Hepatic glucuronidation of isoneochamaejasmin a from the traditional Chinese medicine Stellera chamaejasme L. Root.
Isoneochamaejasmin A (INCA), a biflavonoid, is one of main active ingredients in the dried root of Stellera chamaejasme L., a widely used traditional Chinese medicine. In the present study, we identified the glucuronidation metabolite of INCA and characterized the UDP glucuronosyltransferases (UGTs) responsible for INCA glucuronidation. 7-O-glucuronide (M1) and 4'-O-glucuronide (M2) were identified by incubation of INCA with human liver microsomes (HLMs) in the presence of UDP glucuronic acid, and their structures were confirmed by high-resolution mass spectrometry and nuclear magnetic resonance analyses. Although INCA is a single enantiomer molecule, its M1 metabolite showed two equal-size peaks on a πNAP stationary phase but only one peak on a C(18) stationary phase, indicating that the 7-/7''- and 4'-/4'''-hydroxyl groups of INCA were in different spatial configurations relative to each other. Among the recombinant human UGT isoform test and correlation analysis, UGT1A1, UGT1A3, and UGT1A9 were found to mediate M1 formation, whereas only UGT1A3 mediated M2 formation. Kinetic studies showed obvious species differences between human, mouse, rat, dog, and pig liver microsomes. UGT1A1, HLMs, and human intestinal microsomes, but not human kidney microsomes, exhibited substrate inhibition for the formation of M1. UGT1A1-mediated formation of M1 showed a 6- and 11-fold higher V(max) than did UGT1A3- and UGT1A9-mediated formation of M1, respectively. The results of the relative activity factor assay showed that UGT1A1 contributed approximately 75% in the formation of M1. These findings collectively indicate that UGT1A1 is the major enzyme in the formation of M1, whereas UGT1A3 is the major enzyme in the formation of M2.
Department of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China (L.Y., M.Z., X.Z., Y.L., H.H., H.J., S.Z.); Institute of Materia Medica, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China (J.P., Y.C., S.C., J.C.); and Department of Pharmacy, 2nd Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China (Q.Z.).
Lushan
L
Yu
Jianbin
J
Pu
Minjuan
M
Zuo
Xia
X
Zhang
Yang
Y
Cao
Shifeng
S
Chen
Yan
Y
Lou
Quan
Q
Zhou
Haihong
H
Hu
Huidi
H
Jiang
Jianzhong
J
Chen
Su
S
Zeng
D000818:Animals; D044946:Biflavonoids / Q000737:chemistry / Q000493:pharmacokinetics*; D004285:Dogs; D020719:Glucuronides / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000378:metabolism*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000201:enzymology; D007668:Kidney / Q000201:enzymology / Q000378:metabolism; D008516:Medicine, Chinese Traditional; D051379:Mice; D008813:Mice, Inbred ICR; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism*; D018517:Plant Roots / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013237:Stereoisomerism; D029645:Thymelaeaceae / Q000737:chemistry*
D044946:Biflavonoids; D020719:Glucuronides; C530231:neochamaejasmin A; D014453:Glucuronosyltransferase