A high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method employing electrospray ionization (ESI) has been developed for simultaneous determination of lancemaside A (3-O-beta-D-glucuronopyranosyl-3beta, 16alpha-dihydroxyolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl(1-->3)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl ester) and its metabolites in mouse plasma. When lancemaside A (60 mg/kg) was orally administered to mice, echinocystic acid was detected in the blood. T(max) and C(max) of the echinocystic acid were 6.5+/-1.9 h and 56.7+/-29.1 ppb. Orally administered lancemaside A was metabolized to lancemaside X (3beta, 16alpha-dihydroxyolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl(1-->3)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl ester) by intestinal microflora in mice, which was metabolized to echinocystic acid by intestinal microflora and/or intestinal tissues. Human intestinal microflora also metabolized lancemaside A to echinocystic acid via lancemaside X. These results suggest that the metabolism by intestinal microflora may play an important role in pharmacological effects of orally administered lancemaside A.
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