褐藻多酚对晚期糖基化终产物的抑制作用研究

目的 研究褐藻多酚对晚期糖基化终产物(advanced glycation end products,AGEs)生成的抑制作用及其机制.方法 建立牛血清蛋白与葡萄糖体外模拟体系及食品热加工鱼肉肠模型,以不同浓度褐藻多酚为抑制剂,研究其对AGEs生成的抑制作用;通过分析模拟体系中赖氨酸和葡萄糖含量、蛋白质巯基水平及葡萄糖...     

焙炒对米茶中丙烯酰胺和晚期糖基化终产物的影响

研究焙炒温度、时间、加水量和浸润时间对米茶加工过程中丙烯酰胺(Acrylamide,AA)和晚期糖基化终产物(Advanced glycation end products,AGEs)的影响。结果表明,随着焙炒温度升高和时间的增加,AA和AGEs含量增加,但是当温度高于200℃时AA含量会呈现降低趋势;随加水量增加和浸润时间延长,AGEs含量显著性减少(p<0.05),米茶中的AA含量先降低,在加水量超过10%,浸润时间超过10 min之后升高。在190℃,加水量10%(w/w),浸润10 min,焙炒35 min最适加工条件下AA和AGEs含量分别为141μg/kg和360 AU/g,低于同类产品,正常食用对人体安全。      

Inhibition of the formation of advanced glycation end products by thymoquinone

The inhibitory activity of thymoquinone, a major quinone from black seeds (Nigella sativa) against the formation of advanced glycation end products was studied using the hemoglobin-δ-gluconolactone, human serum albumin–glucose, and the N-acetyl-glycyl-lysine methyl ester–ribose assays. A comparison was made with the inhibitory activity of aminoguanidine. The cytotoxicity of thymoquinone was studied by the release of lactate dehydrogenase from platelets and the levels of plasma thiols. At 20 μM, thymoquinone inhibited 39% of hemoglobin glycation, 82% of post-Amadori glycation products, reduced methyglyoxal-mediated human serum albumin glycation by 68%, inhibited 78% of late glycation end products. Aminoguanidine at 10 mM was less effective than thymoquinone. The IC₅₀ for thymoquinone and aminoguanidine were 7.2 μM and 1.25 mM, respectively. Thymoquinone at 20–50 μM was not toxic to platelet lactate dehydrogenase and plasma thiols. The potential of thymoquinone in food applications is discussed.     

肉制品加工过程中晚期糖基化终产物形成、检测及抑制研究进展

晚期糖基化终产物(advanced glycation end products, AGEs)是还原糖的羰基与蛋白质、脂质或核酸的游离氨基通过美拉德反应等途径产生的一系列结构复杂的化合物总称。目前已有不少研究证明AGEs在体内的积累会导致衰老、糖尿病、阿尔兹海默症等相关慢性疾病的发生, 也会引起肿瘤的发展与恶化。近年来, 随着国民生活水平的不断提高, 肉制品消费的不断增加, 其加工过程中AGEs的生成逐渐引起广泛关注。本文阐述了肉类加工过程中AGEs的结构、分类、形成途径与机制、检测方法, 总结了在不同加工方式下, 采用不同检测方法测量肉类中羧甲基赖氨酸和羧乙基赖氨酸的含量, 并重点介绍了AGEs形成的影响因素及其抑制, 旨在为肉制品加工过程中AGEs的生成控制等深入研究提供理论基础。     

Accumulation and effects of dietary advanced glycation end products on the gastrointestinal tract in rats

The gastrointestinal (GI) tract represents the first barrier against the penetration of organisms by dietary advanced glycation end products (AGEs), but the tissue accumulation of AGEs and AGE‐induced effects on the GI tract have yet to be completely elucidated. This study aimed to investigate the tissue accumulation of AGEs and AGE‐induced oxidative stress and inflammation in the GI tract of rats after long‐term consumption of AGEs from bread crust (BC). The GI tract was then removed to analyse carboxymethyllysine (CML) and malondialdehyde (MDA) contents, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) and the levels of tumour necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6). This study demonstrates that the oral intake of AGEs promotes their accumulation in the GI tract, and AGEs attenuate the first‐line antioxidant defence and stimulate the inflammatory response of the GI tract by downregulating enzymatic antioxidative pathways and increasing inflammatory cytokine levels.     

炸制过程中油脂氧化对鱼饼中晚期糖基化终末产物生成的影响

旨在为炸制鱼饼中晚期糖基化终末产物(AGEs)含量的控制提供理论依据和参考,以冷冻鲢鱼糜为原料制作鱼饼,通过分析连续炸制过程中(每3 h炸制1次)鱼饼中AGEs的生成与其理化指标和油脂氧化程度之间的相关性,探讨炸制过程中油脂氧化对鱼饼中AGEs生成的影响。结果表明：鱼饼外层AGEs含量显著高于内层,炸制9～18 h,鱼饼AGEs含量显著高于其他阶段(p<0.05);鱼饼中AGEs含量与水分含量呈极显著负相关,与脂肪含量和丙二醛含量呈极显著正相关,说明水分散失、油脂吸收以及油脂氧化促进了AGEs的生成。综上,在连续炸制过程的中期,鱼饼中水分含量较低,油脂氧化较为严重,AGEs含量较高。     

Evaluation of advanced glycation end products and carbonyl compounds in patients with different conditions of oxidative stress

Advanced glycation end products (AGE) and dicarbonyl compounds accumulate in serum and tissues of patients with diabetes and chronic renal failure. Pentosidine, free pentosidine, glyoxal and methylglyoxal have been evaluated in plasma of diabetic patients with poor metabolic control at baseline and after the improvement of glycemic levels, and in plasma and peritoneal dialysate of patients with renal failure before and after 12 h of peritoneal dialysis. In diabetic patients, acceptable metabolic control was unable to normalize levels of pentosidine (after 2 and 10 months), glyoxal and methylglyoxal (after 2 months). In patients with end-stage renal disease, mean values of pentosidine, free pentosidine, glyoxal and methylglyoxal decreased in plasma after dialysis. No pentosidine or free pentosidine were present in the peritoneal dialysate at time 0, but were found after 12 h of peritoneal dialysis; glyoxal and methylglyoxal decreased after 12 h of dialysis. So, glyoxal and methylglyoxal, already present in the dialysis fluid, can react with the peritoneal matrix protein, giving a reason for the gradual loss of peritoneal membrane function often observed in patients undergoing long-term peritoneal dialysis.     

Effect of long‐term dietary administration of oregano and rosemary on the antioxidant status of rat serum,liver, kidney and heart after carbon tetrachloride‐induced oxidative stress

BACKGROUND: This study was performed on female Wistar rats allocated to eight groups of six animals each. Groups 1 and 2 were fed the basal diet, groups 3 and 4 were fed the basal diet supplemented with ground oregano at 20 g kg^?1 level, groups 5 and 6 were fed the basal diet supplemented with ground rosemary at 20 g kg^?1 level, while groups 7 and 8 were fed the basal diet supplemented with both oregano and rosemary, each at 20 g kg^?1 level. Following 6 weeks feeding, groups 2, 4, 6 and 8 were injected with CCl₄ at 1 mL kg^?1 body weight, and 6 h thereafter all animals were sacrificed. RESULTS: Administration of CCl₄ to the control rats enhanced (P < 0.05) aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) activities, decreased cholesterol and triglycerides content in serum, increased (P < 0.05) lipid peroxidation and decreased (P < 0.05) the ABTS radical cation, the hydroxyl anion radical, the superoxide anion radical, and the hydrogen peroxide scavenging activities in all tested tissues, as compared to the control. Feeding oregano, rosemary or both before CCl₄ treatment resulted in decline (P < 0.05) of the increase in AST, ALT and ALP activities, increase (P < 0.05) of cholesterol and triglycerides in serum, decrease (P < 0.05) of lipid peroxidation, and increase (P < 0.05) of the ABTS radical cation, hydroxyl anion radical, superoxide anion radical and hydrogen peroxide scavenging activity. CONCLUSION: The results of this study suggest that long‐term dietary administration of oregano and rosemary has the potential to quench free radicals and alleviate CCl₄‐induced oxidative stress in rats. Copyright © 2009 Society of Chemical Industry     

Stability of a soybean seed‐derived vaccine antigen following long‐term storage,processing and transport in the absence of a cold chain

BACKGROUND: Soybean seeds are rich in natural protein and are favorable environments for targeted protein expression. Soybeans represent an ideal platform for the production of novel vaccines that, in theory, do not require a cold chain. This study investigated the stability of a soybean‐derived antigen following long‐term storage, formulation, and shipment overseas in the absence of refrigeration. RESULTS: Transgenic seeds can be stored for more than 4 years at ambient temperature with no detectable loss of FanC antigen stability. Conventional processing methods utilizing heat, mechanical extraction and solvent extraction resulted in practical formulations that could be lyophilized, stored as dried milk powder and rehydrated in water without loss of FanC antigen stability. Overseas shipment of transgenic seed powder and soymilk formulations in the absence of a cold chain had no adverse effects on formulations or the FanC antigen. CONCLUSION: The feasibility of long‐term storage, processing and shipment of transgenic soy products in the absence of a cold chain was demonstrated. Soybeans represent a practical platform for development of novel vaccines to potentially address the worldwide need for vaccines that are cost‐effective, easy to formulate and can be manufactured, stored and transported without refrigeration. Copyright © 2009 Society of Chemical Industry