BIOSYNTHESIS OF WITHANOLIDES IN ACNISTUS BREVIFLORUS

Article abstract of DOI:10.1016/S0031-9422(00)83022-8

Acnistus breviflorus; Solanaceae; withaferin A; withanolide; biosynthesis.Administration of <2-14C>mevalonolactone to excised leaves of Acnistus breviflorus produced labelled withaferin A and jaborosalactone A.The former was degraded leading to the isolation of glyceric acid from C-25-C-27 of the withanolide.These carbons represented only 2percent of the total radioactivity of withaferin A.The relative radioactivity of these carbons indicated that C-26 is directly derived from C-2 of mevalonolactone suggesting that the 25-pro-R-methyl group of cholesterol or any other sterol intermediate had been oxidized to form the lactone ring of the withanolide.The total radioactivity value found for C-25-C27 was much lower than the expected 20percent of the total value for the withanolide indicating that the side chain of the sterol precursor had been partially cleaved during the biosynthetic process.