Inhibitory effects of triterpenes isolated from Chuling (Polyporus umbellatus Fries) on free radical-induced lysis of red blood cells

Chuling, sclerotia of Polyporus umbellatus FRIES, has long been used for urological disorders in traditional medicine. In this study, we demonstrated that Chuling in vitro protects red blood cells from 2,2-azo-bis(2-amidinopropane)dihydrochloride (AAPH)-induced hemolysis. The inhibitory effect was dose-dependent at concentrations of 50 to 1000 microg/ml. Moreover, tests were carried out to identify the main ingredient of Chuling with scavenging effect on free radicals. Triterpene carboxylic acids isolated from the methanol extract of Chuling, namely, polyporusterone A and polyporusterone B, were found to have inhibitory activities against AAPH-induced lysis of red blood cells. The anti-hemolytic effect was significantly stronger in polyporusterone B compared with polyporusterone A. Furthermore, the ingestion of 150 mg of Chuling was associated with a significant increase in free-radical scavenging effect of plasma in rats.