Synthesis and preliminary bioactivity evaluation of new pregnane brassinosteroid-like compounds

Seven new pregnane compounds bearing some representative A- and B-ring brassinosteroid functions, as well as hydrogen bond donor and acceptor ones on the D ring, were efficiently synthesized. The obtained compounds did not show remarkable plant growth-promoting activity in the radish hypocotyl elongation and cotyledon expansion bioassays, however, introducing oxygen and amino functions on the D ring led to an enhancement of the bioactivity. The 16β-functionalized pregnane brassinosteroid-like compounds were slightly more active than the 16α-functionalized ones.Key words: steroids, brassinosteroids, pregnane analogues.