Synthesis and Biological Activity of 2,3-Diol Stereoisomers of 28-Homobrassinolide and Brassinolide

Abstract

As possible candidates for natural products and metabolites, three 2,3-diol stereoiosomers of 28-homobrassinolide (28-HBL) and those of brassinolide (BL) were synthesized and their biological activities evaluated by a modified dwarf rice lamina inclination assay, indicating that the biological activity decreased in the order 2α,3α-, 2α,3β-, 2β,3α- and 2β,3β-diol isomers of both the 28-HBL and BL series, suggesting that epimerization of configuration at the 2,3-diol position is an inactivation step in metabolism.