Effects on Bioactivity due to C-5 Heteroatom Substituents on Synthetic 28-Homobrassinosteroid Analogs
作者:J Ramírez
DOI:10.1016/s0040-4020(00)00582-2
日期:2000.8.18
Five new 28-humobrassinosteroids have been synthesized, namely, (22R,23R)-5-fluoro-3 alpha,22,23-trihydroxy-5 alpha-stigmastan-6-one, (22R,23R)-5-fluoro-3 beta,22,23-trihydroxy-5 alpha-stigmastan-6-one (22R,23 R)-5-fluoro-2 alpha,3 alpha,22, 23-tetrahydroxy-5 alpha-stigmastan-6-one, (22R,23R)-3 alpha,5,21,23-tetrahydroxy-5 alpha-stigmastan-6-one and (22R,23R)-3 beta,5,22,23-tetrahydroxy-5 alpha-stigmastan-6-one. Their bioactivities were evaluated by the rice lamina inclination test. C-5 alpha Fluorinated analogs showed excellent in vitro bioactivity, also revealed at low doses, while C-5 alpha hydroxylated analogs resulted in an important decrease in bioactivity. Previously given explanations to justify the decreasing effect due to C-5 alpha electronegative groups should be revised. (C) 2000 Elsevier Science Ltd. All rights reserved.