Reduction in binding of [14C] aflatoxin B1 to rat liver macromolecules by phenobarbitone pretreatment.

Various dietary regimens have been shown to alter the acute and chronic toxicity of aflatoxin B₁ (AFB₁) in rats^1–4. Phenobarliitone (PB), an inducer of liver mixed function oxidases⁵ reduces the liver carcinogenioity of AFB₁ contaminated peanut meal⁶, decreases the LD₅₀ after an intraperitoneal injection of AFB₁ from 1 to 5 mg/kg (Gamer, Miller and Miller, unpublished) and reduces the inhibitory action of AFB₁ on rat liver ribonucleic acid synthesis⁷. The protective effect of PB contrasts with $\text{in vitro}$ findings that AFB₁ metabolism is increased by this enzyme-inducing agent, both to detoxification products such as aflatoxin B_2a⁸ and aflatoxin M₁⁹ as well as to AFB₁ 2, 3-oxide, the probable ultimate carcinogenic form of this compound¹⁰. To investigate this apparent discrepancy further the macro-molecular binding of [¹⁴C] AFB₁ after a single intraperitoneal injection has been studied in control and PB pretreated animals.