presence of aflatoxins in smoked-dried fish sold in abeokuta, ogun ...

1.1.1 Physical Characteristics
According to ICRI (2000), Aspergillus flavus and Aspergillus parasiticus are mostly the molds
that produce Aflatoxin which are potent toxic, carcinogenic, mutagenic, immunosuppressive
agents. These fungi can produce their toxic compounds on almost any food that will support
growth. Among 18 different types of aflatoxins identified, major members which are metabolites
produced by these fungi are named AFB1, AFB2, AFG1, and AFG2, all which occur naturally.
Of the four, AFB1 is found in highest concentrations followed by AFG1, AFB2 and AFG2.
Aspergillus flavus only produces AFB1 and AFB2 and Aspergillus parasiticus produces these
same metabolites along with G1 and G2. Aspergillus flavus typically produces AFB1 and AFB2
whereas A. parasiticus produce AFG1 and AFG2 as well as AFB1 and AFB2. Four other
aflatoxins M1, M2, B2A, G2A which may be produced in minute amount were subsequently
isolated from cultures of A. flavus and A. parasiticus. A member of closely related compounds
namely aflatoxin GM1, parasiticol are also produced by A. flavus. Aflatoxin M1 and M2 are
major metabolites of aflatoxin B1 and B2 respectively, found in milk of animals that have
consumed feed contaminated with aflatoxins.
Description: Colourless to pale-yellow crystals. Intensely fluorescent in ultraviolet light,
emitting blue (aflatoxins B1 and B2) or green (aflatoxin G1) and green–blue (aflatoxin
G2) fluorescence, from which the designations B and G were derived, or blue–violet
fluorescence (aflatoxin M1).
Solubility: Very slightly soluble in water (10–30 µg/ml); insoluble in non-polar solvents;
freely soluble in moderately polar organic solvents (e.g., chloroform and methanol) and
especially in dimethyl sulfoxide (Cole & Cox, 1981).
Melting-points: see Table 1.
Absorption spectroscopy: see Table 1
1.1.2 Chemical Properties
Stability: Unstable to ultraviolet light in the presence of oxygen, to extremes of pH (< 3,
> 10) and to oxidizing agents.
3