Inhibition Of Aflatoxin B1-8,9-Epoxide Formation By Selected Ghanaian Vegetables
Aflatoxin exposure is a major public health problem because of the possible toxic effects on liver and other tissues. Biotransformation of aflatoxin B1 is closely linked to toxic and carcinogenic effects due to aflatoxin B1-8,9-epoxide formation. Thus, inhibition the epoxide formation is crucial. In this study, five Ghanaian vegetables, Corchorus olitorius, Xanthosoma mafaffa, Abelmoschus esculentus, Solanum torvum and Solanum aethiopicum were assessed for their inhibitory activities towards biotransformation of aflatoxin B1 to aflatoxin B1-8,9-epoxide using High performance liquid chromatography technique. Effects of the vegetables on the enzymes, CYP1A1/1A2 and GSTs which are involved in biotransformation of aflatoxin B1 to the epoxide were determined, as well as the antioxidant properties of the vegetables. Abelmoschus esculentus showed the strongest inhibitory activity (53.5%) towards aflatoxin B1-8,9-epoxide formation at the highest concentration tested. It also showed the strongest inhibition towards rat liver CY1A1/1A2 activity. There was no relationship between antioxidant and inhibitory activities of the vegetables towards the aflatoxin B1-8,9-epoxide formation. Therefore the mechanism of inhibition of the epoxide formation by the vegetables appears to be independent of antioxidant properties. Given the high level of exposure to aflatoxin B1 in some communities in Ghana, Abelmoschus esculentus could be a useful dietary component for inhibiting aflatoxin B1-8,9-epoxide formation and preventing its harmful effects in these communities. Further investigations are required to identify the active compound(s) in the vegetable responsible for inhibition of aflatoxin B1 biotransformation. Other foods and spices could also be screened analogously for epoxide inhibitory activity.