Effect of aflatoxins on oxidative phosphorylation by rat liver mitochondria.

ABSTRACT

The in vitro effect of aflatoxins M1, B1 and G1 on oxidative phosphorylation by rat liver mitochondria with succinate as substrate has been studied. All these toxins inhibit the electron transport chain at a 1-10-4 M concentration and the site of inhibition is between cytochrome b and cytochrome c or c1. Aflatoxin M1 (AFM1) uncouples oxidative phosphorylation at a concentration of 1-10-6 M and reduces the ADPO ratio, whereas aflatoxin B1 (AFB1) at 1-10-6 M concentration uncouples oxidative phosphorulation but does not affect the ADPO ratio. At a concentration of 1-10-5 M, AFB1 also decreases the ADPO ratio along with the uncoupling of oxidative phosphorylation. Aflatoxin G1 (AFG1) acts as an uncoupler at a relatively higher concentration of 1-10-4 M. Preincubation of mitochondria with these aflatoxins resulted in inhibition of respiration and uncoupling of rat liver mitochondria.