title: Mechanism-based inhibition of Alantolactone on human cytochrome P450 3A4 in vitro and activity of hepatic cytochrome P450 in mice.
abstract: BACKGROUND
  Alantolactone (AL), one of the main active ingredients in Inula helenium L., has been included in various prescriptions of traditional Chinese medicine. The effects of AL on cytochrome P450 (CYP450) were still unclear. This study evaluated the inhibitory effect of AL on cytochrome P450s in vitro and in vivo.
  
  
  METHODS
  The inhibitory effects of AL on the CYPs activity were evaluated in human liver microsomes (HLMs) and recombinant cDNA-expressed enzymes incubation system, and then determined by LC-MS/MS based CYPs probe substrate assay. C57BL/6 mice were treated AL orally (0, 25, 50, 100 mg/kg) for 15 days. The inhibitory effects of AL on major Cyps in mice were examined at both the mRNA and enzyme activity levels.
  
  
  RESULTS
  AL showed a potent inhibitory effect on CYP3A4 activity with IC50 values of 3.599 (HLMs) and 3.90 (recombinant CYP3A4) μM, respectively. AL strongly decreased CYP3A4 activity in a dose-dependent but not time-dependent way in HLMs. Results from typical Lineweaver-Burk plots showed that AL could inhibit CYP3A4 activity noncompetitively, with a Ki value of 1.09 μM in HLMs. Moreover, activity of CYP2C19 could also be inhibited by AL with IC50 of 36.82 μM. Other CYP450 isoforms were not markedly affected by AL. The inhibition was also validated by in vivo study of mice. AL significantly decreased mRNA expression of Cyp2c and 3a family.
  
  
  CONCLUSIONS
  The study indicates that herb-drug interaction should be paid more attention between AL and drugs metabolized by CYP3A4.
authors: Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, PR China; Hunan Province Cooperation Innovation Center for Molecular Target New Drug Study, Hengyang 421001, PR China.
authors: Chong-Zhen
authors: CZ
authors: Qin
authors: Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, PR China; Hunan Province Cooperation Innovation Center for Molecular Target New Drug Study, Hengyang 421001, PR China.
authors: Qiao-Li
authors: QL
authors: Lv
authors: Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, PR China; Hunan Province Cooperation Innovation Center for Molecular Target New Drug Study, Hengyang 421001, PR China.
authors: Na-Yiyuan
authors: NY
authors: Wu
authors: Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, PR China; Hunan Province Cooperation Innovation Center for Molecular Target New Drug Study, Hengyang 421001, PR China.
authors: Lin
authors: L
authors: Cheng
authors: Department of Molecular Biology and Human Genetics, Tzu Chi University. No 701 Sec 3 Chun Yang Rd. Hualian City, Taiwan.
authors: Yun-Chen
authors: YC
authors: Chu
authors: Department of Obstetrics and Gynecology, Buddhist Tzu Chi General Hospital, Tzu Chi University, Hualien, Taiwan; Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan.
authors: Tang-Yuan
authors: TY
authors: Chu
authors: Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, PR China; Hunan Province Cooperation Innovation Center for Molecular Target New Drug Study, Hengyang 421001, PR China.
authors: Lei
authors: L
authors: Hu
authors: Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, PR China; Hunan Province Cooperation Innovation Center for Molecular Target New Drug Study, Hengyang 421001, PR China.
authors: Yu
authors: Y
authors: Cheng
authors: Institute of Life Sciences, Chongqing Medical University, Chongqing 400016, China.
authors: Xue
authors: X
authors: Zhang
authors: Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, PR China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, PR China; Hunan Province Cooperation Innovation Center for Molecular Target New Drug Study, Hengyang 421001, PR China. Electronic address: hhzhou2003@163.com.
authors: Hong-Hao
authors: HH
authors: Zhou
mesh_terms: D000818:Animals; D065607:Cytochrome P-450 Enzyme Inhibitors / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007783:Lactones / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D045787:Sesquiterpenes, Eudesmane / Q000494:pharmacology*
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D007783:Lactones; D045787:Sesquiterpenes, Eudesmane; D003577:Cytochrome P-450 Enzyme System; C004363:alantolactone
keywords: Alantolactone; Alantolactone PubChem CID: 72724; CYP3A4; Drug–drug interaction; Human liver microsomes; Noncompetitive inhibition