油菜甾醇内酯类化合物结构与活性的相关性

比较了19种油菜甾醇内酯类似物和有关甾体化合物在水稻叶片倾斜及萝卜幼苗生长试验中的生物活性。表油菜甾醇内酯(24—Epi—BR)在两个系统中都具有很强的生物活性。C_2位失去羟基(香蒲甾醇)仅在水稻试验中有高活性,改变C_22位侧链结构(2α,3α双羟基—6—酮—23,24—双失碳—β—高-5α—胆烷酸甲酯)在萝卜试验中仍有活性。

Relationship between Structure and Biological Activity of Brassinolide Analogues

The biological activities of nineteen bras- sinolide analogues and related steroidal com- pounds were compared using two bioassay sys- tems: rice lamina inclination test and intact radish elongation test. In rice test, 24-epibras- sinolide exhibited the highest. activity, while in radish test compounds (12), (13) exhibited the highest (Table 1). The biological activity of 24-epibrassinolide increased with the increase of the corcentration from 0.0001 to 1 ppm in rice lamina inclination test (Fig. 2) and from 0.01 to 1 ppm in intact radish test (Fig. 3, 4). A compound which lost hydroxy group in 2- carbon position,such as compound (4), showed activity only in rice test, while compound(2) with modified side chain in 22-carbon position could significantly promote elongation of the cotyledon petiole and hypocotyl of intact radish (Table 1). Similar effects of brassinolide analogues on different varieties of rice were observed(Table 2). The relationship between the structure and bio- logical activity was discussed.