Protective effect of Centaurea pallescens Del. against CCl4-induced injury on a human hepatoma cell line (Huh7)

Through a hepatoprotective bioassay-guided fractionation of the methanol extract from Centaurea pallescens Del. (Asteraceae), a new acylated flavonoid triglycoside, 4'-methoxy kaempferol 3-O-[alpha-L-rhamnopyranosyl-(1 -> 3)-(2-O-E-p-coumaroyl)] beta-D-glucopyranoside-7-O-(4-O-E-p-coumaroyl) alpha-L-rhamnopyranoside (1) was isolated from the highly active aqueous fraction. In addition, six known compounds were isolated from both aqueous (2-3) and ethyl acetate soluble fractions (4-7). The structure of (1) was determined by comprehensive analysis of 1D and 2D NMR and mass spectral data. The protective effects of the methanol extract of C. pallescens and its fractions on the human hepatoma cell line were evaluated using Silymarin as a positive control. Hepatoprotection was assessed through determination of aspartate aminotransferase (AST), alanine transaminase (ALT), and superoxide dismutase (SOD) activities in addition to glutathione (GSH) levels before and after incubating the cells with carbon tetrachloride. Compound 1, the major constituent of the aqueous fraction, showed a significant cytoprotection at 100 mu g/mL as evidenced by decreasing ALT activity to 18.6 +/- 0.12, and enhancing SOD activity to 264.6 +/- 4.3 U/mL. Meanwhile, compound 2 at 10 mu g/mL decreased AST activity to 5.8 +/- 2.4 U/mL. Moreover, Compounds 2 and 3 at 1,000 mu g/mL significantly enhanced GSH levels. In conclusion, the protective effects of C. pallescens extract, its fractions and compounds 1-3 are concluded to be partly mediated by its antioxidant activity.