Bioactive Constituents from Chinese Natural Medicines.XVII.~1)Constituents with Radical Scavenging Effect and New Glucosyloxybenzyl 2-Isobutylmalates from Gymnadenia conopsea

摘要

The methanol-eluted fraction of the methanolic extract from the tubers of Gymnadenia conopsea was found to show radical scavenging activities for DPPH and super oxide anion(~(centre dot)O_2~-)radicals.Three new glucosyloxybenzyl 2-isobutylmalates,gymnosides VIII,IX,and X,were isolated from this natural medicine together with 58 known constituents.The stereostructures of gymnosides were elucidated on the basis of chemical and physico-chemical evidence.In addition,the phenanthrene and dihydrostilbene constituents showed radical scavenging activities and suggested the following structural requirements on radical scavenging activitiesa)phenanthrenes:1)dihydrogenation at the 9,10-positions enhances the activities,2)the 1 or 3-p-hydroxybenzyl group enhances the activitiesb)dihydrostilbenes:1)methylation of the 3'-position reduces the activities,2)the 2-and/or 6-p-hy-droxybenzyl groups enhance the activities.