脱落酸(Abscisic acid, ABA)对映异构体的生物活性比较

 采用新方法精制脱落酸(ABA)异构体试样,改变以往靠光学离析法分离racemic型(SR)-(±)-ABA,提高了(S)-(+)-ABA与(R)-(-)-ABA两镜像体纯度。抑制生长试验和残留量分析结果表明:天然型(S)-(+)-ABA活性,显着高于非天然型(R)-(-)-ABA或(SR)-(±)-ABA活性。抑制莴苣种子发芽50%的活性强度(S)-(+)-ABA约是(R)-(-)-ABA的5倍,(SR)-(±)-ABA介于二者之间。抑制萝卜下胚轴生长试验,最显着有效期2～6天,(6天后差异渐小,8日甚微),生理作用期约为一周,(S)-(+)-ABA活性是(R)-(-)-ABA的3.6倍。差异原因可能是两异构体分子立体结构不同所致。

Comparison of Biological Activity Between Natural(S)-( )-ABA and Non-Natural(R)-(-)-ABA

Adopting new method to make the isomeride sample of ABA is far better than the old optical resolution of separating the racemic (SR)-(±)-ABA, thus the enantiomer purity of both (S)-(+)-ABA and (R)-(-)-ABA can be greatly upgraded.An experiment was conducted on the inhibition of hypocotyl growth of radish and gennination of lettuce seeds,as well as the inhibition of root growth by using (S)-(+),(RS)-(±),and(R)-(-)-ABA, and HPLC was used to analyse the ABA residues in radish hypocotyl. The result showed that the activity of natural (S)-(+)ABA was significantly higher than that of (R)-(-)-ABA or (SR)-(±)-ABA.The inhibition of 50% germination of lettuce seeds by using (S)-(+)-ABA was 5 time than of (R)-(-)-ABA. While the inhibition of (SR)-(±)-ABA is just the average of the fonner two.The inhibition of hypocotyl growth of radish seedling showed that all individual isomerides were easily absorbed(Assimilated) by plants. The most evident effect of inhibition usually lasted 2～6 days and after 6th day the inhibition variation ininhibitive action among plants became less. The activity of (S)-(+)-ABA was 4 times than that of (R)-(-)-ABA. The difference of stereo structure probably resulted in the difference in biologically activity of two enantiomers.Accordingly, the use of natural (S)-(+)-ABA has great significance.