ON BIOGENESIS OF FLAVONE O-GLYCOSIDES AND C-GLYCOSIDES IN LEMNACEAE

14C-Labeled apigenin, luteolin, orientin, isoorientin, and isovitexin were obtained either directly or by hydrolyzing the glycosides obtained from Spirodela and Lemna species which had been cultured on media containing phenylalanine-1-14C. The 14C-labeled flavones were introduced into the growth media for S. polyrhiza, S. oligorhiza and L. minor plants. When the extracts from these plants were chromatographed and the two-dimensional chromatograms examined autoradiographically, radioactivity was detected in O-glycosylated and O-methylated flavones. However, radioactivity was not detected in flavones containing new C-glycosyl linkages. The data suggest that plants in the Lemnaceae O-substitute flavones but do not C-glycosylate them. Moreover, evidence was obtained that flavones containing a 4′-monohydroxy B-ring can be oxidized to flavones with a 3′,4′-dihydroxy B-ring. None of the 14C-flavones was incorporated into any of the anthocyanins known to occur in the Lemnaceae. Isoorientin 3′-methyl ether and an O-β-d-glucoside of chrysoeriol were detected for the first time as constituents of L. minor. © 1970.