Volume 104, Issue 10 pp. 3557-3564
RESEARCH ARTICLE

In Vitro Evaluation of the Effect of 7-Methyl Substitution on Glucuronidation of Daphnetin: Metabolic Stability, Isoform Selectivity, and Bioactivity Analysis

Si-Cheng Liang

Si-Cheng Liang

Second Affiliated Hospital of Dalian Medical University, Dalian, China

Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

University of Chinese Academy of Sciences, Beijing, China

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Guang-Bo Ge

Guang-Bo Ge

Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

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Yang-Liu Xia

Yang-Liu Xia

Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

University of Chinese Academy of Sciences, Beijing, China

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Jiang-Wei Zhang

Jiang-Wei Zhang

Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

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Xiao-Yi Qi

Corresponding Author

Xiao-Yi Qi

Second Affiliated Hospital of Dalian Medical University, Dalian, China

Telephone: +86-411-84379317; Fax: +86-411-84676961; E-mail: [email protected]; Telephone: +86-411-84379317; Fax: +86-411-84676961; E-mail: [email protected]Search for more papers by this author
Cai-Xia Tu

Cai-Xia Tu

Second Affiliated Hospital of Dalian Medical University, Dalian, China

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Ling Yang

Ling Yang

Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

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First published: 17 June 2015

Abstract

The C-8 phenol group is essential to exert the bioactivities of daphnetin, but it is readily conjugated with glucuronic acid prior to excretion. In this study, daphnetin-7-methylether (7M-DNP) was used to investigate the effect of 7-methyl substitution on daphnetin glucuronidation in human/rat liver (HLM/RLM) and intestine (HIM/RIM) microsomes, and recombinant UDP-glucuronosyltransferases (UGTs). Compared with daphnetin, the Vmax/Km values of 7M-DNP via 8-O-glucuronidation were 2.1-fold lower in HLM, 1.7-fold lower in HIM, and 2.4-fold lower in RLM, suggesting an improvement in metabolic stability. Different from daphnetin 8-O-glucuronidation exclusively catalyzed by UGT1A6 and UGT1A9, UGT1A1, -1A3, -1A7, -1A8, and -1A9 showed glucuronidation activity toward 7M-DNP. Kinetics studies, chemical inhibition, and the relative activity factor approach were used to demonstrate that UGT1A9 was mainly responsible for the reaction in HLM, whereas UGT1A1 was a primary contributor in HIM. The Vmax/Km values of 7M-DNP glucuronidation in HLM and HIM were 0.61–0.74-fold lower than those of rat, suggesting the differences between the two species. The bioactivity analysis demonstrated that 7M-DNP had an anti-inflammatory activity comparable to that of daphnetin. These findings indicated that the outcomes of 7-methyl substitution on daphnetin might be positive, but this should be confirmed in future in vivo studies. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3557–3564, 2015

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