Stereospezifischer Einbau von (—)5.7.4′-Trihydroxyflavanon in Flavonoide und Isoflavone

Abstract

(±)5,7,4′-Trihydroxyflavanone-5-glucoside-[2-¹⁴C] was synthesized and the diastereomeric (+) and (-) glucosides were separated by paper chromatography. In buckwheat seedlings the incorporation rate of the (-) enantiomer into quercetin was 16 times higher and into cyanidin 3.6 times higher than that of the (+) compound. In chana seedlings (Cicer arietinum L.) the (-) compound was incorporated into biochanin A (5,7-dihydroxy-4′-methoxy-isoflavone) 14 times better than the (+) compound, whereas in agreement with earlier results the incorporation of both enantiomers into formononetin (7-hydroxy-4′-methoxy-isoflavone) was very low. The results prove the stereospecific incorporation of the naturally occuring (-) · 2 · S · 5.7.4′-trihydroxyflavanone into flavonoids and isoflavonoids. The incorporation of the (+) enantiomer is probably due to a racemization of this compound via the chalcone.