Hepatoprotective principles from the flowers of Tilia argentea (Linden): Structure requirements of tiliroside and mechanisms of action

The methanolic extract from the flowers of Tilia argentea (linden) was found to show a hepatoprotective effect against D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced liver injury in mice. By bioassay-guided separation using in vitro D-GalN-induced damage to hepatocytes, five flavonol glycosides were isolated as the hepatoprotective constituents of the methanolic extract. Tiliroside. the principal flavonol glycoside. strongly inhibited serum GPT and GOT elevations at doses of 25-100 mg/kg (p.o.) in D-GalN/LPS-treated mice. By comparing the inhibitory effects of tiliroside with those of its components alone. the kaempferol 3-O-beta-D-glucopyranoside moiety was found to be essential for the activity, and its effect was suggested to depend on the inhibition of tumor necrosis factor-alpha (TNF-alpha) production. decreased sensitivity of hepatocytes to TNF-alpha. and on the protection of hepatocytes against D-GalN. (C) 2002 Elsevier Science Ltd. All rights reserved.