Effect of diallyl trisulfide-rich garlic oil on blood coagulation and plasma activity of anticoagulation factors in rats.

Diallyl trisulfide (DAT)-rich garlic oil was fed to Sprague-Dawley rats and the effects of this DAT-rich garlic oil on bleeding time, clotting time and anticoagulation factors were examined. Garlic oil supplement at 5 or 50mg garlic oil/kg bodyweight significantly prolonged bleeding time and thrombin time, and enhanced anticoagulation factor activity, such as antithrombin III and protein C (P<0.05). These results suggested that the anticoagulant action of DAT-rich garlic oil was due to inhibition and/or inactivation of thrombin. In addition, DAT-rich garlic oil benefits blood anticoagulation factors, which might further prevent the development of thrombus formation. However, the intake of garlic oil at high dose significantly increased plasma fibrinogen concentration (P<0.05), and affected the levels of several hematological parameters such as erythrocyte count, hemoglobin and platelets (P<0.05). The adverse effect of high doses of garlic oil might further influence the hemostatic balance. Therefore, the concentration of DAT-rich garlic oil should be carefully considered in its application. Supplementation of garlic oil at 5mg/kg bodyweight has anticoagulation effect in this animal study.     

Bcl-XL siRNA对人胃腺癌MGC-803细胞药物敏感性的影响

目的:研究靶向Bcl-XL基因的小干扰RNA对胃腺癌MGC-803细胞Bcl-XL基因表达的作用及对药物敏感性的影响。方法:构建的Bcl-XLsiRNA载体或阴性siRNA并稳定转染到胃癌MGC-803细胞,G418抗生素筛选阳性克隆,克隆扩大培养,免疫荧光观察细胞蛋白表达。用不同浓度的5-FU或DADS处理稳定转染细胞,MTT观察细胞增殖的变化。用一种浓度的5-FU或DADS处理稳定转染细胞,流式细胞术观察亚G1细胞的比例。结果:免疫荧光结果表明,Bcl-XLsiRNA稳定转染组细胞中Bcl-XL蛋白的表达比阴性siRNA稳定转染组细胞Bcl-XL基因的表达均有明显的降低。当不同浓度的5-FU(13、130、1 300、13 000 mg.L-1)或DADS(20、35、50mg.L-1)处理细胞24 h后,MTT结果表明Bcl-XLsiR-NA细胞组A570吸光度值较阴性siRNA细胞组和未转染对照明显降低,细胞生长抑制率明显增高。5-FU或DADS药物的IC50值在Bcl-XLsiRNA细胞组有明显降低。使用5-FU(130 mg.L-1)或DADS(50mg.L-1)处理细胞24 h后,流式结果表明,Bcl-XL-siRNA细胞组较阴性siRNA和正常对照细胞组亚G1细胞比例有明显增高。结论:Bcl-XL siRNA下调了MGC-803细胞Bcl-XL基因的表达;Bcl-XLsiRNA能够促进MGC-803细胞凋亡,增强细胞对化疗药物的敏感性。     

Detection of exhaled hydrogen sulphide gas in rats exposed to intravenous sodium sulphide

Background and purpose:

Sodium sulphide (Na₂S) disassociates to sodium (Na⁺) hydrosulphide, anion (HS⁻) and hydrogen sulphide (H₂S) in aqueous solutions. Here we have established and characterized a method to detect H₂S gas in the exhaled breath of rats.

Experimental approach:

Male rats were anaesthetized with ketamine and xylazine, instrumented with intravenous (i.v.) jugular vein catheters, and a tube inserted into the trachea was connected to a pneumotach connected to a H₂S gas detector. Sodium sulphide, cysteine or the natural polysulphide compound diallyl disulphide were infused intravenously while the airway was monitored for exhaled H₂S real time.

Key results:

Exhaled sulphide concentration was calculated to be in the range of 0.4–11 ppm in response to i.v. infusion rates ranging between 0.3 and 1.1 mg·kg⁻¹·min⁻¹. When nitric oxide synthesis was inhibited with N^ω-nitro-L-arginine methyl ester the amount of H₂S exhaled during i.v. infusions of sodium sulphide was significantly increased compared with that obtained with the vehicle control. An increase in circulating nitric oxide using DETA NONOate [3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene] did not alter the levels of exhaled H₂S during an i.v. infusion of sodium sulphide. An i.v. bolus of L-cysteine, 1 g·kg⁻¹, and an i.v. infusion of the garlic derived natural compound diallyl disulphide, 1.8 mg·kg⁻¹·min⁻¹, also caused exhalation of H₂S gas.

Conclusions and implications:

This method has shown that significant amounts of H₂S are exhaled in rats during sodium sulphide infusions, and the amount exhaled can be modulated by various pharmacological interventions.     

Diallyl disulfide induces apoptosis in human colon cancer cell line (COLO 205) through the induction of reactive oxygen species,endoplasmic reticulum stress,caspases casade and mitochondrial-dependent pathways

In this study, we investigated the effects of DADS on human colon cancer cell line COLO 205 on cell cycle arrest and apoptosis in vitro. After 24 h treatment of COLO 205 cells with DADS, the dose- and time-dependent decreases of viable cells were observed and the IC₅₀ was 22.47 μM. The decreased percentages of viable cells are associated with the production of ROS. Treatment of COLO 205 cells with DADS resulted in G2/M phase arrest and apoptosis occurrence through the mitochondrial-pathway (Bcl-2, Bcl-xL down-regulation and Bak, Bax up-regulation). DADS increased cyclin B, cdc25c-ser-216-9 and Wee1 but did not affect CDK1 protein and gene expression within 24 h of treatment. DADS-induced apoptosis was examined and confirmed by DAPI staining and DNA fragmentation assay. DADS promoted caspase-3, -8 and -9 activity and induced apoptosis were accompanied by increasing the levels of Fas, phospho-Ask1 and -JNK, p53 and decreasing the mitochondrial membrane potential which then led to release the cytochrome c, cleavage of pro-caspase-9 and -3. The COLO 205 cells were pre-treated with JNK inhibitor before leading to decrease the percentage of apoptosis which was induced by DADS. Inhibition of caspase-3 activation blocked DADS-induced apoptosis on COLO 205 cells.     

二烯丙基二硫对白血病细胞株增殖的影响

 目的探讨二烯丙基二硫(DADS)对HL-60白血病细胞株的作用.方法采用MTT法观察DADS对体外培养的HL-60细胞的生长抑制;应用酶联免疫吸附剂测定(ELISA)法检测药物作用前后白血病HL-60细胞培养上清液中VEGF蛋白的含量.结果DADS对HL-60细胞具有明显的生长抑制效应,其对HL-60细胞的生长抑制率与药物浓度、时间有明显依赖关系,DADS(作用细胞72 h)浓度从0.625μg/ml增至20.0μg/ml,其对HL-60细胞的生长抑制率由16.7%增至71%,各实验组随时间增加抑制率明显增加(P＜0.01);HL-60细胞中均有VEGF蛋白的分泌,与空白对照组相比DADS 3个浓度组(0.625,1.25,2.5 μg/ml)作用HL-60细胞72 h均能下调VEGF蛋白的分泌(P＜0.01).结论DADS能明显抑制HL-60细胞的增殖;DADS可能通过抑制HL-60细胞VEGF的分泌发挥抗白血病的效应.     

DADS诱导人白血病细胞HL-60凋亡的流式细胞术检测

目的 运用流式细胞术检测二烯丙基二硫(diallyl disulfide, DADS)诱导人白血病HL-60细胞凋亡的作用. 方法 实验分对照组和DADS处理组,进行体外细胞培养,进行细胞形态学观察,应用流式细胞术检测凋亡率、早期凋亡细胞以及caspase-3活性. 结果 DADS诱导前后,HL-60细胞形态学发生明显改变,PI单染法检测结果 :随着不同浓度DADS作用HL-60细胞24 h,HL-60细胞出现明显亚二倍峰,细胞周期也发生了相应的改变;Annexin V/PI 双染法检测结果 :10 mg/L DADS作用HL-60细胞4、8、12和24 h后,早期凋亡细胞显著增加,具有明显的时间依赖性(P<0.05);间接免疫荧光流式细胞术结果 显示在DADS诱导HL-60细胞凋亡过程中有caspase-3的活化,且与作用时间呈依赖关系. 结论 流式细胞术检测结果 表明,DADS能有效诱导HL-60细胞凋亡.     

二烯丙基二硫启动人白血病HL-60细胞凋亡模型的建立

目的寻找二烯丙基二硫(diallyl disulfide,DADS)诱导人白血病HL-60细胞凋亡的启动点,建立DADS启动HL-60细胞凋亡模型。方法实验设未处理组、处理组和撤药组,分别采用细胞计数、流式细胞术、DNA凝胶电泳、Western blot等方法,绘制生长曲线,检测凋亡率、活化的caspase-3表达率以及DNALadder、凋亡相关蛋白的检测。结果3.6mg.L-1DADS作用HL-60细胞1d,与对照组相比,细胞数没有明显变化,而作用2～6d,细胞数分别减少24.1%、36.5%、44.2%、52%、53.6%。DADS作用1、2d,凋亡率分别为3.1%、4.3%,与未处理组(3.0%)差异无显著性,而作用3～5d的凋亡率分别达到8.5%,15.2%,27.4%,均高于未处理组(P<0.05)。DADS作用2～5d撤药后再培养至d6,凋亡率分别为7.9%,12.4%,16.5%,18.8%,高于未处理组的3.3%(P<0.05)。处理2～5d后,活化的caspase-3的表达率分别为10.0%、10.4%、14.9%、17.3%,均高于未处理组5.4%(P<0.05)。处理组中DADS处理4d后DNA凝胶电泳出现梯状条带,而DADS作用2～5d撤药后再培养至d6均出现明显梯状条带。Westernblot结果表明,从作用2d起,caspase-3表达开始上调,而Bcl-2表达开始下调。结论3.6mg.L-1DADS诱导人白血病HL-60细胞凋亡的启动点为处理2d。     

二烯丙基二硫对小鼠肾包膜下移植人胃癌细胞的生长抑制作用

二烯丙基二硫(diallyl disulfide,DADS)是大蒜的主要有效成分,对多种肿瘤均有明显的抑制作用[1].本室体外研究表明:DADS可明显抑制人胃癌MGC803细胞生长[2],其机制与G2/M期阻滞和信号传导通路ERK/AP-1途径有关[3,4].本研究采用人肿瘤细胞肾包膜下移植模型,探讨DADS对体内生长的MGC803细胞的抑制作用.     

Cancer chemoprevention by dietary polyphenols: Promising role for epigenetics

Epigenetics refers to heritable changes that are not encoded in the DNA sequence itself, but play an important role in the control of gene expression. In mammals, epigenetic mechanisms include changes in DNA methylation, histone modifications and non-coding RNAs. Although epigenetic changes are heritable in somatic cells, these modifications are also potentially reversible, which makes them attractive and promising avenues for tailoring cancer preventive and therapeutic strategies. Burgeoning evidence in the last decade has provided unprecedented clues that diet and environmental factors directly influence epigenetic mechanisms in humans. Dietary polyphenols from green tea, turmeric, soybeans, broccoli and others have shown to possess multiple cell-regulatory activities within cancer cells. More recently, we have begun to understand that some of the dietary polyphenols may exert their chemopreventive effects in part by modulating various components of the epigenetic machinery in humans. In this article, we first discuss the contribution of diet and environmental factors on epigenetic alterations; subsequently, we provide a comprehensive review of literature on the role of various dietary polyphenols. In particular, we summarize the current knowledge on a large number of dietary agents and their effects on DNA methylation, histone modifications and regulation of expression of the non-coding miRNAs in various in vitro and in vivo models. We emphasize how increased understanding of the chemopreventive effects of dietary polyphenols on specific epigenetic alterations may provide unique and yet unexplored novel and highly effective chemopreventive strategies for reducing the health burden of cancer and other diseases in humans.     

A cell-based system to identify and characterize the molecular mechanism of drug-metabolizing enzyme (DME) modulators

Many naturally occurred or synthetic compounds can modulate the body's drug-metabolizing enzymes to enhance carcinogen detoxification, and some have demonstrated remarkable cancer prevention effects. Understanding the molecular mechanism behind each candidate agent is critically important in designing rational cancer chemoprevention strategies. In this work, we have employed a set of molecular mechanism-based assays and characterized eight classes of known drug-metabolizing enzyme (DME) modulators in a cellular system. Examination of mRNA and protein levels of representative phase I and phase II enzymes validated the results obtained in our cell-based system. Our data confirmed that the antioxidant ethoxyquin (EQ) and the isothiolcyanate sulfurophane (SFP) exclusively activate the antioxidant response element (ARE), and thus represent monofunctional inducers. We were also able to reclassify some compounds, and to use the system to identify structure-activity relationships among structurally related but different compounds. Finally, this cell-based system permitted us to identify a potential novel mechanism for cross-talk between the ARE and the xenobiotic response element (XRE)-mediated pathways.