Direct evidence for quinone-quinone methide tautomerism during tyrosinase catalyzed oxidation of 4-allylcatechol.

The hapatotoxicity of safrole and related compounds has been attributed to the electrophilic compounds generated from the oxidation of these chemicals. In this paper, for the first time using quasi pre-steady state conditions, we present direct evidence for the rapid production of electrophilic allyl o-quinone and its tautomerization to more stable and reactive vinyl p-quinone methide during both the enzyme catalyzed and chemical mediated oxidation of 4-allylcatechol, an in vivo product of safrole metabolism.