Isolation, structural elucidation and in vitro hepatoprotective activity of flavonoids from Glycyrrhiza uralensis.

Two new flavonoid glycosides, 2',4'-dihydroxydihydrochalcone-4-O-β-D-glucopyranoside (1) and medicarpin-3-O-β-D-apiofuranosyl (1 → 2)-β-D-glucopyranoside (2), together with 34 known flavonoids were isolated from the 75% EtOH extract of the dried roots of Glycyrrhiza uralensis Fisch. Their structures were elucidated on the basis of spectroscopic analyses. The flavonoids were classified into ten sub-types, namely, dihydrochalcone (1), pterocarpans (2-4), flavones (5-6), flavanones (7-11), chalcones (12-15), retro-chalcones (16-18), isoflavans (19-21), isoflavones (22-28), 3-arylcoumarins (29-30), and coumestans (31-36). The isolated flavonoids were evaluated for in vitro hepatoprotective activity against D-galactosamine-induced toxicity in human hepatoma HepG2 cells.