Metabolism of aflatoxin B1 (AFB1), aflatoxin G1 (AFG1) and vitamin C intake by guinea pig liver preparation in vitro

Male and female guinea pigs weighing 150–200 g were divided into three groups, with equal number of males and females in each group. They were fed an experimental diet which varied as follows: group I, 0 mg vitamin C/g of diet; group II, 1.08 mg/g and group III, 5.4 mg/g, for 28 days. Twenty-four hours after the last feeding, liver slices and 9000 g supernatant were prepared from each group, according to sex, and used for enzyme assays. For the demethylation assay, enzyme activity expressed as amount of formaldehyde produced from AFB₁, or AFG₁/hr/g fresh liver was seen to increase with the two levels of ascorbic acid intake in females. Males showed an enhancement of activity only in group II and remained with the same production of formaldehyde as above in group III. Although in each dietary group, the activity was higher in males than in females the variation in the amount of formaldehyde produced from one group to another was higher with females than with male guinea pigs. However with both sexes, the production of formaldehyde from AFG₁, was greater than from AFB₁. For the hydroxylation assay, enzyme activity was expressed as amount of metabolites (a) and (b) produced. Compared to group II, which offered a control level of ascorbic acid, group I fed without vitamin C showed a decreased production of metabolite (a) and (b) with males and females. Moreover, high intake of ascorbic acid in group III decreased the production of metabolite (a) and (b) in males, while in female guinea pigs the reduction was observed only with (b).