Activating Effect of Effective Components in Medicinal and Edible Substances on Human Pregnane X Receptor and Cytotoxicity Screening / 中国实验方剂学杂志

ObjectiveTo explore the activating effects of ten important effective components in seven medicinal and edible substances on human pregnane X receptor （PXR）， including Glycyrrhizae Radix et Rhizoma （liquiritin and glycyrrhizic acid）， Houttuyniae Herba （quercetin and houttuyfonate）， Prunellae Spica （rosmarinic acid）， Cassiae Semen （aurantio-obtusin）， Poria （pachymic acid）， Lilii Bulbus （Lilium brownii saponin and colchicine）， and Lycii Fructus （Lycium barbarum polysaccharide） and screen potentially toxic components. MethodCell counting kit-8 （CCK-8） assay was used to investigate the cytotoxic effect of liquiritin， glycyrrhizic acid， quercetin， houttuyfonate， rosmarinic acid， pachymic acid， aurantio-obtusin， and colchicine （10， 20， and 50 μmol·L-1）， and L. brownii saponin and L. barbarum polysaccharide （10， 20， and 50 mg·L-1） on normal human hepatocyte cell line （L02）. The release of lactate dehydrogenase （LDH） in L02 cells after drug treatments was detected by the biochemical analyzer. The apoptosis induced by ten effective components was explored by Hoechst 33342 staining. The secreted luciferase reporter system was used to co-transfect the PXR expression vector and reporter gene vector containing cytochrome P450 3A4 （CYP3A4） transcriptional regulatory region into L02 cells， with 10 μmol·L-1 rifampicin （RIF） as a positive control. After treated with liquiritin， glycyrrhizic acid， quercetin， houttuyfonate， rosmarinic acid， aurantio-obtusin， pachymic acid， and colchicine （5， 10， and 20 μmol·L-1） and L. brownii saponin and L. barbarum polysaccharide （5， 10， and 20 mg·L-1） for 24 h， the cells were tested for secreted luciferase activity. ResultCompared with the control group， colchicine， L. brownii saponin， and quercetin decreased the cell viability （P<0.05， P<0.01）. Compared with the control group， quercetin， rosmarinic acid， glycyrrhizic acid， colchicine， aurantio-obtusin， and pachymic acid increased the release rate of LDH in L02 cells （P<0.05， P<0.01）. The proportion of hyperchromatic nuclei increased gradually after rosmarinic acid， liquiritin， and L. barbarum polysaccharide treatments as compared with the control group （P<0.05， P<0.01）. In terms of co-transfection of pcDNA3.1-PXR and pGLuc-CYP3A4 into L02 cells， compared with the control group， aurantio-obtusin and pachymic acid showed activating effects on PXR （P<0.05）， whereas liquiritin and glycyrrhizic acid showed inhibitory effects （P<0.05）. ConclusionThe findings suggest that when medicinal and edible substances are taken for a long time， attention should be paid to their influence on drug-metabolizing enzymes and possible interactions， so as to improve their safety.

Effect of six components in Polygoni Multiflori Radix on regulation of CYP3A4 mediated by human pregnane X receptor / 中国中药杂志

This paper aimed to study the six chemical components of Polygoni Multiflori Radix (gallic acid, quercetin, luteolin, kaempferol, resveratrol, apigenin). By the established pregnane X receptor (human pregnant X receptor, PXR) CYP3A4 mediated drug induced rapid screening technique, the effect of chemical components on the cell activity was detected by MTS cell method, and the value of IC₅₀ was calculated. The dual luciferase reporter system was used to co-transfect PXR reporter gene expression vector containing transcriptional regulation and CYP3A4 with HepG2 cells, with 10 μmol·L⁻¹ rifampicin (RIF) as a positive control, and 10 μmol·L⁻¹ of ketoconazole (TKZ) as negative control. Gallic acid, quercetin, luteolin, kaempferol, apigenin, resveratrol(5, 10, 20 μmol·L⁻¹) were used to incubate for 24 h, and the luciferase activity was detected. The results showed that when plasmid pcDNA3.1 was co-transfected with pGL4.17-CYP3A4, gallic acid and resveratrol had an inhibitory effect on the regulation of CYP3A4, and quercetin, luteolin, kaempferol had an inductive effect on CYP3A4; when pcDNA3.14-PXR was co-transfected with pGL4.17-CYP3A4, quercetin, luteolin, kaempferol, apigenin, resveratrol had an inductive effect. To sum up, the 6 reported liver injury components had inhibitory or activating effects on CYP3A4. After PXR plasmid was involved, 5 components had an inductive effect on CYP3A4, and the inductive effects of 2 components were significantly different. In this experiment, we found that 2 kinds of potential liver injury components in Polygoni Multiflori Radix had been induced by CYP3A4, which was achieved through PXR regulation. It suggested that attention shall be paid to potential drug interactions when combined with Polygoni Multiflori Radix, so as to improve the safety and efficacy.

In silico investigation of agonist activity of a structurally diverse set of drugs to hPXR using HM-BSM and HM-PNN / 华中科技大学学报（医学）（英德文版）

The human pregnane X receptor (hPXR) plays a critical role in the metabolism, transport and clearance of xenobiotics in the liver and intestine. The hPXR can be activated by a structurally diverse of drugs to initiate clinically relevant drug-drug interactions. In this article, in silico investigation was performed on a structurally diverse set of drugs to identify critical structural features greatly related to their agonist activity towards hPXR. Heuristic method (HM)-Best Subset Modeling (BSM) and HM-Polynomial Neural Networks (PNN) were utilized to develop the linear and non-linear quantitative structure-activity relationship models. The applicability domain (AD) of the models was assessed by Williams plot. Statistically reliable models with good predictive power and explain were achieved (for HM-BSM, r (2)=0.881, q LOO (2) =0.797, q EXT (2) =0.674; for HM-PNN, r (2)=0.882, q LOO (2) =0.856, q EXT (2) =0.655). The developed models indicated that molecular aromatic and electric property, molecular weight and complexity may govern agonist activity of a structurally diverse set of drugs to hPXR.

Establishment of hPXR mediated reporter gene model for UGT1A1 and its application / 中国药学杂志

OBJECTIVE: To develop hPXR mediated reporter gene model for UGT1A1, and use it as an in vitro model for determination of induction activity toward UGT1A1 of various commonly used traditional Chinese medicines (TCMs) extracts. METHODS: The distal and proximal promoters of UGT1A1 were amplified from human genetic DNA, and were cloned into pGL3 vector as pGL3-PXRE plasmid, which was then cotransfected into HepG2 cells with hPXR expression plasmid to establish the reporter gene model. Then the model was applied to determine the induction activity toward UGT1 A1 of various commonly used TCMs extracts. RESULTS: The promoters of UGT1A1 were successfully cloned into pGL3 vector to form pGL3-PXRE recombinant plasmid, and the reporter gene model was successfully established. Nine kinds of TCMs extracts were investigated, and three were found to activate hPXR and therefore have the potential to induce UGT1A1. CONCLUSION: The model established is an effective method for determination of activators of hPXR and potential inducers of UGT1A1 in vitro. Copyright 2012 by the Chinese Pharmaceutical Association.