Antioxidant and Preventive Effects of Extract from Nymphaea candida Flower on In Vitro Immunological Liver Injury of Rat Primary Hepatocyte Cultures

Nymphaea candida is traditional Uighur medicine that is commonly used to treat head pains, cough, hepatitis and hypertension in Xinjiang of China. In this article, the extract of N. candida was measured for antioxidant activity, using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging assay and reducing power determination, and compared with those of the positive controls of butylated hydroxytoluene (BHT) and gallic acid (GA). The active extract was further purified by liquid-liquid partition to afford four fractions, of which the ethyl acetate-soluble (EA) fraction (NCE) exhibited the strongest antioxidant capacity with IC(50) value of 12.6 μg/mL for DPPH. Thirteen phenolic compounds were isolated from this fraction, and they all showed significant antioxidant activities in DPPH model system. Furthermore, NCE showed potent antioxidant capacity with IC(50) value of 59.32 μg/mL, 24.48 μg/mL and 86.85 μg/mL, for O(2) (−), ·OH and H(2)O(2) radicals, respectively. Moreover, NCE on BCG plus LPS-induced immunological liver injury was evaluated using primary cultured rat hepatocytes. NCE produced significant hepatoprotective effects as evidenced by decreased supernatant enzyme activities (AST—aspartate transaminase, P < .01; ALT—alanine transferase, P < .01) and nitric oxide (NO, P < .01) production. These results revealed the in vitro antioxidant and hepatoprotective activities of NCE against immunological liver injury. Further investigations are necessary to verify these activities in vivo.