Selenium suppresses the metabolism of benzo[a]pyrene by rat-liver extracts, and exerts a dual effect on its mutagenicity

Abstract

1. Liver homogenates from rats injected with 3 -methylcholanthrene were employed for metabolism of benzo[a]pyrene (BP) and in assays of aryl hydrocarbon hydroxylase (AHH) activity in vitro.

2. Sodium selenite inhibited AHH activity to a maximum of ∼70%. It suppressed the overall metabolism of benzo[a]pyrene; a distinct reduction in the products was evident on h.p.l.c. analysis.

3. Sodium thiosulphate also inhibited AHH activity by ∼ 47%. Inclusion of S₂O^2-₃ and SeO^2-₃, in combination, led to a cumulative inhibition of 87%.

4. The mutagenicity of BP in the Salmonella auxotroph reversion system (Ames test) was enhanced by SeO^2-₃ at concentrations below 0.2 mM. Above this level a significant anti-mutagenic effect was observed.