et al. showed a similar effect with the native C60 being 30 times more toxic on a mass basis than a soluble hydroxylated C60 in a range of human tumour cell lines. The authors concluded through the use of antioxidants, and by identifying different types of cell death with the two fullerenes, that unmodified C60 had strong pro-oxidant capacity responsible for the rapid necrotic...

Abrasive Wear

Because of difficulty, expense, and safety issues, wind turbine operators strive to minimize the frequency of gear oil changes. The enemy is oil degradation, which includes loss of additives, excessive accumulations of fine particles, and especially oil oxidation. This well-documented oxidation mechanism starts when oxygen atoms are incorporated into oil molecules producing chemically reactive free radicals, which in turn initiate chain reactions involving thousands of oil molecules and producing acids and polymeric compounds. The acids promote corrosion. The polymers are gummy substances that (1) thicken the oil, fostering filter bypassing and lubricant starvation during cold starts, (2) foul passages and flow controls, another source of lubricant starvation, and (3) coat and thermally insulate heat exchange surfaces, fostering excessive heat build-up and elevated temperatures during operation. Antioxidants (free-radical scavengers) are incorporated into gear oil additive packages to...

Food Irradiation

At high dose levels, radiation-chemical (radiolytic) changes in food not only can have an adverse effect on color and flavor (e.g., changing the flavor of dairy products and introducing rancidity in food with high fat content) but also can cause partial loss of vitamins. These deleterious effects can be reduced by vacuum-packing the food to remove oxygen and freezing it before irradiation, a practice that reduces the formation of substances by reaction of the radiolysis products of water (Section 13.8) with the chemical constituents of food. Radiolysis of the complex molecules in food also produces free radicals that can react to form a wide variety of molecules known to be mutagenic or carcinogenic. These are the same compounds that are introduced when food is processed without ionizing radiation (e.g., by cooking) and are, therefore, normally present in processed food.

Chlorinated Benzenes

Although benzene does not readily undergo addition reactions with molecules or ions that are not free radicals, it does participate in substitution reactions One of its hydrogen atoms can be replaced by a group such as methyl, hydroxyl, etc., that forms a single bond. Of particular interest is substitution by chlorine, since many compounds of environmental concern contain chlorine-substituted benzene rings. When benzene is reacted with chlorine gas in the presence of a catalyst such as iron(III) chloride, FeCl5, one of the hydrogens (explicitly drawn on the ring below for clarity) is replaced by chlorine, and HCl gas is released

Water Relation

Several investigations are available on the hyperactivity of antioxidative enzymes in various plants under Cu, Pb, Zn stress (Ali et al. 2003 Assche and Clijsters 1990). Nevertheless, fewer reports are available on the role of enzymatic antioxidant system in protecting plants from the toxic effects of reactive oxygen species (ROS) under Cr stress environment. This demonstrates the hypothesis that the antioxidant system, besides its function in detoxification, may also be a sensitive target of Cr toxicity in plants. Inside the cell, a reduction of Cr(VI) to Cr(III) owes to the formation of free radicals due to strong oxidative ability of Cr. (McGrath 1982 Cervantes et al. 2001). Thus, plants growing in a Cr(VI) stressed environment are prone to potential risk induced by ROS. Therefore, in response to Cr stress antioxidative defense systems, consisting of several non enzymatic and enzymatic mechanisms, are activated in the cell. One of the protective mechanisms is the enzymatic...

Steroids

When GC-MS is used, steroids are quite always derivatized, the most popular approach being the silylation, acylation (acetylation, perfluoroacylation) or oxime formation. (MSTFA) is often used as silylating agent in combination with ammonium iodine (NH4I) or trimethyliodosilane (TMIS) as catalyst, and dithiothreitol (DTE) as antioxidant. When LC-MS is used, derivatization is not mandatory but is sometimes used to enhance the signal or improve the specificity. Standard reference steroids are generally available in Sigma (St Louis, MO, USA), Steraloids (Wilton, NY, USA) and Research Plus (Bayonne, NJ, USA).

Background

Soil Plant Atmosphere Continuum

Environmental problems associated with metals are well reviewed as follows Pilon-Smits and Pilon, 2002 . Metals are present naturally in the Earth's crust at various levels (cf. Angelone and Bini, 1992 ). Mining, industry, and agriculture lead to accelerated release of metals into ecosystems, causing serious environmental problems and posing a threat to human health (e.g. Ross, 1994 ). Although many metals (Cu, Fe, Mn, Ni, Zn, etc.) are essential for cells, all metals are toxic at higher concentrations Marschner, 1995 . One reason metals may become toxic is that they may cause oxidative stress. Especially redox active transition metals, which can take up or give off an electron (e.g. Fe2+ 3+, Cu+ 2), can give rise to free radicals that cause damage Li and Trush, 1993 , but other metals can cause oxidative stress as well Baccouch et al., 1998 Cho and Park, 2000 .

HOO 8b NO

Photochemical Smog The Fate of the Free Radicals In later stages of photochemical smog formation, reactions that occur between two radicals are no longer insignificant, since their concentrations have become so high. Because their rates are proportional to the product of two radical concentrations, these processes are important when the radical concentrations are high i.e., they occur quickly under such conditions. Generally, the reaction of two free radicals yields a stable, nonradical product In summary, an episode of photochemical smog in a city such as Los Angeles begins at dawn, when sunlight initiates the production of hydroxyl radicals from the nitrous acid and from the ozone left over from the previous day. The initial input of nitric oxide and reactive hydrocarbons from morning rush-hour vehicle traffic reacts first to produce aldehydes (see Figure 3-4), the photolysis of which increases the concentration of free radicals and thereby speeds up the overall reaction. The...

Heavy Metals

True metal tolerance in plants could be, however, realized if metals are sequestered compartmentalized within the cell of different tissues so that metals are unable to react with metabolically active cellular substances (Volesky 1990 Barley et al. 2005 Rajamani et al. 2007). In many studies, a significant increase in the level of organic molecules and amino acids (such as histidine) has been reported to occur in roots of metal stressed plants (Hall 2002). These results suggest that the complexation of metals with these organic molecules and amino acids might be involved in reduced delivery of metals from roots to shoots and hence reduced tox-icity in aerial parts. However, once metals are transported to the aerial parts, there must be an effective mechanism to reduce their toxicity. As a first strategy, com-partmentation of metal ions in the vacuole is the most plausible method of cellular sequestration (Rajamani et al. 2007). In addition, most of the metals lead to the production of...

Metal Oxides

Modified forms of titanium dioxide have also found markets. Oxonica has developed and is selling a manganese-doped titanium dioxide that exhibits significantly enhanced UVA absorption and minimises the generation of free radicals resulting from the absorption of UV light by the titanium dioxide.47 49 This product is already being used commercially in sunscreens and cosmetics and is being evaluated for applications in coatings and plastics.

The Case of Selenium

Although Se is considered nonessential to higher plants, it may have beneficial biological functions . At low concentrations, it acts as an antioxidant and stimulates plant growth whereas at higher concentrations, it acts as a pro-oxidant, thus reducing the yield (Hartikainen, Xue, and Piironen, 2000) .

Ecological Partners

Since Se is toxic to many herbivores and pathogens, it may also affect pollination of plants with elevated Se. For plants, pollination is a key process in passing down genes and evolution through natural selection Parra-Tabla and Vargas 2004 . Elevated floral Se concentrations may act as a deterrent to Se sensitive pollinators, like it does too many herbivores. Alternatively, if pollinators benefit from Se (e.g. as a nutrient or antioxidant, or as a defense against pathogens or predators) or another characteristic unique to high-Se plants, Se may act as a cue to certain pollinators.

Silene vulgaris

Physiologic studies showed that Cu stress results in reduction of biomass production and root elongation (Schiller 1974 Wachsmann 1959), reduction of water content and increase of the osmotic value of the stem (Lolkema and Vooijs 1984 Schiller 1974), degeneration of chlorophyll and resulting chlorosis (Lolkema and Vooijs 1984), and disturbance of nitrogen uptake (Weber et al. 1991). According to de Vos et al. (1991, 1992, 1993), the primary effect of Cu toxicity is damage of the membrane permeability barrier in the root tip resulting in membrane lipids becoming oxidized by free radicals. Moreover, copper oxidizes all cellular thioles.

Nutrient Stress

Physiological and biochemical plant processes were affected by salt stress as a result of triggering premature nodule senescence along with a reduction in N-fixing ability of the nodules. In an experiment of 80 days, the plants were exposed to fairly high salinity regimes of 4, 6, 8 dS m-1 with and without mycorrhizal inoculation. Various parameters linked to nodule senescence were assessed like nodulation, leghemoglobin content, and nitrogenase enzyme activity measured as acetylene reduction activity (ARA). Two groups of antioxidant enzymes were studied (1) enzyme involved in detoxification of O2- radicals and H2O2 namely, superoxide dismutase, catalase and peroxidase, and (2) enzymes that are important components of the ascorbate glutathione pathway responsible for the removal of H2O2, namely, glutathione reductase and ascorbate peroxidase. The results of the experiment showed that AM significantly improved nodulation, leghemoglobin content and nitrogenase activity under salt...