Polyphenols from plants used in traditional Indonesian medicine (Jamu): uptake and antioxidative effects in rat H4IIE hepatoma cells.

Phytochemical investigation of plants used in traditional Indonesian medicine (Jamu) yielded lignans (pinoresinol, 9 alpha-hydroxypinoresinol and salicifoliol), flavonoids (3-O-beta-(D)-glucopyranosyl-(1-->6)-beta-(D)-glucopyranosylkaempferol, luteolin and apigenin) and coumarins (coumarin, 8-hydroxycoumarin and 5-hydroxycoumarin). The beneficial effects of the respective plants for human health are thought to be associated with antioxidative activity. In the present study, the antioxidative capacity of the isolated compounds was determined in an in-vitro assay. Luteolin and kaempferol (cleavage product of 3-O-beta-(D)-glucopyranosyl-(1-->6)-beta-(D)-glucopyranosylkaempferol, which is thought to be formed in the intestine) showed strong antioxidant activity; pinoresinol and 9 alpha-hydroxypinoresinol showed only minor antioxidative effects. The coumarins, as well as apigenin and 3-O-beta-(D)-glucopyranosyl-(1-->6)-beta-(D)-glucopyranosylkaempferol were inactive. The antioxidative effects of luteolin, kaempferol and pinoresinol were further investigated in H4IIE rat hepatoma cells. A strong protective effect of kaempferol and luteolin was found against H2O2-mediated intracellular reactive oxygen species formation measured using the dichlorofluorescein assay and H2O2-mediated DNA strand breaks. Pinoresinol did not have a protective effect against H2O2-mediated DNA-damage, but in the dichlorofluorescein assay, an antioxidative effect was detectable. During studies with H4IIE cells, kaempferol, luteolin and pinoresinol were taken up by the cells within 60 min. The flavonoids were found to be relatively toxic at higher concentrations, while pinoresinol was less cytotoxic. In conclusion, kaempferol and luteolin, at low concentrations (< or = 50 microM), protect H4IIE cells against oxidative stress but are cytotoxic at higher concentrations; the biological effects of pinoresinol are less prominent in comparison. These results are important for the identification of pharmacologically active substances from traditional Indonesian medicinal plants.