Metabolism of 2′,4,4′-trihydroxychalcone in Amorpha fruticosa seedlings; structure and role of chalaurenol, a novel heterocyclic enol ether formed by enzymic oxidation

Abstract

Amorpha fruticosa seedlings contain two enzymes capable of catalysing reactions of 2′,4,4′-trihydroxychalcone. One is a chalcone-flavanone isomerase, which has been purified and occurs as two isozymes. More interestingly, the second is a peroxidase, which oxidises the chalcone (1; R¹= R²= OH, R³= H) to a novel labile quinol enol ether, chalaurenol (6), whose structure is established by chemical studies and X-ray diffraction of the 6–O-methyl ether (5). The possible origins and role of chalaurenol in plant metabolism are discussed.