Inhibitory effect of Nymphaea pubescens Willd. flower extract on carrageenan-induced inflammation and CCl4-induced hepatotoxicity in rats

Nymphaea pubescens Willd. is used as ingredient of ethnic diet and folk medicine in South-East Asia. The water (NPW), methanol (NPM) and chloroform (NPC) extracts of N. pubescens flowers were investigated for NO, O2- and DPPH radical scavenging and iron chelating activities in vitro. NPW was found to be the most potent free radical scavenger (EC50 < 100 μg/mL) whereas NPC did not show EC50 at 500 μg/mL. Therefore, NPW was selected for further studies on anti-inflammatory and hepatoprotective activities, using standard in vitro and in vivo models. NPW exhibited inhibition of nitrogen radical generation in LPS-activated macrophages (IC50 = 75.5 μg/mL) through suppression of iNOS protein, with no associated toxicity in the cells. Further, 500 mg/kg of NPW reduced rat paw edema by ∼50% after 6 h of carrageenan administration. Hepatoprotective activity of NPW was also evaluated in vivo on CCl4-induced hepatotoxicity model in rats. NPW treatment (500 mg/kg/day for ten days) attenuated CCl4-induced increase in serum enzymes, viz. alanine and aspartate aminotransferases (ALT and AST) and bilirubin. Also, glutathione and superoxide dismutase (SOD)-levels were restored towards normalcy in the liver of CCl4-treated rats, indicating the hepatoprotective role of NPW, which was found to contain a fair amount of flavonoids, phenolics, and saponin constituents.