Synthesis of Brassinosteroids of Varying Acyl Side Chains and Evaluation of Their Brassinolide-like Activity
作者:Shinya UESUSUKI、Bunta WATANABE、Shuji YAMAMOTO、Junko OTSUKI、Yoshiaki NAKAGAWA、Hisashi MIYAGAWA
DOI:10.1271/bbb.68.1097
日期:2004.1
Brassinosteroids containing various side chain moieties were synthesized and their activity was determined as the reciprocal logarithm of the ED50 (50% effective dose per plant in moles) in the rice lamina inclination assay using synergist indole-3-acetic acid (IAA). The introduction of a hydroxyl group in the α-position to the carbonyl group of the ester structure significantly enhanced the activity. 2α,3α-Dihydroxy-17β-[(2R,3S)-2-hydroxy-3-methylpentanoyl]oxy-B-homo-7-oxa-5α-androstan-6-one showed the highest activity, for which the pED50 was determined to be 10.5 under synergistic conditions with IAA. Under identical conditions, the pED50 values of brassinolide and castasterone were determined to be 13.6 and 12.3 respectively. With respect to the α-carbon of the acyl moiety, the R-form was 10 times more potent than the corresponding S-form. Substituting the terminal structure (Et) of the side chain to that of the most potent compound, brassinolide (i-Pr), did not increase the activity.
含有各种侧链基团的油菜素内酯被合成,其活性通过米种叶片倾斜测定法中的50%有效剂量(以摩尔计算每株植物的ED50)的倒数对数来确定,使用协同剂吲哚-3-乙酸(IAA)。在酯结构的羰基的α位引入羟基显著增强了活性。2α,3α-二羟基-17β-[(2R,3S)-2-羟基-3-甲基戊酰氧]基-β-同源-7-氧-5α-雄甾-6-酮表现出最高的活性,在与IAA的协同作用下,其pED50被确定为10.5。在相同条件下,油菜素内酯和蒽醇的pED50值分别为13.6和12.3。就酰基的α碳而言,R型的效能是对应的S型的10倍。将侧链的末端结构(Et)替换为最强化合物油菜素内酯(i-Pr)的结构并没有增加活性。