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.