Naturally Occurring Quinones as Bioreductive Alkylating Agents
Bioreductive alkylation is the term used to describe the effect of those compounds which express their mode of biological action as alkylating agents, but do so subsequent to their reduction in vivo.1 That is, they are pro-drugs which are activated by a bioreduction. Quinones are a class of compounds ideally suited to function as the reducible moiety of bioreductive alkylating agents since their facile reduction in vivo and in vitro to the corresponding hydro-quinones is a well known and extensively studied reaction.2 If the quinone is further substituted with a side-chain bearing a leaving group X at the 1-position of the substituent, then quinonemethide formation can result by an elimination of HX from the hydroquinone.2,3 The reactive quinonemethide is suggested as the discrete alkylating agent and functions as such by a Michael addition of a biologically important nucleophile (Nu-:DNA, protein, carbohydrate, etc.) to the enone of the methide. This postulate is represented by the sequence of reactions outlined in Scheme . i.e., 1 → 2 → 3 → 4.
KeywordsSodium Dithionite Reductive Elimination Carminic Acid Hypoxic Tumor Cell Quinone Methides
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