In vitro ex vivo assessment of Morinda citrifolia on drug metabolizing enzymes in spontaneously hypertensive rats

Morinda citrifolia Linn. (Rubiaceae), common name noni, has been used as a herbal medicine for over 2000 years. The consumption of noni, and especially the fruit, stresses the importance, urgency, and possibility of the examination of drug interaction when concomitantly administered with a drug. The objectives of this study were to determine the effects of noni juice (NJ) on aminopyrine N-demethylase (APND), uridine diphosphoglucuronosyl-transferase (UGT), and cytosolic glutathione S-transferase (GST) drug metabolizing enzymes and the molecular mechanism elucidation of NJ on APND using different inhibitors and stimulators. The in vitro results for APND showed that different concentrations of NJ significantly increased the activity in isolated hepatocytes at 1.0?ng/mL, 10?ng/mL, 10?μg/mL, 20?μg/mL, 50?μg/mL, and 100?μg/mL. The ex vivo results demonstrated that NJ (210?mg/kg) produced a statistically significant increase in APND activity following 1 day of NJ treatment. The results for UGT and GST showed a decrease in the activity of UGT at a dose of 21?mg/kg following 1 day of treatment, and at 2.1 and 21?mg/kg following 14 days of treatment. GST enzyme demonstrated an increase in activity by 100% for all doses following 1 day of treatment. Molecular mechanism elucidation of the ex vivo effect of NJ on phase I APND showed that KT5720 significantly reduced the activity as compared to control. A change in activity of APND, UGT, and GST following 1 day and 14 days of treatment suggests that all three metabolic pathways may play a role in herb–drug interaction by modulation of metabolic enzymes.     

Multiple variants in UGT1A1 gene are factors to develop indirect hyper-bilirubinemia

Most Taiwanese patients with hyper-bilirubinemia have genetic abnormalities in the uridine diphosphoglucuronate-glucuronosyltransferase 1A1 (UGT1A1) gene beyond the variants in the TATA box upstream of UGT1A1 associated with Gilbert’s syndrome. To investigate the role of UGT1A1 in the pathogenesis of indirect hyper-bilirubinemia, we prospectively studied 97 consecutive patients with indirect hyper-bilirubinemia for genotypes of promoter [(TA)₆TAA6, (TA)₇TAA7] and coding region [nucleotide (nt)-211, nt-686, nt-1,091 and nt-1,456] of UGT1A1. Thirty-six of the patients (45.6%) were found to have Gilbert’s syndrome with 7/7 genotype; among them, 14 also carried variants at nt-686. Forty-two patients (43.3%) had the 6/7 genotype; among them, 36 patients were found to have one or more variants in the coding region. Patients with higher serum total bilirubin are associated with higher likelihood of carrying Gilbert’s syndrome genotype: 60.0% (P=0.007) patients with serum total bilirubin level ≥2.5 mg/dL carried the Gilbert’s syndrome genotype, while only 23.9% of patients with serum total bilirubin level <2.5 mg/dL carry the same genotype (P=0.0006). Forty-one of the 61 non-Gilbert’s patients had one homogenous variants or two or more heterozygous variants in UGT1A1. Further studies are necessary to confirm the role of one homo-zygous variant or two or more hetero-zygous variants in UGT1A1 gene as factors for indirect hyper-bilirubinemia.     

Characterization of in vitro metabolites of cudratricusxanthone A in human liver microsomes

Cudratricusxanthone A (CTXA), isolated from the roots of Cudrania tricuspidata, exhibits several biological activities; however, metabolic biotransformation was not investigated. Therefore, metabolites of CTXA were investigated and the major metabolic enzymes engaged in human liver microsomes (HLMs) were characterized using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). CTXA was incubated with HLMs or human recombinant CYPs and UGTs, and analysed by an LC‐MS/MS equipped electrospray ionization (ESI) to qualify and quantify its metabolites. In total, eight metabolites were identified: M1–M4 were identified as mono‐hydroxylated metabolites during Phase I, and M5–M8 were identified as O‐glucuronidated metabolites during Phase II in HLMs. Moreover, these metabolite structures and a metabolic pathway were identified by elucidation of MSⁿ fragments and formation by human recombinant enzymes. M1 was formed by CYP2D6, and M2–M4 were generated by CYP1A2 and CYP3A4. M5–M8 were mainly formed by UGT1A1, respectively. While investigating the biotransformation of CTXA, eight metabolites of CTXA were identified by CYPs and UGTs; these data will be valuable for understanding the in vivo metabolism of CTXA. Copyright © 2015 John Wiley & Sons, Ltd.     

广西三江县侗族新生儿UGT1A1基因变异分析北大核心CSCD

目的探讨广西柳州三江县侗族新生儿UGT1A1基因变异特点及其与侗族新生儿高胆红素血症发生的关系。方法前瞻性选取2021年1月至2022年1月于三江县人民医院新生儿科诊断不明原因高胆红素血症的新生儿84例为研究对象;另选取同期健康新生儿60例纳入健康对照组。提取两组新生儿外周血基因组DNA,对UGT1A1启动子区TATA盒和外显子1进行PCR扩增并进行基因测序。结果病例组检测出33例G71R错义突变,突变率为39%,A等位基因频率(21%)显著高于健康对照组(10%)(P<0.05)。携带G71R错义突变基因型的侗族新生儿发生高胆红素血症的风险是携带野生型的健康新生儿的2.588倍(P<0.05)。Hardy-Weinberg遗传平衡检验结果提示两组新生儿UGT1A1 G71R位点基因型符合遗传平衡(P>0.05)。结论UGT1A1 G71R突变是三江县侗族新生儿高频基因变异类型,且G71R错义突变与侗族新生儿发生高胆红素血症相关。     

Association of UGT1A6 gene polymorphism with clinical outcome in pediatric epileptic patients on sodium valproate monotherapy

Pediatric epilepsy comprises chronic neurological disorders characterized by recurrent seizures. Sodium valproate is one of the common antiseizure medications used for treatment. Glucuronide conjugation is the major metabolic pathway of sodium valproate, carried out by the enzyme uridine 5′-diphosphate (UDP) glucuronosyl transferase (UGT) whose gene polymorphisms may alter the clinical outcome. The objective of this study was to assess the association between UGT1A6 genetic polymorphism and clinical outcome in terms of efficacy and tolerability in pediatric epileptic patients on sodium valproate monotherapy. Pediatric epileptic patients (n=65) aged 2-18 years receiving sodium valproate monotherapy for the past one month were included. Genetic polymorphism patterns of UGT1A6 (T19G, A541G, A552C) were evaluated by PCR-RFLP. Clinical outcome was seizure control during the 6 months observation period. Tolerability was measured by estimating the hepatic, renal, and other lab parameters. Out of 65 patients, TT (40%), TG (57%), and GG (3%) patterns were observed in UGT1A6 (T19G) gene, AA (51%), AG (40%), and GG (9%) in (A541G) gene, and AA (43%), AC (43%), and CC (14%) in (A552C) gene. No statistical difference in clinical outcome was found for different UGT1A6 genetic polymorphism patterns. We concluded that different patterns of UGT1A6 genetic polymorphism were not associated with the clinical outcome of sodium valproate in terms of efficacy and tolerability. Sodium valproate was well-tolerated among pediatric patients with epilepsy and can be used as an effective antiseizure medication.     

未结合型高胆红素血症患者UGT1A1基因的突变分析

目的 分析未结合型高胆红素血症患者尿苷二磷酸葡糖醛酸基转移酶1A1(uridine diphosphate glucuronosyltransferase 1A1,UGT1A1)基因的突变情况,并探讨突变与血清总胆红素的关系.方法 抽提患者外周血基因组DNA,扩增UGT1A1基因的编码序列及启动子区,对扩增产物进行测序以确定基因突变.结果 在61例未结合型高胆红素血症患者中,共发现46例存在UGT1A1基因的突变.突变可分为5种,依据频率高低依次为211G→A、TATAA盒TA插入、686C→A、1091C→T以及1352C→T.携带单一位点纯合突变合并其它位点杂合突变患者的血清胆红素水平明显高于单位点纯合突变或多位点杂合突变患者(P＜0.05).综合UGT1A1基因突变与血清总胆红素水平,44例未结合型高胆红素血症患者被诊断为Gilbert综合征,2例被诊断为Ⅱ型Crigler-Najjar综合征.结论 患者血清总胆红素水平不仅与UGT1A1基因突变数量有关,而且与突变的杂合或纯合状态有关.     

Molecular characterization of UDP-glucuronosyltransferases 3A and 8A in cynomolgus macaques

UDP-glucuronosyltransferases (UGTs) are drug-metabolizing enzymes essential for the metabolism of endogenous substrates and xenobiotics. The cynomolgus macaque is a nonhuman primate species widely used in drug metabolism studies. The molecular characteristics of UGTs have been extensively investigated in humans, but they remain to be elucidated in cynomolgus macaques. In this study, cynomolgus macaque UGT3A1, UGT3A2, and UGT8A1 cDNAs were isolated and characterized. Amino acid sequences deduced from cynomolgus UGT3A1, UGT3A2, and UGT8A1 cDNAs were highly identical with their human orthologs (93, 96, and 99%, respectively) and were closely clustered in a phylogenetic tree. In the genome, cynomolgus UGT3A and UGT8A genes were located in the regions corresponding to those of their human orthologs. Among the 10 tissue types analyzed, expression of cynomolgus UGT3A1 and UGT3A2 mRNAs was detected in liver, kidney, and testis; the UGT3A1 and UGT3A2 mRNAs were most abundant in liver and testis, respectively. Cynomolgus UGT8A1 was most abundantly expressed in kidney, followed by brain, jejunum, and testis. These results suggest that cynomolgus UGT3As and UGT8A1 have molecular similarities to their human orthologs.     

Analysis of the Complicated Nonlinear Pharmacokinetics of Orally Administered Telmisartan in Rats Using a Stable Isotope-IV Method

This study aimed to kinetically analyze the nonlinear absorption and systemic exposure of telmisartan (TEL) after oral administration to rats by using a stable isotope-IV method. Rats were orally administered different dose of TEL, followed by the intravenous injection of 0.005 mg/kg of deuterium-labeled TEL (TEL-d3). Assuming that TEL-d3 shows same pharmacokinetic properties with TEL, systemic clearance (CL_tot), oral bioavailability (F_oral), and intestinal and hepatic availability (F_a*F_g, F_h) of TEL were calculated in each individual rat. AUC_po of TEL increased disproportionately with dose and showed a sigmoid-type relation, indicating the involvement of multi-nonlinear processes in oral absorption of TEL. F_a*F_g of TEL increased with dose at the low-dose range while decreased at the high-dose range. In contrast, F_h increased and CL_tot decreased significantly in the middle range (2 to 6 mg/kg). As main factors of nonlinearity, saturations of solubility, efflux transport in the intestine, and the hepatic uptake of TEL were indicated. In conclusion, this study demonstrated a high possibility of a stable isotope-IV method to characterize complicated pharmacokinetic properties of oral drugs in animals, which can help to consider the future risks in their clinical use.     

Phase II study of pharmacogenetic-tailored therapy in elderly colorectal cancer patients

Background

Retrospective analyses suggested that a pharmacogenetic approach may allow a tailored selection of chemotherapy for metastatic colorectal cancer.

Aim

We conducted a phase II study of pharmacogenetic-selected first-line chemotherapy in elderly patients with advanced colorectal cancer, with the aim to improve efficacy and to reduce toxicity in this group of patients.

Methods

24 patients were enrolled in this study. Chemotherapy regimen was prospectively assigned based on TS, DPD, ERCC-1 and UGT1A1 genotyping results. Twelve patients (50%) were treated with modified FOLFIRI, 11 patients (46%) with modified FOLFOX6 and 1 (4%) with De Gramont regimen.

Results

A partial remission was obtained in 4 cases (17%), stable disease in 8 cases (33%) and progressive disease in 12 cases (50%). Grade 3-4 neutropenia was observed in 7 patients (29%) and diarrhoea in 3 cases (12%). The trial was then interrupted according to study design requiring 13 partial remissions out of the first 24 patients enrolled as the necessary response rate level in order to continue.

Conclusion

Prospective selection of chemotherapy based on TS, DPD, ERCC-1 and UGT1A1 expression in elderly advanced colorectal cancer patients failed to confirm previous results. A more accurate validation of retrospective findings is warranted before these molecular markers can be used for treatment selection in the clinical practice.