BIOSYNTHESIS OF QUERCETIN IN BUCKWHEAT: PART II

Abstract

Various C 14 -labelled compounds were administered to Fagopyrum tataricum. After allowing 24 hours for metabolism the quercetin was isolated and degraded, by a modified alkaline fusion, into phloroglucinol (ring A) and protocatechuic acid (ring B plus carbon 2). Uniformly labelled sucrose or C 14 O 2 (assimilated photosynthetically) formed quercetin equally labelled in the A and B rings, but sodium acetate-1-C 14 (or acetate-2-C 14 ) gave quercetin labelled almost entirely in ring A. Isotope competition experiments indicated meso-inositol and phloroglucinol were not precursors of ring A. The biosynthesis of quercetin from C 14 O 2 or acetate required the combined action of stem and leaves. Light was not required for synthesis of quercetin from acetate.