Inhibition of UDP‐Glucuronosyltransferase (UGT) Isoforms by Arctiin and Arctigenin

Arctiin is the major pharmacological ingredient of Fructus Arctii, and arctigenin is the metabolite of arctiin formed via the catalysis of human intestinal bacteria. The present study aims to investigate the inhibition profile of arctiin and arctigenin on important phase II drug‐metabolizing enzymes UDP‐glucuronosyltransferases (UGTs), indicating the possible herb–drug interaction. In vitro screening experiment showed that 100 μM of arctiin and arctigenin inhibited the activity of UGT1A3, 1A9, 2B7, and 2B15. Homology modeling‐based in silico docking of arctiin and arctigenin into the activity cavity of UGT2B15 showed that hydrogen bonds and hydrophobic interactions contributed to the strong binding free energy of arctiin (?8.14 kcal/mol) and arctigenin (?8.43 kcal/mol) with UGT2B15. Inhibition kinetics study showed that arctiin and arctigenin exerted competitive and noncompetitive inhibition toward UGT2B15, respectively. The inhibition kinetic parameters (K_i) were calculated to be 16.0 and 76.7 μM for the inhibition of UGT2B15 by arctiin and arctigenin, respectively. Based on the plasma concentration of arctiin and arctigenin after administration of 100 mg/kg of arctiin, the [I]/K_i values were calculated to be 0.3 and 0.007 for arctiin and arctigenin, respectively. Based on the inhibition evaluation standard ([I]/K_i < 0.1, low possibility; 0.1 < [I]/K_i < 1, medium possibility; [I]/K_i > 1, high possibility), arctiin might induce drug–drug interaction with medium possibility. Based on these results, clinical monitoring the utilization of Fructus Arctii is very important and necessary. Copyright © 2016 John Wiley & Sons, Ltd.     

牛蒡苷元氨解衍生物的合成及其抗肿瘤活性研究

目的：牛蒡苷元属于木脂素类化合物,水溶性差,故以牛蒡苷元为先导化合物进行结构修饰,改善其水溶性,进而提高生物度,方便制剂、扩大牛蒡苷元的临床应用范围。方法：采用丙胺与牛蒡苷元在室温下发生氨解反应,通过重结晶方法制备氨解衍生物。采用5种人癌细胞株对氨解衍生物进行抗肿瘤活性研究。结果：合成得到牛蒡苷元氨解衍生物,操作简单,后处理容易,收率较高,并且衍生物的溶解性高于牛蒡苷元。对牛蒡苷元与氨解衍生物进行抗肿瘤活性研究表明氨解衍生物的活性低于牛蒡苷元。结论：牛蒡苷元氨解衍生物的最佳合成条件为：牛蒡苷元与丙胺的质量体积比为1∶0.05,室温反应24 h,收率为64%。经活性研究表明牛蒡苷元的内酯环是抗肿瘤活性关键基团。     

牛蒡子亚临界萃取后药渣中总木脂素的富集工艺优选

目的: 优选经亚临界萃取后牛蒡子药渣中总木脂素的富集工艺,为该药材资料的开发与利用提供参考. 方法: 以牛蒡子油得率、药渣中总木脂素含量为指标,通过单因素试验考察牛蒡子亚临界萃取溶媒.采用醇提水沉法富集牛蒡子药渣中木脂素类成分,通过单因素试验优选工艺条件.采用HPLC测定牛蒡子苷和牛蒡子苷元的含量,流动相乙腈(A)-0.1%磷酸水溶液(B)梯度洗脱(0~5 min,30%~35%A;5~13 min,35%~45%A;13~15 min,45%~48%A;15~20 min,48%~53%A;20~29 min,53%~80%A;29~40 min,80%~100%A),检测波长280 nm. 结果: 选择丁烷为萃取溶媒脱脂.最佳富集工艺为加8倍量70%乙醇回流提取3次,每次1 h,滤液减压回收至0.5 g·mL^-1,按药渣量加12倍量水沉淀,煮沸回流60 min;总木脂素纯度>50%,转移率>80%. 结论: 醇提水沉法适用于牛蒡子中总木脂素部位的富集纯化,优选的工艺稳定可行.     

Arctigenin alleviates ER stress via activating AMPK

Aim:

To investigate the protective effects of arctigenin (ATG), a phenylpropanoid dibenzylbutyrolactone lignan from Arctium lappa L (Compositae), against ER stress in vitro and the underlying mechanisms.

Methods:

A cell-based screening assay for ER stress regulators was established. Cell viability was measured using MTT assay. PCR and Western blotting were used to analyze gene and protein expression. Silencing of the CaMKKβ, LKB1, and AMPKα1 genes was achieved by RNA interference (RNAi). An ATP bioluminescent assay kit was employed to measure the intracellular ATP levels.

Results:

ATG (2.5, 5 and 10 μmol/L) inhibited cell death and unfolded protein response (UPR) in a concentration-dependent manner in cells treated with the ER stress inducer brefeldin A (100 nmol/L). ATG (1, 5 and 10 μmol/L) significantly attenuated protein synthesis in cells through inhibiting mTOR-p70S6K signaling and eEF2 activity, which were partially reversed by silencing AMPKα1 with RNAi. ATG (1-50 μmol/L) reduced intracellular ATP level and activated AMPK through inhibiting complex I-mediated respiration. Pretreatment of cells with the AMPK inhibitor compound C (25 μmol/L) rescued the inhibitory effects of ATG on ER stress. Furthermore, ATG (2.5 and 5 μmol/L) efficiently activated AMPK and reduced the ER stress and cell death induced by palmitate (2 mmol/L) in INS-1 β cells.

Conclusion:

ATG is an effective ER stress alleviator, which protects cells against ER stress through activating AMPK, thus attenuating protein translation and reducing ER load.     

牛蒡子苷元对肝癌SMMC-7721细胞增殖、凋亡的影响及机制探讨

目的观察牛蒡子苷元（ARG）对肝癌SMMC-7721细胞增殖、凋亡的影响,并探讨其机制。方法将不同浓度的ARG作用于SMMC-7721细胞,并设不加ARG对照组。MTT法测算细胞增殖抑制率、流式细胞术检测细胞周期及凋亡率,RT-PCR法检测细胞中的Bcl-2 mRNA。结果与对照组比较,随ARG浓度增加,SMMC-7721细胞增殖率逐渐降低（P均〈0.05）,G0/G1期细胞比例显著增加（P均〈0.05）,G2、M、S期细胞比例减少（P均〈0.05）;随ARG浓度增加、作用时间延长,SMMC-7721细胞凋亡率显著增加（P均〈0.05）,Bcl-2 mRNA表达量减少（P均〈0.05）。结论 ARG可明显抑制SMMC-7721细胞增殖并诱导其凋亡;可能与ARG下调细胞中Bcl-2基因的表达有关。     

牛蒡子现代炮制工艺研究

目的:探讨牛蒡子的现代炮制方法。方法:选择微波强度和加热时间2个因素,按L9(34)正交来安排试验,以牛蒡子苷和牛蒡子苷元含量之和为考察指标。结果:最佳工艺为微波强度中火,加热3min。结论:微波加热的方法简便、可行,可作为牛蒡子的现代炮制工艺。     

牛蒡子苷元诱导人白血病细胞凋亡的作用及机制

牛蒡子来源于菊科两年生草本植物牛蒡子属牛蒡(Aictium lappa L.)的干燥成熟果实,为常用中药.有疏风散热、解毒透疹、利咽消肿等功效,现代药理学研究表明牛蒡子有抗病毒[1,5]、抗炎[2]、抗癌[3,4]、抑制热休克反应[6]等广泛的药理活性.其主要活性成分是牛蒡子苷元(arctigenin,ARG)[1].     

牛蒡子中牛蒡苷和牛蒡苷元的测定

目的：测定牛蒡子中牛蒡苷和牛蒡苷元的含量。方法采用 Agilent-C18（4.6mm ×250mm,5μm）色谱柱;流动相：甲醇-水二元梯度洗脱,流速0.8mL· min －1,检测波长280nm。结果牛蒡苷和牛蒡苷元分别在0.36～2.8μg（r＝0.9995）,0.006～0.56μg（r＝0.9996）范围内线性关系良好。平均回收率牛蒡苷为100.3％,RSD为2.3％;牛蒡苷元为99.5％,RSD为2.9％。结论该方法简便、准确,实验结果可为牛蒡子的质量控制提供参考。     

牛蒡子苷元对结肠癌细胞增殖的影响及相关机制研究

目的：探讨牛蒡子苷元对结肠癌细胞系SW480增殖的影响及相关机制。方法：以结肠癌细胞系SW480为研究对象,通过MTT比色法检测牛蒡子苷元对SW480细胞生长速度和倍增时间的影响;通过软琼脂克隆形成实验观察牛蒡子苷元对SW480细胞软琼脂集落形成率的影响;应用RT—PCR技术探讨牛蒡子苷元对SW480细胞增殖的相关机制。结果：①不同浓度牛蒡子苷元处理的SW480细胞生长速度明显减慢,倍增时间显著延长,并且呈现一定的浓度和时间依赖性;②SW480亲本细胞和牛蒡子苷元（20mg／L）处理24h的SW480细胞的克隆形成率分别为24．933％和4．533％（P〈0．01）,与SW480亲本细胞相比,牛蒡子苷元（20mg／L）处理24小时的SW480细胞形成的克隆体积较小;（3）与SW480亲本细胞相比,20mg／L牛蒡子苷元处理的SW480细胞中,cyclinA基因表达没有明显变化,p21基因表达上调,而cyclinB、cyclinE基因表达下调。结论：①牛蒡子苷元可抑制SW480细胞的增殖能力。②诱导p21基因表达上调,cyclinB和cyclinE基因表达下调是牛蒡子苷元抑制SW480细胞增殖的可能机制。