| Abstract: | Four B-ring oxygen-free trioxygenated xanthones, viz. 1-OH-2,3-(OMe)2-, 1,2,3-(OMe)3-, 1-OH-2,3- (OCH2O)-, 1-OMe-2,3-(OCH2O)-xanthone, two B-ring oxygen-free glucosyloxyxanthones, viz. 1-O-gl.-2-OH-3-OMe- and 1-O-gl.-2,3-(OCH20)-xanthone, and a pentaoxygenated xanthone, 1-OMe-2,3,6,7-(OCH2O)2-xanthone, have been isolated from the flowering top of Polygala triphylla. The xanthones have been characterized on the basis of chemical transformation, comprehensive spectral evidence, and by direct comparison where possible. This is the first report of occurrence of the glucosyloxyxanthones in nature. The biochemical significance of these chemical characters in higher plants is appraised. |
