ABSTRACT
@#To investigate the influential mechanism of total flavonoids from Abelmoschus Manihot (HKZ) on cytochrome P450 (CYP450) isoforms in human liver microsomes and to verify its effect on the most significantly inhibited subtype CYP2C9 in rats.The inhibitory effects of HKZ on human CYP3A4, CYP2C9, CYP2C19, CYP2E1, CYP1A2 and CYP2D6 were evaluated through the cocktail method using ultra-performance liquid chromatography tandem mass spectrometry, then its inhibitory mechanism was investigated and kinetic parameters of enzyme inhibition were calculated By comparing the pharmacokinetic behaviors of tolbutamide after single or multiple administration of 200 mg/kg HKZ and equal dose of CMC-Na in rats, the effects of HKZ on CYP2C11 enzyme (CYP2C9 isoenzyme) was estimated.The results indicated the significant inhibitory effect of HKZ on CYP2C9 and CYP2E1 with IC50 of 3.22 and 8.64 μg/mL, respectively. Also, it showed certain inhibitory ability on other isoforms with IC50 of 20-30 μg/mL.As demonstrated, HKZ may not be a time-dependent inhibitor which competitively inhibited CYP2E1 and CYP2C9 with Ki of 3.84 and 6.33 μg/mL.In contrast, it showed noncompetitive inhibition on CYP3A4 mediated testosterone-6β-hydroxylation and midazolam-4-hydroxylation reaction with Ki of 7.37 and 3.32 μg/mL.It was also a noncompetitive inhibitor of CYP1A2, CYP2D6 and CYPC219 with Ki values of 8.66, 11.49 and 21.94 μg/mL. HKZ did not change the pharmacokinetic parameters of CYP2C11 probe substrate tolbutamide in rat, but it affected the AUC0-t, cmax of 4-hydroxytolubutamide (P < 0.05). Therefore, drug-drug interaction mediated by CYP450 should be considered in clinical study.
ABSTRACT
Acetaminophen (APAP, also known as paracetamol)-induced liver injury is the leading cause of drug-induced liver injury in the world. Wuzhi Tablet (WZ, an ethanol extract of Schisandra sphenanthera) is widely used in clinical practice to protect liver function. Our previous studies have shown that pretreatment with WZ for 3 days can significantly protect against APAP-induced liver injury; however, the effect of different intervals between APAP and WZ treatment on APAP-induced liver injury remains unclear. In this study, the change in liver injury indexes, APAP metabolites, and the activity of cytochrome P450 (CYP450) enzymes after treatment with WZ and APAP at different intervals were determined. The animal experiment was reviewed and approved by the Animal Ethics Committee of Sun Yat-sen University. The results show that 0 h, 0.5 h, and 2 h pretreatment with WZ significantly protected against APAP-induced liver injury in mice, as evidenced by a significant decrease in biochemical parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), and malonaldehyde (MDA). WZ inhibited the metabolic activation of APAP mediated by CYP450 enzymes and reduced the formation of APAP metabolites. This study further demonstrates that pretreatment with WZ at different intervals (0 h, 0.5 h, and 2 h before APAP dosing) exerts a significant hepatoprotective effect against APAP-induced liver injury, and a single-dose of WZ inhibits the activity of CYP450 enzymes related to APAP metabolic activation, thereby protecting against APAP-induced hepatotoxicity.
ABSTRACT
Objective: To investigate the protective effects of matrine combined with glycyrrhizic acid on chronic liver injury induced by carbon tetrachloride, and explore the protective mechanism from the points of energy metabolism and CYP enzyme.Methods: The chronic hepatic injury model of rats was induced by CCl4.The changes of activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum were measured to observe the protective effect of the two drugs and their combination.The contents of glutamate dehydrogenase (GLDH) in serum and adenine nucleoside three phosphate (ATP), adenosine diphosphate (ADP) and adenine monophosphate (AMP) in liver tissue were determined to evaluate the regulation effect on hepatic energy metabolism and mitochondrial function.The levels of CYP1A2, CYP2E1 mRNA and protein in liver tissue were detected by real-time PCR and Western Blot to evaluate the two drugs and their combination on the regulation function of liver CYP enzyme.Results: Matrine (72.8 mg×kg-1)and glycyrrhizic acid(43.4 mg·kg-1)could decrease the serum activities of ALT and ALT in chronic hepatic injury model, and the combination (matrine 36.4 mg·kg-1+glycyrrhizic acid 21.7 mg·kg-1) had the most significant protective effect (P＜0.05).Matrine (72.8 mg·kg-1)and glycyrrhizic acid(43.4 mg·kg-1)could decrease GLDH in serum,and restore the content of ATP in liver (P＜0.05).Matrine (72.8 mg·kg-1) had no effect on the expression of CYP1A2 and CYP2E1mRNA, and glycyrrhizin (43.4 mg·kg-1) could inhibit the expression of CYP1A2, CYP2E1mRNA and protein (P＜0.05).Conclusion: Matrine combined with glycyrrhizin has obvious regulation effect on mitochondrial function and liver protective effect in chronic hepatic injury model.
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OBJECTIVE: To identify the specific cytochrome P450 (CYP) enzymes involved in the metabolism of dipfluzine hydrochloride (Dip) in the rat liver microsomes. METHODS: The rat liver microsomes were prepared and incubated with Dip. The Dip metabolites (M1, M2, M4 and M5) were identified by LC-MS/MS, and the CYP isoenzymes were identified by the combination of the selective CYP inhibitor study, correlation analysis and a panel of recombinant rat CYP expereiment, respectively. RESULTS: The results from the experiments of selective CYP inhibitors, correlation analysis and recombinant rat CYP isoenzymes indicated that CYP2A1, CYP3A and CYP2C11 contributed to the formation of M1 and M5 in the rat liver microsomes. CYP3A, CYP2A1, CYP1A2, CYP2C11 and CYP2E1 metabolized Dip to M2. CYP3A, CYP2A1, CYP2E1 and CYP2C11 contributed to M4 formation. And the recombinant rat CYP researches further indicated that CYP3A2 exhibited more activity than CYP3A1. CONCLUSION: CYP3A and CYP2A1 are the major CYP isoenzymes responsible for catalyzing Dip to the four metabolites formation in the rat liver microsomes.
ABSTRACT
Aim To evaluate the inhibitive and induc-tive effects of Polygonum capitatum water extract on main cytochrome P450 isoforms in human and liver mi-crosomes of mouse in vitro for predicting the herb-drug interactions in clinical application. Methods The in vitro inhibitory effect was evaluated by incubating Po-lygonum capitatum water extract with the probe sub-strates of main phase I metabolic enzymes in human liver microsomes, including CYP1A2, CYP2E1, CYP2C9,CYP2C19 and CYP3A4. Mice were adminis-tered with Polygonum capitatum water extract at dosage of 0 . 58 g · kg-1 and 1 . 16 g · kg-1 by gastric lavage for successive 7 days and 14 days, then the cocktail-LC-MS/MS method was applied to assess the inductive effect of main CYP450 isoforms in mouse liver micro-somes. Results The IC50 values of Polygonum capita-tum water extract on main CYP450 isoforms in human liver microsomes were from 849 . 6 mg · L-1 to 2 287 mg·L-1 . Compared with the blank control group, the activites of CYP2C9 and CYP3A4 in 1. 16 g·kg-1 7 d group were about 49 . 9 % and 21. 1 % higher ( P <0. 01, P < 0. 05 ) respectively, the activities of CYP2C9 and CYP3A4 in 0. 58 g·kg-1 7 d group were 27. 6 % and 15. 5 % higher ( P <0. 01 , P <0. 05 ) respectively, the activities of CYP2C9 and CYP3A4 in 1. 16 g·kg-1 14 d group were 67. 5 % and 32. 1 %higher (P<0. 01) respectively, while the activities of CYP1 A2 , CYP2 E1 and CYP2 C19 were not increased significantly in Polygonum capitatum treatment group. Conclusions Polygonum capitatum water extract do not show the inhibitory effect on main CYP450 in hu-man liver microsomes. There is induction on CYP2C9 and CYP3 A4 in mouse liver microsomes by Polygonum capitatum water extract.