Biochemical and Histopathological Effects of Aflatoxin on ...

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4.0 Introduction Chemical compounds <strong>and</strong> reactions capable <strong>of</strong> generating potential toxic oxygen species / free radicals are referred to as pro-oxidants. On the other h<strong>and</strong>, compounds <strong>and</strong> reactions disposing <strong>of</strong>f these species, scavenging them, suppressing their formation or opposing their actions are called anti oxidants. In a normal cell, there is an appropriate pro-oxidant: antioxidant balance. However, this balance can be shifted toward the pro-oxidant when production <strong>of</strong> oxygen species is increased or when levels <strong>of</strong> anti-oxidants are diminished. This state is called oxidative stress <strong>and</strong> can result in serious cell damage if the stress is massive or prolonged (Irshad <strong>and</strong> Chaudhuri, 2002). The" oxidant / free radicals are species with very short half-life, high reactivity <strong>and</strong> damaging activity towards biomolecules like proteins, DNA "<strong>and</strong> lipids. Free radicals are formed by hemolytic cleavage <strong>of</strong> a covalent bond <strong>of</strong> a molecule, by the loss <strong>of</strong> a single electron from a normal molecule or by the addition <strong>of</strong> a single electron to a normal molecule. Most <strong>of</strong> the molecular oxygen consumed by aerobic cells during metabolism is reduced to water by using cytochrome oxidase in mitochondria. However, when oxygen is partially reduced it becomes "activated" <strong>and</strong> reacts readily with a variety <strong>of</strong> biomolecules. This partial reduction occurs in one-electron steps, by addition <strong>of</strong> one, two <strong>and</strong> four electrons to O2, which leads to successive formation <strong>of</strong> reactive oxygen metabolites (ROMs). These are five possible . species: O 2 '- (superoxide anions), H0 2 ' (hydroperoxyl radical), peroxide ion (H0 2 .) , H20z (hydrogen peroxide) <strong>and</strong> 'OH ( hydroxyl radical). 29
4.1 Source <strong>of</strong> Reactive Oxygen Species The exogenous sources <strong>of</strong> Reactive Oxygen Species (ROS) include electromagnetic radiation, cosmic radiation, cigarette smoke, car exhaust, UV Light, Ozone (0 3 ) <strong>and</strong> low wavelength electromagnetic radiation. Similarly the endogenous sources <strong>of</strong> ROS are mitochondrial electron transport chain, respiratory burst by phagocytes, beta oxidation <strong>of</strong> fat in peroxisome, auto-oxidation <strong>of</strong> amino acids, catecholamines <strong>and</strong> hemoglobin. Superoxide anion radical (02) regulates metabolites capable <strong>of</strong> signaling <strong>and</strong> communicating important information to the cellular genetic machinery ( Me Cord, 2000). Hydroxyl radical is another damaging radical with a half-life <strong>of</strong> 10- 5 sec <strong>and</strong> produced from H202 <strong>and</strong> O2 by Haber - Weiss reaction (Beauchamp <strong>and</strong> Fridovich, 1970). Some HO may be produced from hypochlorous acid in phagocytic cells. Similarly, H202 is a relatively stable, poorly reactive non-radical oxygen species, which easily crosses cell membrane <strong>and</strong> attacks different rates by converting into -HO. This is produced by dismutation <strong>of</strong> O2 by superoxide dismutase (SOD) <strong>and</strong> finally meets many fates including its reduction to water. H 202 is also involved in the generation <strong>of</strong> free radicals in presence <strong>of</strong> transitional metal ions. 4.2 Damage by Reactive Oxygen Species (ROS) Even without pollution <strong>and</strong> xenobiotic metabolism there is a constant production <strong>of</strong> reactive oxygen species in all living cells. Due to the high reactivity <strong>of</strong> reactive oxygen species most components <strong>of</strong> cellular structure <strong>and</strong> functions are likely to be targets <strong>of</strong> oxidative damage (Kappus, 1987). 30
Page 1: BIOCHEMICAL AND HISTOPATHOLOGICAL E
Page 6 and 7: CHAPTER 1 Introduction CHAPTER2 Rev
Page 8 and 9: Estimation ofAST E
Page 10 and 11: 1.0 Introduction Aquaculture today
Page 12 and 13: distribution of ma
Page 14 and 15: C H A P T E R Review of</st
Page 16 and 17: 2.3 Structures of
Page 18: animals. As is the case with other
Page 21 and 22: When the dose was increased ten fol
Page 23 and 24: neoplastic cells and</stron
Page 25 and 26: 2.10 b. Carbohydrate and</s
Page 27 and 28: Any discussion in multistage carcin
Page 29 and 30: 3.0 Introduction Fungi grow on pell
Page 31 and 32: imperative to use a method which is
Page 33: MgS04.7H20 FeS0 4.7H20 Distilled wa
Page 36 and 37: 3.3.6 Preparation of</stron
Page 38 and 39: Aflatoxin biosynth
Page 40 and 41: The solubility of
Page 44 and 45: Generalized Scheme for Oxidative In
Page 46 and 47: Initiation and pro
Page 49 and 50: (d) Glutathione peroxidase (E.C.l.l
Page 51 and 52: 4.9.l.b Estimation of</stro
Page 53 and 54: Preparation of Tis
Page 55: Procedure Tissues homogenates were
Page 60: was 0.559. Concentration 0.375 ppm
Page 72 and 73: (Madhusudhanan et al, 2000). But in
Page 74: 5.0. Introduction Structural <stron
Page 79 and 80: PLATE 8.5 Section of</stron
Page 81: The GlIb section of</strong
Page 85 and 86: All experimental fish appeared norm
Page 87 and 88: lesion, serving as precursors <stro
Page 89 and 90: C H A P T E R 6 Aflatoxin</
Page 91 and 92: Biochemically, afl
Page 95:
}.2 Materials and
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incubation, 0.2ml of</stron
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times. Waited for 10 minutes till a
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2. Buffer: Sodium carbonate- bicarb
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added to O.Sml of
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Procedure 2g of fl
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diluent solution. Using a commercia
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Parameter Treatment Urea ( J1 moles
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4 3 .... Cl 2 1 o Control 0.375ppm
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300 250 200 "Cm150 E 100 50 o Contr
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Treatment Parameter P value Cholest
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I Source of Variat
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113 type seem to take an active rol
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C H A P T E R 7 Electrophoretic Ana
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116 Among the many biornarkers the
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118 refrigerator for some time to e
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7.1.2b Reagents for electrophoresis
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7.1.2c Preparation of</stro
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3) 10% SDS 4) 6 M Sodium chloride 5
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) Serum Protein (Non SDS Page) 129
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fragments of simil
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C H A P T E R 8 Effect of</
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may result from destabilization <st
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2) Buffer: Citrate buffer (O.05M) <
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Source of Variatio
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Groups Pvalue Control vs 0.375ppm N
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8.1 Studies on the Erythrocyte Memb
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4) To O.lml of the
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8.ID Discussion The results obtaine
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a) Preparation of
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Source of Variatio
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8.3 Studies On Muscle Retention 8.3
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Detection: Waters 440 Absorbance at
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8.3C Results The results are presen
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9.0 Summary The present study was u
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• Aflatoxin resi
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BIBLIOGRAPHY Abedi A Hand</
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Bruenger, A and Gr
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Egmond H P V and W
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Hendricks J D, Wales J H, Sinnhuber
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Lowry 0 H, Rosenbrough N J, Farr A
Page 202 and 203:
New M B (1987). Feed and</s
Page 204 and 205:
Saber N A (1995). Depression <stron
Page 206 and 207:
Soni KB, Rajan A and</stron
Page 208 and 209:
Verma R J, Kolhe A Sand</st
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