[A new C21 steroidal saponin from Cynanchum otophyllum and its anti-inflammatory activity]

Eight C21 steroidal compounds were isolated and purified from the chloroform extract of Cynanchum otophyllum by various modern separation techniques such as silica gel, ODS, and Sephadex LH-20 column chromatography, as well as preparative HPLC. Subsequently, the structures of these compounds were identified by high-resolution mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance as cynanototin B(1), caudatin(2), caudatin-3-O-β-D-cymaropyranoside(3), otophylloside B(4), qingyanshengenin-3-O-β-D-cymaropyranoside(5), qinyangshengenin-O-β-D-cymaropyranosyl-(1→4)-β-D-digitoxopyranoside(6), otophylloside A(7), and cynanotin H(8). Among them, compound 1 was a new C21 steroidal saponin. The anti-inflammatory activities of the isolated compounds were investigated. The results showed that compounds 1-3 and 5-6 exhibited good inhibitory activities against nitric oxide production in a lipopolysaccharide(LPS)-induced inflammation model of RAW264.7 murine macrophages, with IC_(50) values of(26.5±1.4),(16.5±1.0),(23.5±0.8),(21.5±1.0), and(18.5±0.95) μmol·L~(-1), respectively.