Xenobiotica 2010-01-01

Identification of cinobufagin metabolites in the bile of rats.

J Ning, T-H Wu, Y Tian, C-Y Wang, G Tian, B-J Zhang, K-X Liu, X-C Ma

Index: Xenobiotica 40(1) , 48-54, (2010)

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Abstract

Cinobufagin (1) is a major bufadienolide in ChanSu (a traditional Chinese medicine) with a wide range of pharmacological activities. In this paper, the in vivo metabolites of 1 in rats were studied. Nine metabolites were isolated from the bile of rats, and their structures were identified as: desacetylcinobufagin (2), 3-ketodesacetylcinobufagin (3), 3-epi-desacetylcinobufagin (4); 5beta-hydroxy-3-epi-desacetylcinobufagin (5), 1alpha-hydroxy-3-epi-desacetylcinobufagin (6), 12beta-hydroxy-3-epi-desacetylcinobufagin (7), 1beta-hydroxy-3-epi-desacetylcinobufagin (8), 1alpha,5alpha-dihydroxy-3-epi-desacetylcino-bufagin (9), and 2alpha, 5beta-dihydroxy-3-epi-desacetylcinobufagin (10), respectively, on the basis of widely spectroscopic studies including two-dimensional-nuclear magnetic resonance (NMR). Among them, metabolites 6-10 are new compounds. The results show that hydroxylation is the main reaction involved in metabolism of 1, and the preferred hydroxylation sites were C-1 and C-5.