The inhibition effects of reactive oxygen species by Maillard reaction products in Caco‐2 cells

Maillard reaction products (MRPs) were prepared by heating a mixture of rice starch with different dextrose equivalents (DE 10, 30, 50 and 70) and glycine. The glycine was added to the sample pastes at the same molar concentration as the sugar contained in each sample. As the dextrose equivalent of rice starch increased, the browning intensity and fluorescence of the MRPs increased. The antioxidant properties of the MRPs were investigated by DPPH radical scavenging activity, reducing power, and phenolic content in a chemical system, and were evaluated by measuring reactive oxygen species levels and antioxidant enzymes activities in Caco‐2 cells. The darkest MRPs, MRPs‐4, showed the highest antioxidant activity and phenolic content among the samples; in addition, it inhibited the cellular oxidative stress. The decrease of cell viability and antioxidant enzymes activities caused by reactive oxygen species and apoptosis were recovered by MRPs‐4. Actually, the addition of the MRPs suppressed apoptosis by decreasing the proportion of cells in the sub‐G1 phase. Therefore, these MRPs, as compounds formed by the Maillard reaction, are considered to possess an effective antioxidant activity against oxidizable substrates.     

Effect of N-acetyl-cysteine on liposomal and muscle model oxidation induced by reactive oxygen, nitrogen, and sulfur

N-acetyl-cysteine (NAC), a naturally occurring thiol, is found in some fruits and vegetables, sometimes in concentrations higher than glutathione. The objective of this research was to determine the antioxidative effect of NAC in liposomal and muscle models challenged by different oxidizing systems, three that produce reactive oxygen species, two that produce reactive nitrogen species, and two that produce reactive sulfur. The antioxidative effect of cysteine and NAC was compared in the liposomes and NAC and BHT were compared in the muscle homogenates. Lipid hydroperoxides (LOOH), TBARS, and sulfydryls (protein and non-protein) were analyzed. Results indicated that NAC is a more effective inhibitor of lipid oxidation in systems induced by free radicals and reactive nitrogen than those that are induced by peroxides. NAC appears to be at least mildly antioxidative in both liposomal and muscle models, although it did not completely inhibit oxidation in liposomes and generally was not as effective as BHT in the muscle models.     

Scavenging effects of lotus seed extracts on reactive nitrogen species

The inhibitory effect of lotus (Nelumbo nicifera) seed extracts extracted with water (LSWE), ethyl acetate (LSEAE) and hexane (LSHE) on reactive nitrogen species, induced by DNA damage in macrophage RAW 264.7 cells, was investigated. The results showed that all extracts could inhibit nitric oxide accumulation in LPS-activated RAW 264.7 cells. The extracts in the range of 0.01–0.2 mg/ml showed a dose-dependent inhibitory effect on the accumulation of nitric oxide upon decomposition of sodium nitroprusside (SNP). The potency of inhibitory activity was in the order: LSEAE > LSWE > LSHE. The results of the comet assay indicated that the three extracts could inhibit DNA damage in macrophage RAW 264.7 cells induced by SNP. In addition, the three samples, at 0.2 mg/ml, showed 63%, 59%, and 38% inhibition of DNA damage in macrophage RAW 264.7 cells induced by peroxynitrite, respectively. All extracts tested were found to be potent peroxynitrite scavengers, capable of preventing the nitration of tyrosine. The data obtained suggest that lotus seed extracts might act as chemopreventers through reduction of excess amounts of nitric oxide.     

Protective effects of three smoke flavouring phenols on oxidative damage and nitric oxide production

In this study, the effects of three smoke flavouring phenols, including 4-methoxyphenol (4-MP), 4-ethyl-2-methoxyphenol (EMP), and 4-propenyl-2-methoxyphenol (isoeugenol), on oxidative damage and nitric oxide production, were examined. In the range 5–20 μM, EMP displayed the highest inhibitory effects on radical production and biomolecule oxidation in the acellular systems of the three smoke flavouring phenols. In addition, 4-MP, EMP and isoeugenol, in the range 5–20 μM, protected liver cells against tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity, correlating with protection against intracellular glutathione depletion. Meanwhile, the inhibitory effects of the three smoke flavouring phenols on nitric oxide (NO) generation, in lipopolysaccharide (LPS)-stimulated macrophages, increased with increasing concentrations. The decrease in NO production was attributed to the reduced inducible nitric oxide synthase (iNOS) expression in macrophages. These data suggested that the three smoke flavouring phenols, particularly EMP, show biological activities that contribute to antioxidation as well as anti-inflammation.     

洋葱皮乙醇提取物对生鲜猪肉色泽、脂质和蛋白质氧化稳定性的影响

为研究洋葱皮乙醇提取物(ethanol extract of onion skins,EEOS)对生鲜猪肉色泽褐变,脂肪和蛋白质氧化以及微生物侵染程度的影响,并与空白对照组和抗坏血酸(ascorbic acid,VC)处理组进行比较,以猪肉亮度值L?、红度值a?,以及高铁肌红蛋白(metmyoglobin,MetMb)...     

洋葱皮提取物对西式香肠抗氧化及品质的影响

通过测定酸价、过氧化值与硫代巴比妥酸值来监测西式香肠在储存过程中的脂肪氧化程度的变化,并采用色差、全质构分析等方法将洋葱皮提取物香肠与空白对照样品的品质进行比较,以考察洋葱皮提取物对西式香肠的色泽、质构以及氧化稳定性的影响。结果显示:洋葱皮提取物的添加量为0.5%时,不仅抑制了西式香肠脂肪的氧化,而且还改善了其色泽,降低了其硬度、弹性与咀嚼性。     

Effect of nitric oxide on reactive oxygen species and antioxidant enzymes in kiwifruit during storage

BACKGROUND: The accumulation of reactive oxygen species (ROS) in kiwifruit can cause oxidative damage during storage. Little research has been carried out on the effects of nitric oxide (NO) on oxidative damage to kiwifruit. Therefore the aim of the present study was to evaluate the ability of 0.5, 1 and 2 µmol L^?1 NO aqueous solutions to alleviate oxidative damage to kiwifruit during storage. RESULTS: The most marked effect was obtained with 1 µmol L^?1 NO solution, which significantly reduced the accumulation of malondialdehyde, superoxide and hydrogen peroxide, delayed the decrease in vitamins C and E, maintained the content of soluble solids, inhibited the activity of lipoxygenase and peroxidase and increased the activity of superoxide dismutase and catalase in kiwifruit during storage. The 0.5 µmol L^?1 NO solution was too weak to significantly affect the content of ROS and the activity of enzymes. However, treatment with 2 µmol L^?1 NO solution promoted the accumulation of ROS, decreased the activity of antioxidant enzymes and accelerated peroxidation in kiwifruit during storage. CONCLUSION By increasing the activity of antioxidant enzymes and maintaining the content of vitamins C and E, treatment with 1 µmol L^?1 NO aqueous solution could protect kiwifruit against oxidative damage caused by ROS during storage. Copyright © 2008 Society of Chemical Industry     

Chemistry and reactions of reactive oxygen species in foods

Reactive oxygen species (ROS) are formed enzymatically, chemically, photochemically, and by irradiation of food. They are also formed by the decomposition and the inter-reactions of ROS. Hydroxy radical is the most reactive ROS, followed by singlet oxygen. Reactions of ROS with food components produce undesirable volatile compounds and carcinogens, destroy essential nutrients, and change the functionalities of proteins, lipids, and carbohydrates. Lipid oxidation by ROS produces low molecular volatile aldehydes, alcohols, and hydrocarbons. ROS causes crosslink or cleavage of proteins and produces low molecular carbonyls from carbohydrates. Vitamins are easily oxidized by ROS, especially singlet oxygen. The singlet oxygen reaction rate was the highest in ss-carotene, followed by tocopherol, riboflavin, vitamin D, and ascorbic acid.     

Effects of the aqueous extract of sugarcane leaves on antimutation and nitric oxide generation

In this study, the effects of a water extract of sugarcane leaves (WSL) on antimutation and nitric oxide (NO) production were investigated. The results showed that WSL inhibited the mutagenicity of benzo[a]pyrene (BP), an indirect mutagen; and N-methyl-N′-nitrosoguanidine (MNNG), a direct mutagen toward Salmonella typhimurium TA 98 and TA 100. In addition, WSL, in the range of 0–0.4 mg/ml, showed superoxide inhibiting, NO scavenging, and reducing activity, as well as decreased lipid oxidative damage. In the range of 0–1 mg/ml, the inhibitory effect of WSL on NO generation in lipopolysaccharide (LPS) stimulated macrophages increased with increasing concentrations. A high performance liquid chromatography analysis revealed that the polyphenolic constituents, such as caffeic acid, ferulic acid, apigenin, and vitexin were present in WSL. These data suggested that WSL exhibiting biological activities could contribute to antimutation, anti-inflammation as well as antioxidation.     

麦麸酶解产物对糖尿病大鼠氧化应激损伤的保护作用

用四氧嘧啶制备SD大鼠糖尿病模型,以麦麸酶解产物(EHWB)为受试物,测定各实验组大鼠血糖,血清、肝脏和睾丸总抗氧化能力(T-AOC)及超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSHPx)和黄嘌呤氧化酶(XOD)活性及丙二醛(MDA)含量。结果表明,与糖尿病组相比,EHWB治疗组大鼠血糖明显降低,TAOC能力升高,GSHPx和SOD活性增强,XOD活性降低,MDA含量明显降低。表明EHWB具有显著降血糖和提高糖尿病大鼠抗氧化能力的作用。     

油茶总皂甙抑菌活性及清除活性氧能力初步研究

用溶剂法提取油茶饼中油茶总皂甙,经柱层析制备标准品标定有效成分含量为82.5%。以油茶皂甙为材料对枯草杆菌、大肠杆菌、金黄色葡萄球菌进行抑菌试验,结果表明均有抑制作用;其中对枯草杆菌和金黄色葡萄球菌抑制作用较强,20%浓度对三种细菌均具有致死作用,抑菌圈直径大小与油茶总皂甙浓度呈正相关;且初步测定油茶总皂甙清除活性氧能力强于维生素C。     

Soy isoflavone genistein induces cell death in breast cancer cells through mobilization of endogenous copper ions and generation of reactive oxygen species

Scope: Worldwide geographical variation in cancer incidence indicates a correlation between dietary habits and cancer risk. Epidemiological studies have suggested that populations with high isoflavone intake through soy consumption have lower rates of breast, prostate, and colon cancer. Isoflavone genistein in soybean is considered a potent chemopreventive agent against cancer. Although several mechanisms have been proposed, a clear anticancer action mechanism of genistein is still not known. Methods and results: Here, we show that the cytotoxic action of genistein against breast cancer cells involves mobilization of endogenous copper. Further, whereas the copper specific chelator neocuproine is able to inhibit the apoptotic potential of genistein, the molecules which specifically bind iron (desferroxamine mesylate) and zinc (histidine) are relatively ineffective in causing such inhibition. Also, genistein‐induced apoptosis in these cells is inhibited by scavengers of reactive oxygen species (ROS) implicating ROS as effector elements leading to cell death. Conclusions: As copper levels are known to be considerably elevated in almost all types of cancers, in this proof‐of‐concept study we show that genistein is able to target endogenous copper leading to prooxidant signaling and consequent cell death. We believe that such a mechanism explains the anticancer effect of genistein as also its preferential cytotoxicity towards cancer cells.     

The effects of green tea (–)‐epigallocatechin‐3‐gallate on reactive oxygen species in 3T3‐L1 preadipocytes and adipocytes depend on the glutathione and 67 kDa laminin receptor pathways

Green tea (–)‐epigallocatechin‐3‐gallate (EGCG) is known as to regulate obesity and fat cell activity. However, little information is known about the effects of EGCG on oxidative reactive oxygen species (ROS) of fat cells. Using 3T3‐L1 preadipocytes and adipocytes, we found that EGCG increased ROS production in dose‐ and time‐dependent manners. The concentration of EGCG that increased ROS levels by 180–500% was approximately 50 μM for a range of 8–16 h of treatment. In contrast, EGCG dose‐ and time‐dependently decreased the amount of intracellular glutathione (GSH) levels. EGCG was more effective than (–)‐epicatechin, (–)‐epicatechin‐3‐gallate, and (–)‐epigallocatechin in changing ROS and GSH levels. This suggests a catechin‐specific effect. To further examine the relation of GSH to ROS as altered by EGCG, we observed that exposure of preadipocytes and adipocytes to N‐acetyl‐L ‐cysteine (a GSH precursor) blocked the EGCG‐induced increases in ROS levels and decreases in GSH levels. These observations suggest a GSH‐dependent effect of EGCG on ROS production. While EGCG was demonstrated to alter levels of ROS and GSH, its signaling was altered by an EGCG receptor (the so‐called 67 kDa laminin receptor(67LR)) antiserum, but not by normal rabbit serum. These data suggest that EGCG mediates GSH and ROS levels via the 67LR pathway.