Glutathione conjugation of microsome-mediated and synthetic aflatoxin B1-8,9-oxide by purified glutathione S-transferases from rats.

Glutathione (GSH) conjugation of microsome-mediated and synthetic aflatoxin B1 (AFB1)-epoxide and styrene oxide has been investigated with purified GSH S-transferases (GSTs) from rats. Both styrene oxide and AFB1-epoxide were conjugated preferentially by millimicrons GSTs 3-3, 3-4 and 4-4 as compared to alpha GSTs 1-1, 1-2 and 2-2. The highest catalytic activity with styrene oxide conjugation was associated with GST 4-4. The highest catalytic activity with microsome-mediated AFB1-epoxide conjugation was observed with GST 3-3 whereas with the synthetic AFB1-epoxide conjugation was seen with GST 4-4. The catalytic activity of pi GST 7-7 was intermediate to millimicrons and alpha GSTs. It is suggested that GST 3-3 may play an important role in inactivation of AFB1-epoxide generated in vivo in the rat.