Association of metabolic syndrome risk factors with selected markers of oxidative status and microinflammation in healthy omnivores and vegetarians

Conditions predisposing to metabolic syndrome (MetS) are associated with increased oxidative stress and inflammation. We studied, in vegetarians (n = 90) and omnivores (n = 46), the impact of the dietary regimen on the occurrence of MetS risk factors (RFs: BMI, blood pressure, glucose metabolism and lipid profile) in relation to oxidative status (advanced glycation end products (AGEs), advanced oxidation protein products (AOPPs), malondialdehyde, ferric reducing ability of plasma, vitamins A, E, C, beta-carotene and superoxide dismutase activity) and microinflammation (C-reactive protein, leukocytes and neopterin). The proportion of subjects without/positive for one or two MetS RFs was comparable between the groups. From the components of MetS only immunoreactive insulin levels differed significantly (95% CI: omnivores: 5.0-7.1 microU/mL, vegetarians: 4.5-5.4, p = 0.03). Omnivores had lower AOPP (omnivores: 0.29-0.36 micromol/g albumin, vegetarians: 0.36-0.52, p = 0.01) and beta-carotene levels than vegetarians, they consumed more calories, proteins, fat and saturated fatty acids, and less fibres, beta-carotene and vitamin C. Multiple regression analysis revealed vitamin E and AOPP levels as the most important independent determinants of MetS RFs. The vegetarian diet seems to exert beneficial effects on MetS RFs associated microinflammation. Whether the vegetarian diet may counteract the deleterious effects of elevated AOPPs and AGEs, remains to be elucidated.     

Inhibitory effects of guava (Psidium guajava L.) leaf extracts and its active compounds on the glycation process of protein

Hyperglycaemia causes increased protein glycation and the formation of early glycation products and advanced glycation end products (AGEs) which are major factors responsible for the complications of diabetes. This study investigated the ability of guava leaf and compounds to inhibit glycation process in an albumin/glucose model system and compared the potency of these extracts with Polyphenon 60 which is a commercial polyphenol product extracted from green tea and with the standard antiglycation agent, aminoguanidine. The results showed that the inhibitory effects of guava leaf extracts on the formation of α-dicarbonyl compounds were over 95% at 50 μg/ml. Phenolic compounds present, namely gallic acid, catechin and quercetin exhibited over 80% inhibitory effects, but ferulic acid showed no activity. The guava leaf extracts also showed strong inhibitory effects on the production of Amadori products and AGEs from albumin in the presence of glucose. The phenolic compounds also showed strong inhibitory effects on the glycation of albumin, especially quercetin exhibited over 95% inhibitory effects at 100 μg/ml. According to the results obtained, guava leaf extracts are potent antiglycation agents, which can be of great value in the preventive glycation-associated complications in diabetes.     

不饱和脂肪酸对卵清蛋白糖基化反应的影响

糖基化反应是高营养食品常见的一类反应,食品中的脂类成分对糖基化反应有很大影响.本研究以葡萄糖和卵清蛋白(OVA)建立糖基化对照体系,与含有不饱和脂肪酸(UFA)的模型组进行对比,探究脂肪酸氧化对于糖基化反应产物二羰基化合物、晚期糖基化终产物(AGEs)及糖基化蛋白结构的影响.结果表明UFA通过不同方式促进二羰基化合物的...     

Dietary AGEs and ALEs and risk to human health by their interaction with the receptor for advanced glycation endproducts (RAGE)--an introduction

The receptor for advanced glycation endproducts (RAGE) has a well-substantiated role in cell dysfunction and mechanisms of inflammatory disease. The physiological agonists of RAGE are less certain: S100/calgranulin proteins, high mobility group-1 protein HMGB1 and other proteins are candidate agonists. It increasingly appears unlikely proteins modified by advanced glycation endproducts are effective agonists in vivo. In the following debate, Professors Ann Marie Schmidt and Claus Heizmann gave arguments and evidences for and against the motion. Recent evidence suggesting the activation of RAGE impairs the enzymatic defence against glycation provided by glyoxalase 1 (Glo 1) suggests that studies of RAGE will continue to be of importance to our understanding of the physiological significance of protein glycation.     

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.     

Neoformation of antioxidants in glycation model systems treated under subcritical water extraction conditions

In this work, the possibility of finding newly formed Maillard reaction products produced as a result of the subcritical water extraction (SWE) conditions is explored. Simplified powdered glycation model systems were prepared mixing amino acid (Lys, Arg or Ala) and glucose in a molar ratio 1:4. Samples constituted by glucose or amino acids alone were also prepared as controls. SWE was carried out at room temperature, 100 °C and 200 °C and 100 bar of pressure for 20 min. Different assays were performed in order to determine the extent of glycation by analyzing the decrease of free amino groups and/or the formation of Maillard reaction products (early, advanced and end products). Namely, formation of early colorless Maillard reaction products, Amadori compounds, was detected by ESI-MS; advanced glycation end products (AGEs) were detected by measuring the fluorescence intensity (λ_ex = 360 nm, λ_em = 460 nm) while end brown products were detected by reading the absorbance at 360 and 420 nm. Besides, the antioxidant capacity of the aqueous extracts was determined by using ABTS and ORAC_FL assays. Results obtained indicated the occurrence of the Maillard reaction under our specific extraction conditions. Early, advanced and end products were detected in the samples. Caramelization of sugar also occurred. As expected, the extent of the non-enzymatic browning depended on the intensity of the thermal treatment. Additionally, data on antioxidant activity suggested the formation of neoantioxidants. These compounds were predominantly formed at 200 °C. In conclusion, this report demonstrates the formation of antioxidant compounds in simplified glycation model systems under SWE conditions.     

美拉德反应产物的生物学活性和潜在健康风险

富含碳水化合物、蛋白质和油脂的食品在热加工过程中会发生剧烈的美拉德反应,生成大量的美拉德反应产物。美拉德反应产物中存在的低分子质量化合物和类黑精等物质具有多种生物学活性,但是其中的晚期糖基化终末产物、丙烯酰胺等潜在风险因子会加速人体的衰老或导致慢性退行性疾病的发生。本文综述了美拉德反应产物的抗氧化、抗菌和抗炎等生物学活性,同时也探讨了美拉德反应产生的晚期糖基化终末产物和丙烯酰胺等有害化合物的损伤机制和预防措施,以期为美拉德反应的深入研究提供科学参考。     

Nε-(carboxymethyl)lysine formation from the Maillard reaction of casein and different reducing sugars

Food Science and Biotechnology - Dietary advanced glycation end products (AGEs) are involved in the pathogenesis of diabetic complications, atherosclerosis, and kidney disease. Formation of...     

Protein glycation inhibitory activity of wheat bran feruloyl oligosaccharides

Protein glycation is believed to play an important role in the development of long-term disorders associated with diabetes. Water-soluble feruloyl oligosaccharides (FOs) from wheat bran, the ferulic acid esters of oligosaccharides, have been reported as natural antioxidants. The present work assesses the chelating activity of FOs and their inhibition of protein glycation in a bovine serum albumin (BSA)/glucose system, using fluorescence spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). FOs exhibited an effective ferrous ion chelating activity, and quenched the fluorescence intensity of glycated BSA in a dose-dependent manner with 64.0% of inhibition at 1.0 mg/ml. Further, the formation of advanced glycation end products in the tested system was significantly decreased by FOs, as shown by SDS–PAGE. These data indicate that FOs might be beneficial as glycation inhibitors under specified conditions.     

Relation between serum xenobiotic-induced receptor activities and sperm DNA damage and sperm apoptotic markers in European and Inuit populations

Persistent organic pollutants (POPs) can interfere with hormone activities and are suspected as endocrine disrupters involved in disorders, e.g. reproductive disorders. We investigated the possible relation between the actual integrated serum xenoestrogenic, xenoandrogenic and aryl hydrocarbon receptor (AhR) activities, and the sperm DNA damage and sperm apoptotic markers of 262 adult males (54 Inuits from Greenland, 69 from Warsaw (Poland), 81 from Sweden, and 58 from Kharkiv (Ukraine)) exposed to different levels of POPs. Xenobiotic-induced receptor activities were determined by receptor-mediated luciferase reporter gene expression. Sperm DNA damage was measured using terminal deoxynucleotidyl transferase-driven dUTP nick labeling assay (TUNEL) and pro- (Fas) and anti-apoptotic (Bcl-xL) markers were determined by immune methods. Different features of xenobiotic-induced receptor activity in serum and sperm DNA fragmentation and apoptotic markers existed between the Inuits and the European Caucasians. Negative correlations between xenobiotic-induced receptor activities and DNA damage were found for Inuits having relatively lower xenoestrogenic, lower dioxin-like activity, and lower sperm DNA damage, but higher xenoandrogenic activity. In contrast, in the European groups, xenobiotic-induced receptor activities were found to be positively correlated with the DNA damage. Further research must elucidate whether altered receptor activities in concerted action with genetic and/or nutrient factors may have protecting effect on sperm DNA damage of the Inuit population.     

Synergistic antioxidant interaction between sugars and phenolics from a sweet wine

Musts from sun-dried grapes Pedro Ximénez are rich in polyphenols and sugars, and synergic effects between them have been found. Sugars participate in the stability of polyphenols; so, the autoxidation of (+)-catechin by ferrous iron is inhibited by a mixture of glucose and fructose similar to that found in musts of dried grapes. Phenolic fraction of musts was extracted with SepPack C18 cartridges, and the identification and quantification of phenolic compounds was achieved using HPLC-diode array detection. The evolution of phenolic content along the off-vine process indicated that there was a fourfold increase in most phenolics, catechin being the most abundant phenolic identified. Musts and the phenolic fractions showed a high antioxidant activity when determined by various established in vitro systems, namely β-carotene-linoleate bleaching assay, deoxyribose degradation and pBlueScript SK (-) DNA oxidation. The high antioxidant activity of musts found in the assays involving the formation of hydroxyl radicals, deoxyribose degradation, and DNA oxidation were partially due to the presence of sugars in the musts. The glycation of albumin was also studied by incubating BSA with a concentration of glucose and fructose, similar to that in musts; in these conditions, the phenolic fraction from must inhibited by a 76% the formation of advanced glycation end products (AGEs). A similar inhibition in the AGEs formation was observed when musts were directly incubated with albumin. The results indicate that musts and the phenolic fraction of sun-dried Pedro Ximénez grapes possess a marked antioxidant activity.     

Postnatal testicular development in mouse species with different levels of sperm competition

Postcopulatory sexual selection leads to an increase in sperm numbers which is partly the result of an increase in relative testes mass and could also be the consequence of changes in testis architecture or function. Very little is known regarding developmental changes during the first spermatogenic wave that may lead to enhanced spermatogenic efficiency and increased sperm production. We examined testicular development after birth in four mouse species with different sperm competition levels to assess changes in testicular architecture and function. Differences in relative testes mass between species appeared soon after birth and were exacerbated thereafter. The volume of testes occupied by seminiferous tubules differed between species postnatally and were associated with sperm competition levels. Finally, changes over time in the proportions of tubules with different germ cell types were also associated with sperm competition levels, with the time taken for the transition between various cell stages being negatively associated with levels of sperm competition. We conclude that postnatal testis development differs between closely related species with different sperm competition levels influencing testis architecture and the rate of progression of spermatogenesis, leading to differences in testis function at reproductive maturity.     

Inhibitory effects of Lemon balm (Melissa officinalis, L.) extract on the formation of advanced glycation end products

Lemon balm (Melissa officinalis) is a medicinal herb possessing functional compounds with unexplored anti-glycative action. The anti-glycative activity of Lemon balm extract was evaluated in the bovine serum albumin (BSA)/glucose system. The level of glycation, conformational alterations and protein binding to RAGE receptors were assessed by specific fluorescence, Congo red binding assay, circular dichroism, ligand and Western blotting. Ethanol fractions of Melissa leaf exhibited the highest inhibitory effects on the formation of advanced glycation end products (AGEs) and the late stage of glycation process. Significant alteration in the secondary structure of albumin was observed upon glycation, which was mitigated by applying the herb extract. Moreover, upon treatment with balm extract, glycated albumin adopts a secondary structure impeding its detection by RAGE receptors of microglial cells. Our results represent the anti-glycative properties of Melissa extract and its application for possible treatment of AGE-associated diseases.     

Methylglyoxal-derived advanced glycation end products induce matrix metalloproteinases through activation of ERK/JNK/NF-κB pathway in kidney proximal epithelial cells

Food Science and Biotechnology - The accumulation of reactive α-dicarbonyl leading to advanced glycation end products (AGEs) have been linked to pathophysiological diseases in many studies,...     

绿原酸防治2型糖尿病作用机制的研究进展

绿原酸是一类广泛存在于自然界中的酚酸化合物,常见于人类植物源饮食中,也是很多中药材的主要组分。研究表明,绿原酸具有调节肠道激素分泌、抑制胰岛素抵抗、减缓肝脏糖异生等作用。近年来,有关绿原酸调节糖代谢研究进一步深入,例如绿原酸可以抑制胰淀粉酶活性、抑制人胰岛淀粉样多肤形成、抑制醛糖还原酶和糖基化终末产物形成等。本文综述了绿原酸在调节糖脂代谢方面的作用机制和研究进展。     

Curcumin ameliorates methylglyoxal-induced alterations of cellular morphology and hyperpermeability in human umbilical vein endothelial cells

Endothelial dysfunction such as hyperpermeability is one of the characteristics in an early stage of diabetic complications. Curcumin has been shown to inhibit the formation of advanced glycation end products (AGEs) and to trap methyglyoxal (MGO) in cell-free system and in human umbilical vein endothelial cells (HUVECs). Here, we investigated the effect of curcumin on dysfunctions of HUVECs induced by exogenous MGO (30 μM), which significantly increased intracellular reactive oxygen species (ROS), endothelial permeability, and cytoskeleton rearrangement. In contrast, MGO decreased gap junctional intercellular communication and the expression of connexin 43 and zonula occludens. Pre-treatment of HUVECs with curcumin (0.25–2.5 μM) significantly ameliorated MGO-induced endothelial dysfunction, whereas pre-treatment with vitamin E (10 μM) only slightly ameliorated MGO-induced endothelial dysfunction, suggesting that ROS induced by MGO do not play a major role in endothelial dysfunction. These results suggest that curcumin is a potential protective agent against MGO-induced endothelial dysfunction.     

肠易激综合征饮食干预策略研究进展

肠易激综合征（Irritable Bowel Syndrome,IBS）是常见的胃肠道疾病之一,主要临床症状为腹痛、腹胀以及排便频率和性状异常。该病发病机制复杂,包括遗传因素、饮食差异、肠道菌群改变、胃肠道感染以及脑-肠轴异常等。目前缓解病症的主要方式是限制性饮食,如低“可发酵性寡糖、双糖、单糖和多元醇”（Fermentable Oligosaccharides,Disaccharides,Monosaccharides and Polyols,FODMAPs）饮食、低“晚期糖基化终产物”（Advanced Glycosylation End Products,AGEs）饮食、无麸质饮食以及低乳糖饮食等,能有效改善IBS患者的腹部不适症状。本文归纳了近几年国内外相关学者对于IBS的研究现状,包括IBS的病理生理学机制、低FODMAPs饮食和低AGEs饮食与IBS肠道菌群的关联、针对食物中FODMAPs成分和AGEs成分的定量检测手段以及食品加工处理技术降低食物中FODMAPs和AGEs含量的措施,以期为IBS患者提供健康有效的饮食干预策略。