Mangifera indica L. Extract and Mangiferin Modulate Cytochrome P450 and UDP‐Glucuronosyltransferase Enzymes in Primary Cultures of Human Hepatocytes

The aqueous stem bark extract of Mangifera indica L. (MSBE) has been reported to have antioxidant, anti‐inflammatory and analgesic properties. In previous studies, we showed that MSBE and mangiferin, its main component, lower the activity of some cytochrome P‐450 (P450) enzymes in rat hepatocytes and human liver microsomes. In the present study, the effects of MSBE and mangiferin on several P450 enzymes and UDP‐glucuronosyltransferases (UGTs) in human‐cultured hepatocytes have been examined. After hepatocytes underwent a 48‐h treatment with sub‐cytotoxic concentrations of the products (50–250 µg/mL), a concentration‐dependent decrease of the activity of the five P450 enzymes measured (CYP1A2, 2A6, 2C9, 2D6 and 3A4) was observed. For all the activities, a reduction of at least 50% at the highest concentration (250 µg/mL) was observed. In addition, UGT activities diminished. MSBE considerably reduced UGT1A9 activity (about 60% at 250 µg/mL) and lesser effects on the other UGTs. In contrast, 250 µg/mL mangiferin had greater effects on UGT1A1 and 2B7 than on UGT1A9 (about 55% vs. 35% reduction, respectively). Quantification of specific mRNAs revealed reduced CYP3A4 and 3A5 mRNAs content, and an increase in CYP1A1, CYP1A2, UGT1A1 and UGT1A9 mRNAs. No remarkable effects on the CYP2A6, 2B6, 2C9, 2C19, 2D6 and 2E1 levels were observed. Our results suggest that the activity and/or expression of major P450 and UGT enzymes is modulated by MSBE and that potential herb–drugs interactions could arise after a combined intake of this extract with conventional medicines. Therefore, the potential safety risks of this natural product derived by altering the ADMET properties of co‐administered drugs should be examined. Copyright © 2012 John Wiley & Sons, Ltd.     

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??OBJECTIVE To compare the effect on CYP450 isoenzyme in rats with acute liver injury induced by different chemicals.METHODS Acute liver injury model of rats induced by tetrachloromethane(CCl₄), D-aminogalactose(D-GalN)/lipopolysaccharide(LPS), ??-naphthyl isothiocyanate(ANIT) respectively whereas the normal Wistar rats were used as controls. After the tail vein injection with Cocktail probe solutions prepared with five CYP450s probe substrates (phenacetin-CYP1A2, omeprazole-CYP2C9, tolbutamide-CYP2C19, dextromethorphan-CYP2D6, midazolam-CYP3A4), the blood samples were collected from the fundus venous plexus of rat at different time point, the blood drug concentration of the five probe substrates were determined by LC-MS/MS, and the pharmacokinetic parameters were calculated by PK Solutions 2^TM. Compared with normal rats, the changes of the probe drug pharmacokinetics in different rat models were used as the basis for the evaluation of the metabolic activity of CYP450 isoenzyme.RESULTS Compared with normal rats, the activities of CYP1A2, CYP2C9, CYP2C19, CYP2D6 of CCl₄ group rats were significantly inhibited,and the activities of CYP3A4 was slightly inhibited; the activities of CYP2C9, CYP2D6 and CYP3A4 of D-GalN/LPS group rats were significantly induced, and the activity of CYP2D6 and CYP3A4 was slightly induced, and the activity of CYP1A2 was not significantly affected, but the activity of CYP2C19 was significantly inhibited; the activities of CYP2C9, CYP2C19 and CYP3A4 of ANIT group rats were significantly induced, the activity of CYP3A4 were slightly induced,and the activity of CYP2D6 was not significantly affected, but the activity of CYP1A2 was significantly inhibited.CONCLUSION There are significant differences in the activities of CYP450 isoenzyme in the rat model of acute liver injury induced by different chemicals.     

Marsdenia tenacissima extract inhibits gefitinib metabolism in vitro by interfering with human hepatic CYP3A4 and CYP2D6 enzymes

Ethnopharmacological relevance

The stem of Marsdenia tenacissima (Roxb.) Wight et Arn. is mainly produced in Yunnan China and has long been used as a medicine to treat cancer in China. Xiao-Ai-Ping injection, the water-soluble part of the stem of Marsdenia tenacissima, is administrated as an anti-cancer agent in clinics for decades. Our previous study showed that Marsdenia tenacissima extract (MTE) restored gefitinib sensitivity in gefitinib-resistant non-small cell lung cancer (NSCLC) cells, but the mechanism involved is unknown. Gefitinib undergoes hepatic metabolism predominantly through human cytochrome P450 (CYP) 3A4 and CYP2D6 enzymes. This study aims to evaluate whether MTE interferes with gefitinib metabolism via human hepatic P450 enzymes.

Material and methods

A cocktail-substrate assay was used to test the effect of MTE on major CYP enzyme activities by incubation of pooled human liver microsomes with specific substrate probes of CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in the absence and presence of MTE. Recombinant human CYP450 enzymes were used to predict in vitro gefitinib metabolic clearance in the absence and presence of MTE. The metabolites of the substrate probes and gefitinib were detected by high-performance liquid chromatographic tandem mass spectrometry (HPLC-MS/MS). Human hepatoma HepG2 cells were used to investigate the effect of gefitinib alone or in combination with MTE on CYP3A4 and CYP2D6 mRNA and protein expression.

Results

The cocktail-substrate assay showed that MTE inhibited CYP450 activities in human liver microsomes with the inhibition rate of 3A4>2C9>2C19>1A2>2D6. The co-administration of MTE with gefitinib significantly decreased the in vitro intrinsic clearance (Cl_int) of gefitinib by 2.6 and 4.0-fold for CYP2D6 and CYP3A4, respectively, but did not affect other CYP450s. CYP2D6 and CYP3A4 mRNA and protein expression in human hepatoma HepG2 cells were greatly reduced in the combined gefitinib and MTE treatment.

Conclusion

We demonstrate that MTE inhibits gefitinib metabolism by interfering with CYP3A4 and CYP2D6. Meanwhile, MTE combined with gefitinib down-regulates the mRNA and protein expression of CYP3A4 and CYP2D6 in the HepG2 cells. Thus, these data suggest that MTE is a promising herbal medicine to enhance gefitinib efficacy through improving its metabolic stability.     

半夏泻心汤及不同配伍组对大鼠肝脏 CYP450酶活性的影响

目的:研究半夏泻心汤及不同配伍组对大鼠肝微粒体CYP450亚型酶的影响,从肝脏代谢角度评价半夏泻心汤组方的合理性。方法:将大鼠随机分为全方组、辛开组、苦降组、甘补组及空白对照组,分别灌胃水煎液,运用肝微粒体体外温孵法,对探针底物进行孵育,并结合超高效液相检测方法,测定各探针底物代谢产物的含量,计算代谢速率,以反映各给药组的肝微粒体CYP2C6,CYP2E1,CYP3A1/2亚型酶活性。结果:与空白组相比,全方组,苦降组对各亚型酶均起抑制作用(P<0.01);辛开组对CYP2C6有抑制作用(P<0.01),而对CYP2E1和CYP3A1/2无显著抑制作用;甘补组对CYP2C6和CYP2E1亚型起抑制作用(P<0.01),而对CYP3A1/2无抑制作用。结论:全方对大鼠肝微粒体CYP450酶起抑制作用,比较各配伍组间差异,苦降组抑制作用较其他配伍组显著。     

清开灵注射液及其主要成分黄芩苷和栀子苷对人肝微粒体CYP450酶6种亚型的体外抑制作用研究

 目的 研究清开灵注射液及其主要成分黄芩苷和栀子苷对人肝微粒体CYP1A2、CYP2C8、CYP2C9、CYP2C19、CYP2D6和CYP3A4的体外抑制作用。方法 采用液相色谱-串联质谱法（LC-MS/MS）同时测定对乙酰氨基酚、6α-羟基紫杉醇、4-羟基双氯芬酸、4-羟基美芬妥英、右啡烷、1-羟基咪达唑仑和6β-羟基睾酮,分别代表CYP1A2、CYP2C8、CYP2C9、CYP2C19、CYP2D6和CYP3A4的活性;清开灵注射液、黄芩苷、栀子苷和7种混合探针底物在人肝微粒体中共同孵育,并计算其IC₅₀值表示对CYP450酶的抑制程度。结果 在人肝微粒体体外孵育体系中,清开灵注射液对CYP1A2的IC₅₀值为0.6%,对其他亚型的IC₅₀值从1.1%到6.0%;黄芩苷和栀子苷对CYP450酶6种亚型的IC₅₀值均大于100 μmol·L-1。结论 在正常剂量下,清开灵注射液对人肝微粒体CYP1A2可能有抑制作用,对人肝微粒体CYP2C8、CYP2C9、CYP2C19、CYP2D6和CYP3A4无明显抑制作用;黄芩苷和栀子苷对CYP450酶6种亚型均无抑制作用。     

扶正化瘀方对正常及肝纤维化大鼠体内CYP450酶的影响

使用Cocktail探针药物法,研究扶正化瘀方(FZHY)对正常和肝纤维化大鼠细胞色素P450(CYP450)5种同工酶的影响。正常和二甲基亚硝胺(dimethylnitrosamine,DMN)腹腔注射诱导的肝纤维化模型大鼠,以FZHY浸膏粉连续灌胃2周后,单剂量尾静脉注射由CYP450 5种同工酶的特异性探针底物非那西丁(CYP1A2)、甲苯磺丁脲(CYP2C9)、奥美拉唑(CYP2C19)、氢溴酸右美沙芬(CYP2D6)和咪达唑仑(CYP3A4)配置的Cocktail探针溶液后,通过建立的LC-MS/MS法同时检测血浆中5种探针药物的浓度,采用PK solution 2TM对数据进行处理,并计算主要药动学参数。正常大鼠灌胃FZHY后,非那西丁、甲苯磺丁脲、奥美拉唑和氢溴酸右美沙芬的AUC0-t均出现不同程度的增加,CL也均出现降低趋势,提示FZHY能明显抑制正常大鼠CYP1A2,CYP2C9,CYP2C19,CYP2D6的活性,但对CYP3A4的活性影响不明显;肝纤维化大鼠灌胃FZHY后,甲苯磺丁脲的AUC0-t显著增加,Vd显著降低,其他4种探针药物的药动学参数未见显著改变,提示在肝纤维化大鼠体内FZHY仅对CYP2C9有抑制作用,对CYP1A2,CYP2C19,CYP2D6,CYP3A4活性影响不明显。CYP450酶在肝纤维化条件下活性的改变可能是FZHY对正常和肝纤维化大鼠CYP450酶影响不同的原因。     

疏血通注射液对大鼠细胞色素P450酶6种亚型活性的影响

目的用Cocktail探针药物法,研究疏血通注射液对大鼠细胞色素P450酶(CYP450)6种亚型活性的影响。方法将Wistar雄性大鼠随机分组,实验组给予疏血通注射液,空白组给予生理盐水,诱导7 d,分别以咖啡因、甲苯磺丁脲、奥美拉唑、美托洛尔、氯唑沙宗、氨苯砜作为CYP1A2、CYP2C9、CYP2C19、CYP2D6、CYP2E1、CYP3A1/2的探针药物。HPLC法检测探针药物的血药浓度,DAS软件估算药动学参数。结果与空白组相比,咖啡因和氨苯砜的t1/2、AUC0-t、AUC0-∞均显著增大,CL/F显著降低(P<0.05);氯唑沙宗的AUC0-t、AUC0-∞显著降低,CL/F显著增大(P<0.05);而甲苯磺丁脲、奥美拉唑、美托洛尔的药代动力学参数无显著性差异。结论疏血通注射液对大鼠CYP1A2、CYP3A1/2亚型的活性有抑制作用,能诱导CYP2E1亚型的活性,而对CYP2C9、CYP2C19和CYP2D6亚型的活性无显著影响。     

In vitro inhibition of Huanglian [Rhizoma coptidis (L.)] and its six active alkaloids on six cytochrome P450 isoforms in human liver microsomes

Huanglian (Rhizoma Coptidis) as a popular herb has been used for the treatment of various diseases such as diarrhea, eye inflammation and women's abdominal ailments. Alkaloids are considered to be responsible for its pharmacological effects. In this investigation, Huanglian and its six alkaloids (coptisine, epiberberine, berberine, jateorrhizine, palmatine and magnoflorine) were systematically evaluated for their inhibition of six cytochrome P450 isoforms (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) in human liver microsomes by the LC‐MS/MS method. Huanglian showed the strongest inhibition of CYP2D6, followed by CYP1A2 and CYP3A4_T. The IC₅₀ values were 5.8 µg/mL, 36.8 µg/mL and 59.2 µg/mL, respectively. Of the constituents tested, coptisine and epiberberine showed strong inhibition of CYP2D6 with IC₅₀ values of 4.4 µm and 7.7 µm ; berberine, jateorrhizine and palmatine showed weak inhibition of CYP2D6 with IC₅₀ values of 45.5 µm , 49.4 µm and 92.6 µm , respectively; jateorrhizine showed moderate inhibition of CYP3A4_T with an IC₅₀ value of 13.3 µm ; coptisine showed weak inhibition of CYP1A2 with an IC₅₀ value of 37.3 µm . In addition, activation was observed in coptisine/CYP2C9 and palmatine/CYP2C9/CYP2C19. Other CYP450 isoforms were not affected markedly by the six alkaloids. In conclusion, Huanglian showed in vitro inhibition of CYP2D6, the inhibition might be contributed mostly by protoberberine alkaloids, especially coptisine and epiberberine. Herb–drug interactions may occur through the CYP2D6 inhibition. Copyright © 2011 John Wiley & Sons, Ltd.     

Differential inhibition of rat and human hepatic cytochrome P450 by Andrographis paniculata extract and andrographolide

The inhibitory effect of Andrographis paniculata extract (APE) and andrographolide (AND), the most medicinally active phytochemical in the extract, on hepatic cytochrome P450s (CYPs) activities was examined using rat and human liver microsomes. For this purpose, CYP1A2-dependent ethoxyresorufin-O-deethylation, CYP2B1-dependent benzyloxyresorufin-O-dealkylation, CYP2B6-dependent bupropion hydroxylation, CYP2C-dependent tolbutamide hydroxylation, CYP2E1-dependent p-nitrophenol hydroxylation and CYP3A-dependent testosterone 6 beta-hydroxylation activities, were determined in the presence and absence of APE or AND (0-200 microM). APE inhibited ethoxyresorufin-O-deethylation activity in rat and human liver microsomes, with apparent Ki values of 8.85 and 24.46 microM, respectively. In each case, the mode of inhibition was noncompetitive. APE also inhibited tolbutamide hydroxylation both in rat and human microsomes with apparent Ki values of 8.21 and 7.51 microM, respectively and the mode of inhibition was mixed type. In addition, APE showed a competitive inhibition only on CYP3A4 in human microsomes with Ki of 25.43 microM. AND was found to be a weak inhibitor of rat CYP2E1 with a Ki of 61.1 microM but did not affect human CYP2E1. In conclusion, it cannot be excluded from the present study that APE could cause drug-drug interactions in humans through CYP3A and 2C9 inhibition.     

Reversible inhibition of three important human liver cytochrome p450 enzymes by tiliroside

Tiliroside, an active flavonoid extensively found in many medicinal plants including Helichrysum italicum, Geranium mexicanum and Helianthemum glomeratum, has been demonstrated to exert multiple biological effects including antiinflammatory, antimicrobial, antioxidant and antitumor activities. Cytochrome P450 (CYP) enzymes play an important role in the Phase I oxidation metabolism of a wide range of xenobiotics and inhibition of CYP isoforms might influence the elimination of drugs and induce serious adverse drug response. The inhibition of seven CYP isoforms (CYP3A4, CYP1A2, CYP2A6, CYP2D6, CYP2C9, CYP2C8 and CYP2E1) by tiliroside was investigated using in vitro human liver microsomal incubation assays. The results showed that tiliroside strongly inhibited the activity of CYP3A4 (IC(50) = 9.0 ± 1.7 μm), CYP2C8 (IC(50) = 12.1 ± 0.9 μm) and CYP2C9 (IC(50) = 10.2 ± 0.9 μm) with other CYP isoforms negligibly influenced. Further kinetic analysis showed that inhibition of these three CYP isoforms by tiliroside is best fit to a competitive way. The K(i) value was calculated to be 5.5 μm, 3.3 μm, 9.4 μm for CYP3A4, CYP2C9 and CYP2C8, respectively. The relatively low K(i) values suggested that tiliroside might induce drug-drug interactions with many clinically used drugs which are mainly metabolized by these three CYP isoforms. Therefore, attention should be given to the probable drug-drug interaction between tiliroside-containing herbs and substrates of CYP3A4, CYP2C9 and CYP2C8.     

血府逐瘀汤对大鼠肝组织内CYPs, UGTs和GSTs基因表达的影响

目的: 研究血府逐瘀汤对大鼠肝组织内药物代谢酶细胞色素P450（CYPs, cytochrome P450）,谷胱甘肽-S-转移酶GSTs,glutathione S transferase）和尿甘二磷酸葡糖醛酸转移酶（UGTs,UDP-glucuronosyl transferase）基因表达的影响。 方法: 将25只大鼠随机分为5组,每组5只。大鼠按3.51,7.02,14.04 g·kg^-1分别ig给予血府逐瘀汤水提物,空白组给等体积纯净水,连续给药15 d,苯巴比妥钠于第13天按80 mg·kg^-1腹腔注射,连续3 d。取200 mg左右肝脏,用逆转录-实时荧光定量PCR法检测肝组织内的CYP基因CYP1A1,CYP1A2,CYP2B1,CYP2C11,CYP2E1,CYP3A1,CYP3A2,CYP4A1,CYP7A1,CYP17A1,CYP27A1,GST基因GSTA2,GSTM1,GSTp1和UGT基因UGT1A1,UGT2B1的表达情况。 结果: 与空白组比较,苯巴比妥钠组（阳性组）可明显诱导CYP2B1,CYP3A1,CYP3A2,GSTA2和UGT2B1基因表达（84.57,5.44,5.11,7.76,13.27倍,P<0.01）;血府逐瘀汤3.51,7.02 g·kg^-1分别诱导GSTA2和CYP1A1的基因表达（1.54倍,P<0.05;57.92倍,P<0.05）;14.04 g·kg^-1明显抑制CYP2C11的基因表达（55%,P<0.05）;3.51,7.02,14.04 g·kg^-13个剂量对GSTM1有明显的抑制作用（53%,55%,51%,P<0.05）;血府逐瘀汤对CYP1A2,CYP2B1,CYP2E1,CYP3A1,CYP3A2,CYP4A1,CYP7A1,CYP17A1,CYP27A1,GSTp1,UGT1A1和UGT2B1的基因表达无明显影响。 结论: 血府逐瘀汤可明显诱导CYP1A1,GSTA2基因的表达,对CYP2C11,GSTM1的基因有明显的抑制作用,而对其余的亚型无显著影响。提示临床上与CYP1A1及CYP2C11的底物合用时,要注意药物代谢性相互作用,且其可能参与肝脏对毒物、致癌物以及其他物质的解毒和排泄,对多种恶性肿瘤的发生可能起到一定的作用。     

Inhibition of human P450 enzymes by natural extracts used in traditional medicine

Different medicinal plants are widely used in Cuba and Mexico to treat several disorders. This paper reports in vitro inhibitory effects on the P450 system of herbal products commonly used by people in Cuba and Mexico in traditional medicine for decades. Experiments were conducted in human liver microsomes. The catalytic activities of CYP1A1/2, 2D6, and 3A4 were measured using specific probe substrates. The Heliopsis longipes extract exhibited a concentration-dependent inhibition of the three enzymes, and similar effects were produced by affinin (an alkamide isolated from the H. longipes extract) and two catalytically reduced alkamides. Mangifera indica L. and Thalassia testudinum extracts, two natural polyphenol-rich extracts, diminished CYP1A1/2 and 3A4 activities, but not the CYP2D6 activity. These results suggest that these herbs inhibit the major human P450 enzymes involved in drug metabolism and could induce potential herbal-drug interactions.     

Inhibition of UDP‐Glucuronosyltransferases (UGTs) Activity by constituents of Schisandra chinensis

Structure–activity relationship for the inhibition of Schisandra chinensis's ingredients toward (Uridine‐Diphosphate) UDP‐glucuronosyltransferases (UGTs) activity was performed in the present study. In vitro incubation system was employed to screen the inhibition capability of S. chinensis's ingredients, and in silico molecular docking method was carried out to explain possible mechanisms. At 100 μM of compounds, the activity of UGTs was inhibited by less than 90% by schisandrol A, schisandrol B, schisandrin, schisandrin C, schisantherin A, gomisin D, and gomisin G. Schisandrin A exerted strong inhibition toward UGT1A1 and UGT1A3, with the residual activity to be 7.9% and 0% of control activity. Schisanhenol exhibited strong inhibition toward UGT2B7, with the residual activity to be 7.9% of control activity. Gomisin J of 100 μM inhibited 91.8% and 93.1% of activity of UGT1A1 and UGT1A9, respectively. Molecular docking prediction indicated different hydrogen bonds interaction resulted in the different inhibition potential induced by subtle structure alteration among schisandrin A, schisandrin, and schisandrin C toward UGT1A1 and UGT1A3: schisandrin A > schisandrin > schisandrin C. The detailed inhibition kinetic evaluation showed the strong inhibition of gomisin J toward UGT1A9 with the inhibition kinetic parameter (K_i) to be 0.7 μM. Based on the concentrations of gomisin J in the plasma of the rats given with S. chinensis, high herb–drug interaction existed between S. chinensis and drugs mainly undergoing UGT1A9‐mediated metabolism. In conclusion, in silico‐in vitro method was used to give the inhibition information and possible inhibition mechanism for S. chinensis's components toward UGTs, which guide the clinical application of S. chinensis. Copyright © 2015 John Wiley & Sons, Ltd.     

Strong Specific Inhibition of UDP‐glucuronosyltransferase 2B7 by Atractylenolide I and III

Drug‐metabolizing enzymes inhibition‐based drug–drug interaction remains to be the key limiting factor for the research and development of efficient herbal components to become clinical drugs. The present study aims to determine the inhibition of uridine 5′‐diphospho‐glucuronosyltransferases (UGTs) isoforms by two important efficient herbal ingredients isolated from Atractylodes macrocephala Koidz, atractylenolide I and III. In vitro recombinant UGTs‐catalysed glucuronidation of 4‐methylumbelliferone was used to determine the inhibition capability and kinetics of atractylenolide I and III towards UGT2B7, and in silico docking method was employed to explain the possible mechanism. Atractylenolide I and III exhibited specific inhibition towards UGT2B7, with negligible influence towards other UGT isoforms. Atractylenolide I exerted stronger inhibition potential than atractylenolide III towards UGT2B7, which is attributed to the different hydrogen bonds and hydrophobic interactions. Inhibition kinetic analysis was performed for the inhibition of atractylenolide I towards UGT2B7. Inhibition kinetic determination showed that atractylenolide I competitively inhibited UGT2B7, and inhibition kinetic parameter (Ki) was calculated to be 6.4 μM. In combination of the maximum plasma concentration of atractylenolide I after oral administration of 50 mg/kg atractylenolide I, the area under the plasma concentration‐time curve ration AUC_i/AUC was calculated to be 1.17, indicating the highly possible drug–drug interaction between atractylenolide I and drugs mainly undergoing UGT2B7‐catalysed metabolism. Copyright © 2015 John Wiley & Sons, Ltd.     

黄芪甲苷对大鼠肝微粒体酶活性影响

目的:研究黄芪甲苷对CYP450酶的影响,为制定合理用药方案提供科学依据。方法:以甲苯磺丁脲、氯唑沙宗、香豆素、硝苯地平、非那西丁为探针药,HPLC测定探针药与相应代谢产物的浓度,在体外的孵育体系中研究黄芪甲苷对CPY2C9,CPY2E1,CPY2A6,CPY3A4和CPY1A2酶活性的影响。结果:黄芪甲苷对CYP1A2,CYP2A6,CYP2E1酶的活性没有明显的影响,而对CYP2C9和CYP3A4酶的IC50分别为35.40,88.22μmol.L-1。结论:黄芪甲苷对CYP2C9和CYP3A4酶有明显的抑制作用,在与经由CYP2C9,CYP3A4酶代谢的药物合用时,可能会产生药物相互作用。     

Fennel and Raspberry Leaf as Possible Inhibitors of Acetaminophen Oxidation

In addition to CYP2E1, several CYP isoenzymes, notably CYP1A2, 2D6, and 3A4, are suggested to contribute in acetaminophen oxidation and formation of the hepatotoxic metabolite N‐acetyl‐p‐benzoquinone imine (NAPQI). The in vitro CYP2E1 inhibitory potentials of fennel and raspberry leaf, herbs previously found to inhibit CYP1A2, 2D6, and 3A4 activities in vitro, were investigated. Extracts from commercially available herbal products were incubated with recombinant cDNA‐expressed human CYP2E1. A validated LC/MS/MS methodology was applied for determination of 6‐hydroxychlorzoxazone formation with disulfiram used as a positive inhibitory control. CYP2E1 IC₅₀ inhibition constants were found to be 23 ± 4 and 27 ± 5 µg/ml for fennel and raspberry leaf, respectively, constants significantly lower than those presented in the literature for other herbal extracts. Together with previous findings, the presented in vitro data for CYP2E1 inhibition suggest that fennel and raspberry leaf have a significant potential of inhibiting all the major metabolic pathways for acetaminophen oxidation and NAPQI formation. Both herbs should be further investigated for their in vivo ability of inhibiting acetaminophen oxidation and NAPQI formation. Copyright © 2014 John Wiley & Sons, Ltd.     

Evaluation of Inhibitory Effects of Caffeic acid and Quercetin on Human Liver Cytochrome P450 Activities

When herbal drugs and conventional allopathic drugs are used together, they can interact in our body which can lead to the potential for herb–drug interactions. This work was conducted to evaluate the herb–drug interaction potential of caffeic acid and quercetin mediated by cytochrome P450 (CYP) inhibition. Human liver microsomes (HLMs) were added to each selective probe substrates of cytochrome P450 enzymes with or without of caffeic acid and quercetin. IC₅₀, Ki values, and the types of inhibition were determined. Both caffeic acid and quercetin were potent competitive inhibitors of CYP1A2 (Ki = 1.16 and 0.93 μM, respectively) and CYP2C9 (Ki = 0.95 and 1.67 μM, respectively). Caffeic acid was a potent competitive inhibitor of CYP2D6 (Ki = 1.10 μM) and a weak inhibitor of CYP2C19 and CYP3A4 (IC₅₀ > 100 μM). Quercetin was a potent competitive inhibitor of CYP 2C19 and CYP3A4 (Ki = 1.74 and 4.12 μM, respectively) and a moderate competitive inhibitor of CYP2D6 (Ki = 18.72 μM). These findings might be helpful for safe and effective use of polyphenols in clinical practice. Our data indicated that it is necessary to study the in vivo interactions between drugs and pharmaceuticals with dietary polyphenols. Copyright © 2014 John Wiley & Sons, Ltd.     

决明子水提液对大鼠肝脏CYP450酶的影响

该文研究决明子水提液对大鼠肝脏CYP450酶酶活性、mRNA及蛋白表达水平的影响。取SD大鼠,口服灌胃受试药物后,处死,用冰冷生理盐水灌流肝脏,提取大鼠肝脏微粒体、肝脏总RNA和总蛋白,采用Cocktail体外孵育法结合液质联用(LCMS)技术对大鼠肝脏中CYP1A2,2B1,2C11,2D2,2E1,3A1各亚酶的酶活性进行测定,并应用荧光定量PCR技术和Western blot对上述亚型的mRNA和蛋白表达水平进行检测。结果表明,酶活性方面,决明子水提液组与空白组比较可明显诱导CYP1A2,2B1,2C11,2D2,2E1,3A1的酶活性,其中决明子低剂量组对CYP2D2有明显的抑制作用,中、高剂量组对CYP2D2有明显的诱导作用,且都呈剂量依赖性增加,但对CYP3A1的诱导不呈剂量依赖性;mRNA表达方面,决明子水提液对CYP1A2,2C11,2D2,2E1mRNA的表达具有显著诱导作用,其中对CYP1A2,2D2,2E1诱导作用呈剂量依赖性,与酶活性水平具有一致性,对CYP2B1,3A1没有明显作用;蛋白表达方面,决明子水提液对CYP2C11,2E1的表达也具有诱导作用,但没有统计学差异。决明子水提液对CYP450同工酶不同程度诱导或抑制作用,特别是对于CYP2C11,2E1亚型酶,酶活性与mRNA,蛋白表达水平具有一致性,提示当与这些酶底物合并用药时,尤其是与CYP2C11,2E1代谢有关的药物合用时,应充分考虑到潜在的有益和不利的药物相互作用。     

The effects of commercial preparations of herbal supplements commonly used by women on the biotransformation of fluorogenic substrates by human cytochromes P450

The study set out to determine the potential for commercially available preparations of black cohosh (Actaea racemosa), chaste tree berry (Vitex agnus‐castus), crampbark (Viburnum opulus) and false unicorn (Chamaelirium luteum) to inhibit the major human drug metabolizing enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 as well as CYP1A1 which activates some carcinogens. In vitro microplate‐based assays using cDNA‐expressed CYP450 isoforms and fluorogenic substrates were used. Components of the commercial herbal preparations interfered with the assays and limited the concentration ranges that could be tested. Nevertheless, the fluorogenic assays were robust, reproducible and easy to perform and thus are still useful for initial screening for potential herb – drug interactions. None of the preparations affected CYPs 1A1 or 2C9 at the concentrations tested but all preparations inhibited some of the enzymes with potencies around 1 μg/mL. The three most potent interactions were: chaste tree berry and CYP2C19 (IC₅₀ 0.22 μg/mL,); chaste tree berry and CYP3A4 (IC₅₀ 0.3 μg/mL); black cohosh and CYP2C19 (IC₅₀ 0.37 μg/mL,). Thus, the study successfully identified the potential for the commercial herbal preparations to inhibit human drug metabolizing enzymes. Whether this potential translates into clinically significant herb – drug interactions can only be confirmed by appropriate in vivo studies. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of Vernonia cinerea Compounds on Drug‐metabolizing Cytochrome P450s in Human Liver Microsomes

Vernonia cinerea has been widely used in traditional medicines for various diseases and shown to aid in smoking abstinence and has anticancer properties. V. cinerea bioactive compounds, including flavonoids and hirsutinolide‐type sesquiterpene lactones, have shown an inhibition effect on the nicotine‐metabolizing cytochrome P450 2A6 (CYP2A6) enzyme and hirsutinolides reported suppressing cancer growth. In this study, V. cinerea ethanol extract and its bioactive compounds, including four flavonoids and four hirsutinolides, were investigated for an inhibitory effect on human liver microsomal CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 using cocktail inhibition assays combined with LC‐MS/MS analysis. Among tested flavonoids, chrysoeriol was more potent in inhibition on CYP2A6 and CYP1A2 than other liver CYPs, with better binding efficiency toward CYP2A6 than CYP1A2 (K_i values in competitive mode of 1.93 ± 0.05 versus 3.39 ± 0.21 μM, respectively). Hirsutinolides were prominent inhibitors of CYP2A6 and CYP2D6, with IC₅₀ values of 12–23 and 15–41 μM, respectively. These hirsutinolides demonstrated time‐dependent inhibition, an indication of mechanism‐based inactivation, toward CYP2A6. Quantitative prediction of microsomal metabolism of these flavonoids and hirsutinolides, including half‐lives and hepatic clearance rate, was examined. These findings may have implications for further in vivo studies of V. cinerea. Copyright © 2017 John Wiley & Sons, Ltd.