Two new phytoecdysteroids from the needles of Taxus canadensis

摘要

Two new phytoecdysteroids with a 20,22-acetal group were identified for the first time from the needles of the Canadian yew, Taxus canadensis. Their structures were characterized as ponasterone A 20,22-p-hydroxybenzylidene acetal (1) and ponasterone A 20,22-acetonide (2) on the basis of 1D, 2D NMR evidence and high-resolution FABMS analysis.