Curcumin Reactivates Silenced Tumor Suppressor Gene RARβ by Reducing DNA Methylation

Reactivation of tumor suppressor genes by nontoxic bioactive food component represents a promising strategy for cancer chemoprevention. Retinoic acid receptor β (RARβ), one member of the RAR receptor family, is considered as a tumor suppressor. Reduced expression of RARβ has been reported in lung cancer and other solid tumors. DNA hypermethylation of the promoter region of RARβ is a major mechanism for its silencing in tumors. Recently, curcumin has been considered as a potential DNA methyltransferase inhibitor. Herein, we demonstrated that curcumin significantly elevate RARβ expression at the mRNA and protein levels in tested cancer cells. Additionally, curcumin decreased RARβ promoter methylation in lung cancer A549 and H460 cells. Mechanistic study demonstrated that curcumin was able to downregulate the mRNA levels of DNMT3b. In a lung cancer xenograft node mice model, curcumin exhibited protective effect against weight loss because of tumor burden. Tumor growth was strongly repressed by curcumin treatment. As the results from in vitro, RARβ mRNA were increased and DNMT3b mRNA were decreased by curcumin treatment compared with the mice in control group. Altogether, this study reveals a novel molecular mechanism of curcumin as a chemo‐preventive agent for lung cancer through reactivation of RARβ. Copyright © 2015 John Wiley & Sons, Ltd.     

姜黄素对七氟醚吸入后老年大鼠认知功能的影响

目的：观察姜黄素对七氟醚所致老年大鼠学习记忆力改变的影响以及对环氧合酶-2（COX-2）表达的影响。方法：将48只18月龄的SD老年大鼠,采用数字表法随机分为3组。分别为姜黄素组（孢-16）;七氟醚对照组（竹-16）;空白对照组（扎-16）。采用Morris水迷宫检测大鼠的空间学习记忆功能,以及检测COX-2、β淀粉样蛋白（β-amyloidpeptide,Aβ）以及人β-分泌酶（humanbeta-siteAPP-cleavingenzyme-1,BACE-1）的表达。结果：（1）Morris水迷宫进行定位航行实验和空间探索实验表明,七氟醚组及姜黄素组的老年SD大鼠学习记忆与空白对照组相比,平均逃避潜伏期延长,穿越平台象限的次数减少（P〈0．05）,七氟醚组较姜黄素组平均逃避潜伏期及穿越平台象限的次数显著减少（P〈0．05）;（2）大鼠海马区Aβ的表达：七氟醚组明显高于姜黄素组及空白对照组（P〈0．05）,而姜黄素组较空白对照组亦有明显差异（P〈0．05）;（3）七氟醚组、姜黄素组BACE-1的表达明显高于空白对照组（P〈0．05）;（4）七氟醚组、姜黄素组大鼠海马区COX-2的表达较空白对照组无显著差异（P〉0．05）。结论：姜黄素有助于改善高浓度七氟醚所致老年SD大鼠学习记忆力损害,其机制可能与下调BACE-1表达从而抑制高浓度七氟醚诱导A8的生成有关,但对COX-2表达无显著影响。     

2，5-二亚苄基环戊酮衍生物的合成及抑制K562细胞生长活性

目的设计合成2,5-二亚苄基环戊酮类化合物,并对其抗肿瘤活性进行初步的评价。方法以环戊酮为起始原料,通过Stork烯胺反应、Aldol缩合、Mannich反应制备目标化合物;并采用MTT法测试目标化合物对人慢性粒细胞白血病急变细胞株K562增殖的抑制活性。结果与结论共合成了15个未见文献报道的2,5-二亚苄基环戊酮Mannich碱类化合物,其结构经1H-NMR和MS确证。初步药理结果显示9个目标化合物对K562的增殖抑制作用强于姜黄素。     

Inhibitory effects of polyphenolic compounds on human arylamine N-acetyltransferase 1 and 2

Arylamine N-acetyltransferases (NAT) are important enzymes involved in the metabolic activation of aromatic and heterocyclic amines and inhibitors of NAT enzymes may be valuable as chemopreventive agents. Phytochemicals including cinnamic acid derivatives, various classes of flavonoids and coumarins were tested for the inhibitory activity on NAT1 and NAT2 from human liver and the human cholangiocarcinoma cell line: KMBC cells. Assays were performed using p-aminobenzoic acid and sulfamethazine as selective substrates for NAT1 and NAT2, respectively. NAT1 and NAT2 activities were present in liver cytosol. However, the KMBC cells showed only NAT1 activity. There was a marked difference in the ability of the test chemicals to inhibit NAT1 and NAT2. Caffeic acid, ferulic acid, gallic acid and EGCG inhibited NAT1 but not NAT2, whereas scopuletin and curcumin inhibited NAT2 but not NAT1. Quercetin, kaemferol and other flavonoids, except epicatechin and silymarin, inhibited both enzymes. The kinetics of inhibition of NAT1 by caffeic acid, EGCG and quercetin were of the non-competitive type, whereas that of NAT2 by quercetin, curcumin and kaemferol was also of the non-competitive type. The most potent inhibitor was quercetin, which has the inhibitory constants for NAT1 and NAT2 of 48.6?±?17.3 and 10.0?±?1.8?µM, respectively.     

Formulation and Evaluation of Curcumin Gel for Topical Application

The aim of the present investigation was to develop and study topical gel delivery of curcumin for its anti-inflammatory effects. Carbopol 934P (CRB) and hydroxypropylcellulose (HPC) were used for the preparation of gels. The penetration enhancing effect of menthol (0–12.5% w/w) on the percutaneous flux of curcumin through the excised rat epidermis from 2% w/w CRB and HPC gel system was investigated. All the prepared gel formulations were evaluated for various properties such as compatibility, drug content, viscosity, in vitro skin permeation, and anti-inflammatory effect. The drug and polymers compatibility was confirmed by Differential scanning calorimetry and infrared spectroscopy. The percutaneous flux and enhancement ratio of curcumin across rat epidermis was enhanced markedly by the addition of menthol to both types of gel formulations. Both types of developed topical gel formulations were free of skin irritation. In anti-inflammatory studies done by carrageenan induced rat paw oedema method in wistar albino rats, anti-inflammatory effect of CRB, HPC and standard gel formulations were significantly different from control group (P < 0.05) whereas this effect was not significantly different for CRB and HPC gels formulations to that of standard (diclofenac gel) formulation (P > 0.05). CRB gel showed better % inhibition of inflammation as compared to HPC gel.     

Inhibition of human glutathione S-transferases by curcumin and analogues

1. Glutathione S-transferases (GSTs) are important phase II drug-metabolizing enzymes that play a major role in protecting cells from the toxic insults of electrophilic compounds. Curcumin, a promising chemotherapeutic agent, inhibits human GSTA1-1, GSTM1-1, and GSTP1-1 isoenzymes.

2. In the present study, the effect of three series of curcumin analogues, 2,6-dibenzylidenecyclohexanone (A series), 2,5-dibenzylidenecyclopentanone (B series), and 1,4-pentadiene-3-one (C series) substituted analogues (n?=?34), on these three human GST isoenzymes, and on human and rat liver cytosolic GSTs, was investigated using 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate.

3. Most of the 34 curcumin analogues showed less potent inhibitory activities towards GSTA1-1, GSTM1-1, and GSTP1-1 than the parent curcumin. Compounds B14 and C10 were the most potent inhibitors of GSTA1-1 and human liver cytosolic GSTs, with IC₅₀ values of 0.2–0.6 μM. The most potent inhibitors of GSTM1-1 were C1, C3 and C10, with IC₅₀ values of 0.2–0.7 μM. Similarly, GSTP1-1 was predominantly strongly inhibited by compounds of the C series C0, C1, C2 C10 and A0, with IC₅₀ values of 0.4–4.6 μM. Compounds in the B series showed no significant inhibition of GSTP1-1.

4. Molecular Operating Environment (MOE) program-based quantitative structure–activity relationship (QSAR) analyses have also suggested the relevance of Van der Waals surface area and compound lipophilicity factors for the inhibition of GSTA1-1 and GSTM1-1 and partial charge factors for GSTP1-1. These results may be useful in the design and synthesis of curcumin analogues with either more or less potency for GST inhibition.

     

Antiangiogenic Effect of Curcumin in Pure Versus in Extract Forms

Curcumin isolated from turmeric (Curcuma longa L., Zingaberaceae) root was found to be anti-angiogenic in a human tissue-based angiogenesis assay. As a liposoluble compound, curcumin can be extracted from turmeric root with organic solvents such as ethanol or acetone. Curcumin in its pure form has poor solubility in water, potentially limiting its medicinal use for humans when it is taken orally or injected. This study attempted to investigate the possibility of improving curcumin's low solubility using an extract as a carrier. This would maintain anti-angiogenic properties with improved water-solubility. Experiments were undertaken to determine the extraction efficiency of different solvents for curcumin. Anti-angiogenic activities of curcumin in its pure form and in extracts were compared as a general trend ethanol or acetone was more efficient in extracting curcumin than their aqueous counterparts. Using 50 and 70% aqueous ethanol as well as 70% aqueous acetone yielded significantly more turmeric extracts by weight than absolute acetone, which was the lowest. Conversely, turmeric extracts extracted with 95% ethanol and absolute acetone contained significantly higher curcumin concentrations than water extract, which was the lowest. Combining the higher extract yield and highest curcumin concentrations in the extract, 95% ethanol gave the highest yield of single entity curcumin. In the angiogenesis assay, pure curcumin at the concentration of 85 μ M (in 1% ethanol v/v) in the culture medium totally suppressed angiogenic responses. In contrast, a curcumin concentration of 18.5 μ M (in the form of 100 μ g/ml turmeric extract) achieved the same total inhibition of angiogenesis in culture. This nearly 5 fold gap reflected the unaccounted involvement of other antiangiogenic compounds including curcumin derivatives, and/or enhancement of curcumin by non-antiangiogenic compounds in the extract. This finding suggests that curcumin in the form of extracts be potentially more pharmacologically active than pure curcumin. Further investigations of this hypothesis and possible interactions are warranted.     

姜黄素对大鼠调节血脂及抗氧化作用的研究

为研究姜黄素的降脂作用抗氧化作用,将高脂血症模型大鼠根据血总胆固醇水平随机分为４组：基础饲料对照组喂基础饲料＋姜黄素组喂加入姜黄素５ｇ／ｋｇ的基础饲料;高脂饲料对照组喂高脂饲料;高脂饲料＋姜黄素组喂加入姜黄素ｇ／ｋｇ的高脂饲料。再喂养４周,测定血脂及抗氧化指标。结果显示姜黄素能降低高脂模型大鼠血中总胆固醇、甘油三酯水平,提高载脂蛋白Ａ水平,并降低血及肝中过氧化脂质,直匀浆总抗氧化能力和ＳＯＤ活性、     

Rho GTP酶在姜黄素抑制人肺癌细胞增殖和转移中的作用

目的 探讨姜黄素对人肺癌细胞株(A549)增殖和转移的影响,并通过检测姜黄素对细胞内Rho GTP酶蛋白表达及细胞骨架重组的影响,揭示Rho GTP酶在姜黄素抑制肺癌转移中的作用。方法 应用MTT法观察姜黄素对A549增殖能力的影响,体外侵袭实验和迁移实验观察姜黄素对肺癌细胞转移的影响。Western blot和半定量RT-PCR法分别检测姜黄素对与细胞骨架重组相关的RhoA,Rac1,Cdc42蛋白和mRNA表达的影响。免疫荧光细胞化学法标记微丝,激光共聚焦扫描显微镜观察姜黄素对细胞骨架重组的影响。结果 姜黄素能抑制A549细胞增殖,增殖抑制率均随处理浓度增大和作用时间延长而增加。与对照组比较,2.5,5 μmol·L^-1的姜黄素处理24 h后的A549细胞增殖抑制率较低,但体外侵袭和迁移能力均显著下降(P<0.01)。姜黄素能显著下调RhoA,Rac1,Cdc42蛋白和mRNA表达(P<0.01),并能明显影响细胞内微丝骨架的结构和分布。结论 姜黄素可通过下调 Rho GTP 酶基因表达,调控肺癌细胞微丝骨架结构,进而抑制体外增殖和转移能力。     

姜黄素对肠炎大鼠肠黏膜环氧合酶-2的调控

目的: 探索姜黄素对炎症性肠病(IBD)模型大鼠肠黏膜炎症靶点环氧合酶-2(COX-2)的影响.方法: 建立以三硝基苯磺酸(TNBS)诱导的大鼠肠炎模型.模型大鼠给予含20 g/L的姜黄素饲料喂养,药物阳性对照组给予含5 g/L柳氮磺胺吡啶(SASP)和2 g/L N-乙酰半胱氨酸(NAC)的饲料喂养,模型组及阴性对照组给予普通饲料喂养.评价大鼠肠黏膜病理组织学评分.应用电泳迁移率改变分析法检测肠黏膜胞核NF-κB活性的变化.应用Western印迹分析法检测肠黏膜细胞质IκB及COX-2的变化.应用半定量RT-PCR检测COX-2 mRNA的表达.结果: 姜黄素改善IBD模型大鼠病理组织学征象.姜黄素可抑制IBD模型大鼠肠黏膜胞质IκB的降解,并抑制胞核NF-κB的激活,同时降低了COX-2的活性.结论: 姜黄素可预防和改善IBD鼠科模型中的实验性肠炎,调控COX-2的活性;COX-2可作为治疗炎症性肠病的药物靶点.姜黄素对治疗IBD有应用前景.