Noboru Hiraoka

Organ specific localization of flavonoids in Glycyrrhiza glabra L.

Glycyrrhiza glabra L. (licorice) contains not only glycyrrhizin, the sweet principle of licorice, but also diverse flavonoids in different organs of the intact plants. A large amount of glabridin, a prenylated flavonoid, was detected exclusively in the cork layer and the decayed part of the thickening roots. Large amounts of flavonoid glycosides, liquiritigenin glycosides and isoliquiritigenin glycosides, were mainly distributed in the woody part of the thickening roots. On the other hand, large amounts of flavonoids such as pinocembrin and licoflavanone were present on the outer surface of the young leaves, whereas isoquercitrin, a common flavonoid glycoside, was detected inside the leaves. Cultured cells of G. glabra produced no detectable amount of glabridin, liquiritigenin glycosides, isoliquiritigenin glycosides, pinocembrin, licoflavanone and isoquercitrin but produced formononetin, an isoflavonoid, which is commonly distributed in leguminous plants and in the underground and above-ground parts of G. glabra.

Flavonoid variation in the leaves of Glycyrrhiza glabra

Genistein, pinocembrin, prunetin, 6-prenylnaringenin, licoflavanone and wighteone were isolated from the leaves of Glycyrrhiza glabra collected on the west coast of Anatolia, whereas lupiwighteone was found only in the leaves of G. glabra growing in middle or east Anatolia. The G. glabra plants growing in different areas of Turkey could be classified into two types according to the occurrence of lupiwighteone in the leaf.

UDP-glucuronic acid: Triterpene glucuronosyltransferase activity in cultured licorice cells

Abstract UDP-glucuronic acid:triterpene glucuronosyltransferase activities for soyasapogenol B, soyasapogenol C, 24-hydroxyglycyrrhetinic acid and 24-hydroxyglycyrrhetinic acid methyl ester were detected in cultured licorice cells. The relative ratio of the activities for different substrates varied in culture strains. The pH dependency of the activity for soyasapogenol B was different from that for 24-hydroxyglycyrrhetinic acid methyl ester.