RESUMO
Salmonella typhimurium TA 100 was mutagenized with photoactivated aflatoxin B1 (AFB1) and AFB2. Levels of mutagenesis induced by AFB1 correlated with levels of in vitro covalent binding of [3H]AFB1 to calf thymus DNA. The same phenomenon was observed with AFB2. Photoactivated AFB1 induced lethality in the mutagenized cultures, and AFB2 failed to do so. Extraction of nucleic acids from cultures mutagenized by photoactivated or metabolically activated [3H]AFB1 revealed that: (a) in situ levels of [3H]AFB1 binding to DNA were proportional to induction of mutational and lethal events in both cases; (b) mammalian metabolism and photoactivation produced AFB1:DNA lesions possessing comparable lethality and mutagenicity; and (c) [3H]AFB1 binding levels to bacterial RNA did not correlate with mutagenesis and lethality.
Assuntos
Aflatoxinas/toxicidade , Carcinógenos/toxicidade , Mutagênicos , Mutação , Aflatoxina B1 , Aflatoxinas/metabolismo , Animais , Biotransformação , Bovinos , DNA/metabolismo , Microssomos Hepáticos/metabolismo , Testes de Mutagenicidade , Fotoquímica , Ratos , Salmonella typhimurium/efeitos dos fármacos , TimoRESUMO
The mutagenesis of Salmonella typhimurium TA100 and covalent binding in vitro of photoactivated aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) were investigated. Covalent binding levels of 1140, 225, 330 and 8 pmol aflatoxin per mumol nucleotide phosphate were obtained for AFB1, AFG1, AFB2 and AFG2, respectively, at 50 microM mycotoxin after 2 h of irradiation. Mutant frequencies to histidine prototrophy wre 97, 19, 49 and 0 x 10(-6) for AFB1, AFG1, AFB2 and AFG2 respectively, after 2 h irradiation at 100 microM mycotoxin in the surviving fraction of the mutagenized cultures. Toxicity to Salmonella was 0.59, 0.03, 0.31 and 0 lethal hits under the conditions specified for mutagenesis for AFB1, AFG1, AFB2 and AFG2, respectively.
