Secondary Metabolites Isolated from Dichloromethane Fraction of Rough Lemon Stem and Hepatoprotective Effect of Limonianin

Abstract

Aim: To investigate the dichloromethane fraction obtained from an aqueous methanol extract of green stems of Citrus jambhiri Lush. and evaluate the hepatoprotective effect of limonianin. Study Design: Isolation and identification of secondary metabolite and hepatoprotective activity of limonianin. Place and Duration of Study: Faculty of Pharmacy, Zagazig University and Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, between February 2012 and January 2014. Methodology: Psyllic acid, sinensetin, nobiletin, 6-demethoxytangeretin, limonianin, hesperetin, quercetin were isolated from the green stem of Citrus jambhiri. Their identity was unambiguously confirmed via different spectroscopic methods (UV, MS, 1H NMR, 13C NMR, H-COSY, HSQC and HMBC). The liver enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), superoxide dismutase (SOD), malondialdehyde (MDA) and total antioxidant capacity (TAC) were used to evaluate the hepatoprotective effect of limonianin. Results: Limonianin exhibited an equal or even better hepatoprotective activity than the known and medicinally used flavonoid mixture silymarin on human hepatoma cells (HepG2) against D-galactosamine-induced hepatotoxicity. Limonianin at concentration 5 µM exhibited a reduction of ALT, AST and MDA with 46.50, 42.10 and 24.36%, respectively while SOD and TAC were elevated with 38.56 and 391.67%, respectively compared with D-galactosamine (D-GaIN) treated cells. At concentration of 10 µM, limonianin shows elevation of SOD and TAC with 74.56 and 791.67%, respectively compared with silymarin (63 and 766.67%, respectively). Conclusion: The findings of this study showed that limonianin could be used as ideal hepatoprotective agent.