title: Inhibitory effects of herbal constituents on P-glycoprotein in vitro and in vivo: herb-drug interactions mediated via P-gp.
abstract: Modulation of drug transporters via herbal medicines which have been widely used in combination with conventional prescription drugs may result in herb-drug interactions in clinical practice. The present study was designed to investigate the inhibitory effects of 50 major herbal constituents on P-glycoprotein (P-gp) in vitro and in vivo as well as related inhibitory mechanisms. Among these herbal medicines, four constituents, including emodin, 18β-glycyrrhetic acid (18β-GA), dehydroandrographolide (DAG), and 20(S)-ginsenoside F₁ [20(S)-GF₁] exhibited significant inhibition (>50%) on P-gp in MDR1-MDCKII and Caco-2 cells. Emodin was the strongest inhibitor of P-gp (IC₅₀=9.42 μM), followed by 18β-GA (IC₅₀=21.78 μM), 20(S)-GF₁ (IC₅₀=76.08 μM) and DAG (IC₅₀=77.80 μM). P-gp ATPase activity, which was used to evaluate the affinity of substrates to P-gp, was stimulated by emodin and DAG with Km and Vmax values of 48.61, 29.09 μM and 71.29, 38.45 nmol/min/mg protein, respectively. However, 18β-GA and 20(S)-GF₁ exhibited significant inhibition on both basal and verapamil-stimulated P-gp ATPase activities at high concentration. Molecular docking analysis (CDOCKER) further elucidated the mechanism for structure-inhibition relationships of herbal constituents with P-gp. When digoxin was co-administered to male SD rats with emodin or 18β-GA, the AUC(₀₋t) and Cmax of digoxin were increased by approximately 51% and 58%, respectively. Furthermore, 18β-GA, DAG, 20(S)-GF₁ and Rh₁ at 10 μM significantly inhibited CYP3A4/5 activity, while emodin activated the metabolism of midazolam in human liver microsomes. In conclusion, four herbal constituents demonstrated inhibition of P-gp to specific extents in vitro and in vivo. Taken together, our findings provided the basis for the reliable assessment of the potential risks of herb-drug interactions in humans.
authors.affiliation: Department of Drug Metabolism, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. Electronic address: lixue@imm.ac.cn.
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Drug Metabolism, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. Electronic address: hujp@imm.ac.cn.
authors.forename: Jinping
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Drug Metabolism, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. Electronic address: wangbaolian@imm.ac.cn.
authors.forename: Baolian
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Drug Metabolism, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. Electronic address: shengli@imm.ac.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Sheng
authors.affiliation: Department of Drug Metabolism, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. Electronic address: liuzhihao@imm.ac.cn.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Drug Metabolism, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. Electronic address: yangsh@imm.ac.cn.
authors.forename: Shuang
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Drug Metabolism, State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China. Electronic address: yanli@imm.ac.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D019540:Area Under Curve; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism; D004077:Digoxin / Q000008:administration & dosage; D004224:Diterpenes / Q000009:adverse effects*; D004642:Emodin / Q000009:adverse effects*; D036145:Ginsenosides / Q000009:adverse effects*; D006034:Glycyrrhetinic Acid / Q000009:adverse effects / Q000031:analogs & derivatives*; D041743:Herb-Drug Interactions; D006801:Humans; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000473:pathology; D011487:Protein Conformation; D051381:Rats; D014700:Verapamil / Q000008:administration & dosage
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D004224:Diterpenes; D036145:Ginsenosides; C119129:18alpha-glycyrrhetinic acid; C055327:ginsenoside F1; D004077:Digoxin; D014700:Verapamil; C510164:CYP3A5 protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D004642:Emodin; D006034:Glycyrrhetinic Acid; C478098:dehydroandrographolide
keywords: ATPase activity; Herb–drug interactions; Inhibition; MDR1-MDCKII cells; Molecular docking; P-glycoprotein