Structural Studies of Zoospore Attractants from Trachelospermum jasminoides var. pubescens : Taxifolin 3‐ O ‐glycosides

(2 S , 3 S )‐Taxifolin 3‐ O ‐arabinoside, a new dihydroflavonol glycoside, together with the known substances, (2 R , 3 R )‐taxifolin 3‐ O ‐arabinoside, astragalin, isoquercitrin, and cosmosiin, were isolated from the leaves of Trachelospermum jasminoides var. pubescens . Structural elucidation was carried out by spectroscopic methods, and the absolute configurations of C‐2 and C‐3 in taxifolin 3‐ O ‐arabinosides were determined on the basis of circular dichroism. Unlike the dihydroflavonol glycosides, (2 R , 3 R )‐taxifolin 3‐ O ‐glucoside and (2 R , 3 R )‐taxifolin 3‐ O ‐arabinoside, the novel (2 S , 3 S )‐taxifolin 3‐ O ‐arabinoside is not effective as a zoospore attractant of the plant pathogenic fungus Aphanomyces cochlioides . Copyright © 2005 John Wiley & Sons, Ltd.