Studies on metabolism and toxicity of styrene. IV. 1-Vinylbenzene 3, 4-oxide, a potent mutagen formed as a possible intermediate in the metabolism in vivo of styrene to 4-vinylphenol.

1-Vinylbenzene 3,4-oxide, a putative intermediate in the metabolism of styrene to 4-vinylphenol, was synthesized and examined for its obligatory intermediacy to the phenol, its physical properties, and its mutagenicity toward Salmonella typhimurium TA98 and TA100. The 3,4-oxide had a half-life of 4.3 sec at pH 7.4 in an aqueous solution, and yielded 4-vinylphenol quantitatively without concomitant formation of any trace amount of 3-vinylphenol. The 3,4-oxide had a potent mutagenicity toward the TA100 bacteria but not toward the TA98 strain, whereas it showed a potent cytotoxicity to both of them His+ revertant colonies induced by the 3,4-oxide were 7233/plate at a total dose of 1.0 micromole/plate when it was applied in a sequential manner to the bacterial suspension during the pre-incubation of the testing system. Under the same conditions, benzo[a]pyrene 4,5-oxide and phenyloxirane showed 1283 and 1657 of His+ revertant colonies/plate at 19 nmoles and 10 micromoles/plate, respectively, as the maximal activities. The isomeric arene oxide, 1-vinylbenzene 1,2-oxide, had a longer half-life (1.63 min) than the 3,4-oxide at pH 7.4 in aqueous solution and was specifically rearranged to 2-vinylphenol. The 1,2-oxide also showed more potent mutagenicity to the TA100 strain bacteria than phenyloxirane but weaker than the 3, 4-oxide. 4- and 2-vinylphenols were neither mutagenic nor cytotoxic to the bacteria at concentrations ranging up to 4 micromoles/plate.