Anticarcinogenic antioxidants as inhibitors against intracellular oxidative stress

Oxidative stress has been implicated in the pathogenesis of numerous diseases, including cancer. In the present study, the protective effect of natural antioxidants, such as quercetin and tea polyphenols, on intracellular oxidative stress was studied. Here we report a novel function of quercetin and tea polyphenols, as potential inhibitors of 4-hydroxy-2-nonenal (HNE)-induced intracellular oxidative stress and cytotoxicity. In rat liver epithelial RL34 cells, a potent electrophile HNE dramatically induced the productions of reactive oxygen species (ROS), which correlated well with the reduction in cell viability. We found that quercetin and tea polyphenols, such as epigallocatechin gallate and theaflavins and their gallate esters, significantly inhibited the HNE-induced ROS production and cytotoxicity. In addition, HNE induced a transient decrease in the mitochondrial membrane potential (Δψ), which was also retarded by the antioxidants. These data suggest that the antioxidants, such as quercetin and tea polyphenols, are inhibitors against mitochondrial ROS production.     

钾对兰州百合鳞茎中多酚类物质积累代谢及其抗氧化活性的影响

为探究施钾对兰州百合鳞茎中多酚类物质的积累、抗氧化能力及差异代谢物的影响,该研究以兰州百合鳞茎为试材,通过固定氮素(N)和磷素(P)用量,设置不同钾(K)浓度处理,即K_(0)(不施肥)、K_(1)(447.6 mg·L^(-1))、K_(2)(671.4 mg·L^(-1))、K_(3)(895.2 mg·L^(-1)),采用福林-肖卡法、溴甲酚绿比色法、香草醛比色法、DPPH法、铜离子还原能力(CUPRAC)法测定不同K浓度处理下兰州百合鳞茎中多酚类物质含量及其抗氧化活性,并采用LC-MS法分析多酚类物质的差异代谢物,并进行差异代谢物筛选,功能注释及富集分析,为兰州百合的优质栽培提供理论依据。结果表明:(1)不同K浓度处理下兰州百合鳞茎中多酚类物质的含量及其抗氧化活性存在显著差异(P<0.05),与K_(0)相比,K_(1)、K_(2)、K_(3)均能促进鳞茎多酚类物质的积累及其抗氧化能力的提高,其中以K_(2)(671.4 mg·L^(-1))效果最佳。(2)相关性分析表明,兰州百合鳞茎多酚类物质含量与抗氧化活性指标呈极显著(P<0.01)相关关系,相关系数为0.451~0.959。(3)K_(0)、K_(2)浓度处理下兰州百合鳞茎中存在89种多酚类及相关化合物,其中52种相对含量显著上调,37种相对含量显著下调,且显著富集到黄酮类及苯丙类化合物生物合成的通路上。研究认为,兰州百合的最佳施钾量(671.4 mg·L^(-1))能有效促进鳞茎中多酚类物质的积累并提高其抗氧化能力。     

Mosquito larval consumption of toxic arborescent leaf-litter,and its biocontrol potential

Previously we described the mosquito larvicidal properties of decomposed leaf-litter from deciduous trees, especially the alder Alnus glutinosa (L) Gaertn., due to toxic polyphenols and other secondary compounds. To further examine the biocontrol potential of toxic leaf-litter for mosquito control, feeding rates of third-instar mosquito larvae were assessed for examples of three genera: Anopheles stephensi Liston, Aedes aegypti (L) and Culex pipiens L. (Diptera: Culicidae). When immersed in a suspension of non-toxic leaf-litter particles (approximately 0.4 mm), pre-starved larvae of all three species ingested sufficient material in 30 min to fill the anterior gut lumen (thorax plus two to three abdominal segments). Gut filling peaked after 1-2 h ingestion time, filling the intestine up to six to seven abdominal segments for Ae. aegypti, but maxima of five abdominal segments for Cx. pipiens and An. stephensi. Using three methods to quantify consumption of three materials by third-instar larvae of Ae. aegypti, the average amount of leaf-litter (non-toxic 0.4 mm particles) ingested during 3 h was determined as approximately 20 microg/larva (by dry weight and by lignin spectrophotometric assay). Consumption of humine (approximately 100 microm particles extracted from leaf-litter) during 3 h was approximately 80 microg/larva for Ae. aegypti, but only approximately 30 microg/larva for Cx. pipiens and 15 microg/larva for An. stephensi, with good concordance of determinations by dry weight and by radiometric assay. Cellulose consumption by Ae. aegypti was intermediate: approximately 40 microg/larva determined by radiometric assay. Apparent differences between the amounts of these materials ingested by Ae. aegypti larvae (humine four-fold, cellulose two-fold more than leaf-litter) may be attributed to contrasts in palatability (perhaps related to particle size or form), rather than technical discrepancies, because there was good concordance between results of both methods used to determine the amounts of humine and leaf-litter ingested. Bioassays of toxic leaf-litter (decomposed 10 months) with 4-h exposure period (ingestion time) ranked the order of sensitivity: Ae. aegypti (LC50 < 0.03 g/L) > An. stephensi (LC50 = 0.35 g/L) > Cx. pipiens (LC20 > 0.4 g/L). When immersed in the high concentration of 0.5 g/L toxic leaf-litter (0.4 mm particles), as little as 15-30 min ingestion time (exposure period) was sufficient to kill the majority of larvae of all three species, as soon as the gut lumen was filled for only the first few abdominal segments. Possibilities for mosquito larval control with toxic leaf-litter products and the need for standardized ingestion bioassays of larvicidal particles are discussed.     

Antioxidant activity of fractionated extracts of rhizomes of high-altitude Podophyllum hexandrum: Role in radiation protection

Whole extract of rhizomes of Podophyllum hexandrum has been reported earlier by our group to render whole-body radioprotection. High-altitude P. hexandrum (HAPH) was therefore fractionated using solvents of varying polarity (non-polar to polar) and the different fractions were designated as, n-hexane (HE), chloroform (CE), alcohol (AE), hydro-alcohol (HA) and water (WE). The total polyphenolic content (mg% of quercetin) was determined spectrophotometrically, while. The major constituents present in each fraction were identified and characterized using LC-APCI/MS/MS. In vitro screening of the individual fractions, rich in polyphenols and lignans, revealed several bioactivities of direct relevance to radioprotection e.g. metal-chelation activity, antioxidant activity, DNA protection, inhibition of radiation (250 Gy) and iron/ascorbate-induced lipid peroxidation (LPO). CE exhibited maximum protection to plasmid (pBR322) DNA in the plasmid relaxation assay (68.09% of SC form retention). It also showed maximal metal chelation activity (41.59%), evaluated using 2,2-bipyridyl assay, followed by AE (31.25%), which exhibited maximum antioxidant potential (lowest absorption unit value: 0.0389± 0.00717) in the reducing power assay. AE also maximally inhibited iron/ascorbate-induced and radiation-induced LPO (99.76 and 92.249%, respectively, at 2000 g/ml) in mouse liver homogenate. Under conditions of combined stress (radiation (250 Gy) + iron/ascorbate), at a concentration of 2000 g/ml, HA exhibited higher percentage of inhibition (93.05%) of LPO activity. HA was found to be effective in significantly (p < 0.05) lowering LPO activity over a wide range of concentrations as compared to AE. The present comparative study indicated that alcoholic (AE) and hydro-alcoholic (HA) fractions are the most promising fractions, which can effectively tackle radiation-induced oxidative stress.     

Involvement of lignin peroxidase in the decolourization of black olive mill wastewaters by Geotrichum candidum

AIM: Decolourization of black olive mill wastewaters (OMW) by depolymerization of phenolic compounds by Geotrichum candidum. METHODS AND RESULTS: Our results show that G. candidum is able to grow on black OMW supplemented with carbon source and nitrogen. The Geotrichum growth decreased the pH and induced a 49% of colour removal when the black OMW was supplemented with glycerol and diammonium tartrate (20 mm ammonium). An improvement of 10% of colour removal was observed when the culture was supplemented with veratryl alcohol. The decolourization was inhibited with glutamate as nitrogen source. CONCLUSION: Our results suggest the potential use of G. candidum in black OMW decolourization and support the concept that lignin peroxidase (LiP) of G. candidum is involved in the depolymerization of phenolic compounds. Significance and Impact of the Study: This is the first report of LiP production by G. candidum on OMW.     

Metabolic profiling in validation of plasma biomarkers for green tea polyphenols

Green tea polyphenols (GTP) effectively protect against chronic diseases in various animal models but human studies have been inconclusive. GTP components and metabolites in body fluids have been suggested as potential biomarkers, but validation of these biomarkers has rarely been done in human populations. A randomized, double-blinded, and placebo-controlled phase IIa chemoprevention study with GTP was conducted in 120 human subjects for 3 months. To validate GTP biomarker profiles, plasma samples were collected at baseline, 1-month, and 3-month and were analyzed by HPLC-Coularray electrochemical detection (ECD) for specific GTP components as well as for non-targeted metabolites. The levels of 2 GTP components, epigallocatechin-3-gallate (EGCG) and epicatechin-3-gallate (ECG), were homogenous at baseline (p > 0.45) but were significantly elevated (p < 0.01) by GTP treatment. Metabolic profiling identified 106 metabolites, and 56 of them were chosen to construct discriminant functions (DFs) based on the data at 3 months. The DFs clearly separated the placebo, 500 mg GTP, and 1000 mg GTP groups with an accuracy rate of 97.3%. When the DFs were applied to the combined baseline and 1-month data, the accuracy rate was 62.9% in classifying subjects into the 3 intervention groups. DFs derived from 1-month data showed similar results. Overall, this study validated plasma EGCG and ECG as reliable biomarkers for GTP consumption, and found metabolic profiles effective in discriminating different GTP dosages.     

Angiogenesis and Inflammation Signaling Are Targets of Beer Polyphenols on Vascular Cells

Emerging evidence indicates that chronic inflammation and oxidative stress cluster together with angiogenic imbalance in a wide range of pathologies. In general, natural polyphenols present health‐protective properties, which are likely attributed to their effect on oxidative stress and inflammation. Hops used in beer production are a source of polyphenols such as xanthohumol (XN), and its metabolites isoxanthohumol (IXN) and phytoestrogen 8‐prenylnaringenin (8PN). Our study aimed to evaluate XN, IXN, and 8PN effects on angiogenesis and inflammation processes. Opposite in vitro effects were observed between 8PN, stimulating endothelial and smooth muscle cell (SMC) growth, motility, invasion and capillary‐like structures formation, and XN and IXN, which inhibited them. Mouse matrigel plug and rat skin wound‐healing assays confirmed that XN and IXN treatments reduced vessel number as well as serum macrophage enzymatic activity, whereas 8PN increased blood vessels formation in both assays and enzyme activity in the wound‐healing assay. A similar profile was found for serum inflammatory interleukin‐1β quantification, in the wound‐healing assay. Our data indicate that whereas 8PN stimulates angiogenesis, XN and IXN manifested anti‐angiogenic and anti‐inflammatory effects in identical conditions. These findings suggest that the effects observed for individual compounds on vascular wall cells must be carefully taken into account, as these polyphenols are metabolized after in vivo administration. The modulation of SMC proliferation and migration is also of special relevance, given the role of these cells in many pathological conditions. Furthermore, these results may provide clues for developing useful therapeutic agents against inflammation‐ and angiogenesis‐associated pathologies. J. Cell. Biochem. 111: 1270–1279, 2010. © 2010 Wiley‐Liss, Inc.     

刺山柑多酚类物质含量及其抗氧化活性研究

采用Folin-Ciocalteu法,测定南疆地区刺山柑不同时期不同器官多酚类物质含量,并用DPPH法对其抗氧化活性进行比较研究。结果表明:(1)多酚类物质在不同时期刺山柑不同器官中均有分布,刺山柑不同器官中花蕾中多酚类物质含量最高,茎中多酚类物质含量最少;其中5～8月份花蕾中多酚类物质含量随月份的增加而减少,茎中多酚类物质含量随月份的增加而增加,其他器官中多酚类物质含量变化与花蕾基本相似。(2)不同时期刺山柑的不同器官均有清除DPPH自由基的能力,花蕾的抗氧化活性最强,且花蕾的抗氧化活性随月份的增加而减弱,茎的抗氧化活性最弱。     

海芦笋及其生物盐中多酚酸和绿原酸的定量分析

以绿原酸为对照品,利用紫外分光光度法和高效液相色谱法分别建立了测定海芦笋中多酚酸和绿原酸含量的方法.紫外分光光度法检测波长为338 nm;高效液相色谱法采用Zorbax Eclipse XDB-C187(4.6 mm×150mm,5um),以甲醇和0.5％冰醋酸水溶液梯度洗脱.结果发现海芦笋及其生物盐中含有大量的多酚酸和绿原酸,其中多酚酸含量分别为6.49 g/kg,3.37 g/kg,绿原酸含量分别为0.234 9/kg,0.180 g/kg.同时也表明高效液相色谱法可用于海芦笋中多酚酸含量的确定.这两种简单快捷的定量分析多酚酸和绿原酸的方法,不仅可用于海芦笋及其生物盐产品的质量控制,而且也为海芦笋的进一步研究和开发提供了一定的依据.     

Trivanillic polyphenols with anticancer cytostatic effects through the targeting of multiple kinases and intracellular Ca2+ release

Cancer cells exhibit de-regulation of multiple cellular signalling pathways and treatments of various types of cancers with polyphenols are promising. We recently reported the synthesis of a series of 33 novel divanillic and trivanillic polyphenols that displayed anticancer activity, at least in vitro, through inhibiting various kinases. This study revealed that minor chemical modifications of a trivanillate scaffold could convert cytotoxic compounds into cytostatic ones. Compound 13c, a tri-chloro derivative of trivanillic ester, displayed marked inhibitory activities against FGF-, VEGF-, EGF- and Src-related kinases, all of which are implicated not only in angiogenesis but also in the biological aggressiveness of various cancer types. The pan-anti-kinase activity of 13c occurs at less than one-tenth of its mean IC(50) in vitro growth inhibitory concentrations towards a panel of 12 cancer cell lines. Of the 26 kinases for which 13c inhibited their activity by >75%, eight (Yes, Fyn, FGF-R1, EGFR, Btk, Mink, Ret and Itk) are implicated in control of the actin cytoskeleton organization to varying degrees. Compound 13c accordingly impaired the typical organization of the actin cytoskeleton in human U373 glioblastoma cells. The pan-anti-kinase activity and actin cytoskeleton organization impairment provoked by 13c concomitantly occurs with calcium homeostasis impairment but without provoking MDR phenotype activation. All of these anticancer properties enabled 13c to confer therapeutic benefits in vivo in a mouse melanoma pseudometastatic lung model. These data argue in favour of further chemically modifying trivanillates to produce novel and potent anticancer drugs.