Phytochemicals in Cancer Prevention and Therapy: Truth or Dare?

A voluminous literature suggests that an increase in consumption of fruit and vegetables is a relatively easy and practical strategy to reduce significantly the incidence of cancer. The beneficial effect is mostly associated with the presence of phytochemicals in the diet. This review focuses on a group of them, namely isothiocyanate, curcumin, genistein, epigallocatechin gallate, lycopene and resveratrol, largely studied as chemopreventive agents and with potential clinical applications. Cellular and animal studies suggest that these molecules induce apoptosis and arrest cell growth by pleiotropic mechanisms. The anticancer efficacy of these compounds may result from their use in monotherapy or in association with chemotherapeutic drugs. This latter approach may represent a new pharmacological strategy against several types of cancers. However, despite the promising results from experimental studies, only a limited number of clinical trials are ongoing to assess the therapeutic efficacy of these molecules. Nevertheless, the preliminary results are promising and raise solid foundations for future investigations.     

Oxidative-induced retinal degeneration is attenuated by epigallocatechin gallate

The aim of this investigation was to determine whether an ingredient of green tea, epigallocatechin gallate (EGCG) could attenuate oxidative stress-induced degeneration of the retina as occurs in age-related macular degeneration (AMD) and glaucoma. Initial in vitro studies on brain membranes showed that EGCG was approximately 10 times more potent than trolox (vitamin E analogue) at attenuating lipid peroxidation caused by the nitric oxide donor, sodium nitroprusside (SNP). Subsequent immunohistochemical studies revealed that following an intraocular injection of SNP retinal photoreceptors are affected. This was supported by electroretinogram (ERG) recordings which showed both the a- and b-wave amplitudes to be significantly reduced. RT-PCR and Western blotting techniques showed that SNP caused a significant decrease in photoreceptor-specific markers (RET-P1, rhodopsin kinase), an increase in the cell death marker caspase-3, and no change in the ganglion cell specific markers, neurofilament (NF-L) and Thy-1. Importantly, when EGCG was co-injected, the detrimental effects to the retina caused by SNP were significantly blunted. The conclusion reached from this study is that EGCG is a powerful antioxidant and when injected into the eye with SNP attenuated the detrimental influence of SNP to retinal photoreceptors. Since oxidative stress has been implicated in retinal diseases like AMD and glaucoma this study provides "proof of principle" for the idea that daily intake of EGCG may help individuals suffering from retinal diseases where oxidative stress is implicated.     

Aspirin response evaluated by the VerifyNow Aspirin System and light transmission aggregometry

Introduction

Patients with inadequate platelet inhibition by aspirin, referred to as aspirin resistance, might have an increased risk of suffering cardiovascular events. Therefore, identification of these patients by measuring platelet function is of great interest. Our objectives were to evaluate performance parameters of VerifyNow™ and to determine the agreement between VerifyNow™ and light transmission aggregometry (LTA) ad modum Born.

Materials and Methods

We included 21 healthy volunteers and 40 patients with stable coronary artery disease. Duplicate measurements of platelet aggregation were performed using VerifyNow™ and LTA (arachidonic acid 1.0 mM) in healthy volunteers before aspirin and in all participants on four consecutive days during treatment with non-enteric-coated aspirin 75 mg daily. VerifyNow™ test results were expressed in Aspirin Reaction Units (ARU) and LTA test results in percent of maximal aggregation. The cut-off for determination of aspirin resistance was ≥ 550 ARU and ≥ 20%, respectively.

Results

All participants were compliant, confirmed by complete suppression of serum-thromboxane B₂. VerifyNow™ was highly repeatable with a coefficient of variance of 0.5% at baseline and 3.0% during aspirin treatment. No individuals were identified as aspirin resistant with VerifyNow™, whereas seven (12%) individuals were identified with LTA. ROC analysis using LTA as the gold standard showed poor sensitivity and good specificity with a cut-off at 550 ARU.

Conclusion

VerifyNow™ was highly repeatable, but further studies are needed to investigate the relevance of the cut-off level at 550 ARU for detecting aspirin resistance.     

Attenuation of the inflammatory changes and lipid anomalies by epigallocatechin-3-gallate in hypercholesterolemic diet fed aged rats

Epidemiological studies suggest that even in the absence of other risk factors advanced age itself significantly increases cardiovascular morbidity. Age aggravated inflammatory activity further plays a central role in the pathogenesis of atherosclerosis and its complications. EGCG, a major flavonoid present in green tea extract has been proved to be useful in lowering cholesterol levels thereby slowing down the progression of cardiovascular diseases in young animals. Thus, the endeavor of this study was to assess the impact of high-cholesterol diet on aging and vice versa and to exploit the potential of EGCG to combat age-associated hypercholesterolemia and mitigate inflammation. Male albino rats of Wistar strain (3 months-young and 24 months old-aged) were used in this study. Hypercholesterolemia was induced by the diet comprising of the normal rat chow supplemented with 4% cholesterol and 1% cholic acid. EGCG (100 mg/kg body weight/day) was given orally for 30 days. The results revealed abnormally elevated lipid levels, marker enzymes and inflammatory markers in serum of aged hypercholesterolemic rats when compared to young hypercholesterolemic rats, while treatment with EGCG partially reversed these aberrations. The present work demonstrates the inflammatory responses in hypercholesterolemic atherogenesis during aging and further underscores the salubrious role played by the EGCG in attenuating the inflammatory and lipid anomalies.     

棓丙酯对红细胞溶血和渗透脆性的影响

目的探讨棓丙酯是否可影响红细胞溶血及其渗透脆性。方法以不同浓度的棓丙酯（256μg/ml、128μg/ml、64μg/ml、32μg/ml、16μg/ml、8μg/ml）与红细胞悬液孵育12小时,肉眼观察和氰化高铁血红蛋白法测定溶血程度;红细胞渗透脆性试验检测药物处理后各组红细胞的最大脆性和最小脆性,再用氰化高棓铁血红蛋白法检测各组的最大脆性溶血情况。并用统计软件SPSS16.0对实验结果进行统计分析。结果肉眼观察和氰化高铁血红蛋白法显示不同浓度的棓丙酯处理后,各组红细胞悬液无明显溶血,各药物处理组的最大脆性和最小脆性与正常人和对照组的渗透脆性比较无显著差异;氰化高铁血红蛋白法检测各处理组的最大脆性溶血程度与对照组比较差异无显著性（P〉0.05）。结论棓丙酯对红细胞溶血和渗透脆性无影响。     

The protective effect of green tea catechins on ketamine-induced cystitis in a rat model

ObjectiveTo investigate the protective effect of green tea epigallocatechin gallate (EGCG) on long-term ketamine-induced ulcerative cystitis (KIC) using a ketamine addiction rat model.Materials and methodsThirty Sprague-Dawley rats were divided into three groups which received saline, ketamine (25 mg/kg/d), or ketamine combined with EGCG (10 μM/kg) for a period of 28 days. In each group, cystometry and a metabolic cage micturition pattern study were performed weekly. Masson's trichrome study was done to evaluate the morphologic changes. Western blot analyses were carried out to examine the expressions of inflammatory protein [transforming growth factor-β (TGF-β)] and fibrosis proteins (fibronectin and type I collagen) in bladder tissues.ResultsChronic ketamine treatment resulted in bladder hyperactivity with a significant increase in micturition frequency and a decrease in bladder compliance. These alterations in micturition pattern were accompanied by increases in the expressions of inflammatory and fibrosis markers, TGF-β, fibronectin, and type I collagen after long-term ketamine treatment. Masson's trichrome stain showed that ketamine treatment decreased urothelium thickness while increasing the collagen to smooth muscle ratio and exacerbating interstitial fibrosis. By contrast, simultaneous EGCG and ketamine treatment reversed ketamine-induced damage to almost control levels, showing the protective effect of EGCG.ConclusionThis protective effect of EGCG may come from its antiinflammatory and antifibrotic properties.     

Epigallocatechin gallate attenuates L-DOPA-induced apoptosis in rat PC12 cells

In this study, the protective effects of EGCG on L-3,4-dihydroxyphenylalanine (L-DOPA)-induced oxidative cell death in catecholaminergic PC12 cells, the in vitro model of Parkinson''s disease, were investigated. Treatment with L-DOPA at concentrations higher than 150 µM caused cytotoxicity in PC12 cells, as determined using the 3-(4,5-dimetylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry detection. The apoptotic ratio was similar in cells treated with 100 µM EGCG plus 150 µM L-DOPA (5.02%) and the control (0.96%) (P > 0.05), and was lower than that of cells treated with L-DOPA only (32.24%, P < 0.05). The generation level of ROS (% of control) in cells treated with EGCG plus L-DOPA was lower than that in cells treated with L-DOPA only (123.90% vs 272.32%, P < 0.05). The optical density in production of TBARS in cells treated with L-DOPA only was higher than that in the control (0.27 ± 0.05 vs 0.08 ± 0.04, P < 0.05), and in cells treated with EGCG only (0.14 ± 0.02, P < 0.05), and EGCG plus L-DOPA (0.13 ± 0.02, P < 0.05). The intracellular level of GSH in cells treated with EGCG plus L-DOPA was higher than that in cells treated with L-DOPA only (233.25 ± 16.44 vs 119.23 ± 10.25, P < 0.05). These results suggest that EGCG protects against L-DOPA-induced oxidative apoptosis in PC12 cells, and might be a potent neuroprotective agent.     

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.     

没食子酸丙酯对大鼠缺血再灌注心肌线粒体呼吸酶的影响

目的观察没食子酸丙酯对大鼠缺血再灌注心肌线粒体呼吸酶的影响。方法结扎大鼠冠状动脉30min再灌注20min,测定心肌线粒体中琥珀酸脱氢酶(SDH)、细胞色素氧化酶(CCO)、Ca2+·Mg2+-ATP酶、Ca2+-ATP酶活性及细胞色素、磷脂含量。结果没食子酸丙酯(20和40mg.kg1,结扎冠状动脉前60minip)能显著减轻缺血再灌注所致琥珀酸脱氢酶(SDH)、细胞色素氧化酶(CCO)、Ca2+·Mg2+-ATP酶、Ca2+-ATP酶活性的抑制(P<0.05),及细胞色素aa3、细胞色素C和膜磷脂含量的减少。结论没食子酸丙酯对缺血再灌注时心肌线粒体呼吸酶具有保护作用。