Biochemical and Histopathological Effects of Aflatoxin on ...

2.0. Review <strong>of</strong> literature
2.1. Historical review
<strong>Aflatoxin</strong>s were first identified as etiological agents for animal disease
in the early 1960's, following an outbreak <strong>of</strong> deaths <strong>of</strong> turkey in Engl<strong>and</strong> <strong>and</strong>
elsewhere. The disease, termed Turkey X disease because <strong>of</strong> the then
unknown etiology was characterized by acute hepatic necrosis with bile duct
hyperplasia, lethargy, loss <strong>of</strong> appetite <strong>and</strong> death. The cause <strong>of</strong> the effects was
traced to Brazilian peanut meal that was used in a component <strong>of</strong> the poultry
ration (AIlcr<strong>of</strong>t <strong>and</strong> Carnaghan, 1963a). The toxic factors in the peanut meal,
namely aflatoxins were separated in to four distinct compounds: aflatoxin Bl,
Bz, G1 <strong>and</strong> Gz (Nesbitt etal, 1962; Sargeant et al,1961).
2.2. Structural diversity <strong>of</strong><strong>Aflatoxin</strong>s
Nearly all <strong>of</strong> the interest in aflatoxins has focused on AFBl, primarily
due to its extreme acute <strong>and</strong> chronic toxicity <strong>and</strong> its carcinogenic activity in
animals, in addition to its potential effects in humans. The toxic factors
isolated from feed were separated chromatographically into four distinct
compounds: aflatoxins Bl, Bz, G1 <strong>and</strong> Gz.The molecular formula indicated
that aflatoxins Bz <strong>and</strong> Gz (AFBz <strong>and</strong> AFGz) were dihydro derivatives <strong>of</strong> the
parent AFB1 <strong>and</strong> G1 respectively (Asao et al, 1963;Chang et al, 1963;
Cheung <strong>and</strong> Sill, 1964; Van der Merve et al, 1963; Van Dorp et al, 1963;
Van Soest <strong>and</strong> Peerdeman, 1964). AfIatoxins contain a coumarin nucleus
fused to a bifuran <strong>and</strong> either a pentanone (AFB 1 <strong>and</strong> Bz) or a six membered
lactone (AFG1 <strong>and</strong> Gz). AFB1 <strong>and</strong> G1 were more toxic to ducklings, rats, <strong>and</strong>
fish than either AFBz or AFG2 with AFB 1 being the most toxic (Wogan et al,
1971; Abedi <strong>and</strong> Scott, 1969). A similar pattern holds for its carcinogenic
potency, AFB 1 > AFG 1 > AFBz (Wogan et al, 1971; Ayes et al, 1971).
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