Three new spirostanic brassinosteroid analogues have been synthesized for the first time from diosgenin: (25R)-2alpha,3alpha-epoxy-5alpha-hydroxyspirostan-6-one (3), (25R)-2beta,3alpha,5alpha-trihydroxyspirostan-6-one (5) and (25R)-2beta-methoxy-3alpha,5alpha-dihydroxyspirostan-6-one (6). In the radish hypocotyl elongation and cotyledon expansion bioassay compound 3 showed plant growth promoting activity whereas 6 was shown to be phytotoxic.
steroids; brassinosteroid analogues; diosgenin
