BIOSYNTHESIS OF QUERCETIN IN BUCKWHEAT: PART II

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Abstract
Various C14-labelled compounds were administered to Fagopyrum tataricum. After allowing 24 hours for metab-olism 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 C14O2 (assimilated photos ynthetically) formed quercetin equally labelledin the A and B rings, but sodium acetate-l-C14 (or acetate-2-C14) 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 C14O2 or acetate required the combined action of stem and leaves. Light was not required for synthesis of quercetin from acetate.