title: Stereoselective Regulation of P-gp Activity by Clausenamide Enantiomers in Caco-2, KB/KBv and Brain Microvessel Endothelial Cells.
abstract: The (-)- and (+)-clausenamide (CLA) enantiomers have different pharmacokinetic effects in animals, but their association with putative stereoselective regulation of P-glycoprotein (P-gp) remains unclear. Using three cells expressing P-gp-Caco-2, KBv and rat brain microvessel endothelial cells(RBMEC), this study investigated the association of CLA enantiomers with P-gp. The results showed that the rhodamine 123 (Rh123) accumulation, an indicator of P-gp activity, in Caco-2, KBv and RBMECs was increased by (-)CLA (1 or 5 μmol/L) at 8.2%-28.5%, but reduced by (+)CLA at 11.7%-25.9%, showing stereoselectivity in their regulation of P-gp activity. Following co-treatment of these cells with each CLA enantiomer and verapamil as a P-gp inhibitor, the (+)-isomer clearly antagonized the inhibitory effects of verapamil on P-gp efflux, whereas the (-)-isomer had slightly synergistic or additive effects. When higher concentrations (5 or 10 μmol/L) of CLA enantiomers were added, the stimulatory effects of the (+)-isomer were converted into inhibitory ones, leading to an enhanced intracellular uptake of Rh123 by 24.5%-58.2%; but (-)-isomer kept its inhibition to P-gp activity, causing 30.0%-63.0% increase in the Rh123 uptake. The biphasic effects of (+)CLA were confirmed by CLA uptake in the Caco-2 cells. (+)CLA at 1 μmol/L had significantly lower intracellular uptake than (-)CLA with a ratio[(-)/(+)] of 2.593, which was decreased to 2.167 and 1.893 after CLA concentrations increased to 2.5 and 5 μmol/L. Besides, in the non-induced KB cells, (+)CLA(5 μmol/L) upregulated P-gp expression at 54.5% relative to vehicle control, and decreased Rh123 accumulation by 28.2%, while (-)CLA(5 μmol/L) downregulated P-gp expression at 15.9% and increased Rh123 accumulation by 18.0%. These results suggested that (-)CLA could be a P-gp inhibitor and (+)CLA could be a modulator with concentration-dependent biphasic effects on P-gp activity, which may result in drug-drug interactions when combined with other P-gp substrate drugs.
authors: Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China; Beijing Key Laboratory of Non-Clinical Drug Metabolism and PK/PD Study, Beijing, China; Beijing Key Laboratory of New Drug Mechanisms and Pharmacological Evaluation Study, Beijing, China.
authors: Chuan-Jiang
authors: CJ
authors: Zhu
authors: Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors: Fang
authors: F
authors: Hua
authors: Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors: Xiao-Lu
authors: XL
authors: Zhu
authors: Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors: Meng
authors: M
authors: Li
authors: Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors: Hong-Xu
authors: HX
authors: Wang
authors: Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China; Beijing Key Laboratory of Active Substance Discovery and Druggability Evaluation, Beijing, China.
authors: Xiao-Ming
authors: XM
authors: Yu
authors: Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China; Beijing Key Laboratory of Non-Clinical Drug Metabolism and PK/PD Study, Beijing, China.
authors: Yan
authors: Y
authors: Li
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D001692:Biological Transport; D001921:Brain / Q000098:blood supply / Q000166:cytology; D018938:Caco-2 Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D004357:Drug Synergism; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007769:Lactams / Q000737:chemistry / Q000494:pharmacology*; D017705:Lignans / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D020112:Rhodamine 123 / Q000378:metabolism; D013237:Stereoisomerism; D014700:Verapamil / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000998:Antiviral Agents; D004365:Drugs, Chinese Herbal; D007769:Lactams; D017705:Lignans; C053048:clausenamide; D020112:Rhodamine 123; D014700:Verapamil