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.     

Naturally occurring inhibitors against the formation of advanced glycation end-products

Advanced glycation end-products (AGEs) are the final products of the non-enzymatic reaction between reducing sugars and amino groups in proteins, lipids and nucleic acids. Recently, the accumulation of AGEs in vivo has been implicated as a major pathogenic process in diabetic complications, atherosclerosis, Alzheimer's disease and normal aging. The early recognition of AGEs can ascend to the late 1960s when a non-enzymatic glycation process was found in human body which is similar to the Maillard reaction. To some extent, AGEs can be regarded as products of the Maillard reaction. This review firstly introduces the Maillard reaction, the formation process of AGEs and harmful effects of AGEs to human health. As AGEs can cause undesirable diseases or disorders, it is necessary to investigate AGE inhibitors to offer a potential therapeutic approach for the prevention of diabetic or other pathogenic complications induced by AGEs. Typical effective AGE inhibitors with different inhibition mechanisms are also reviewed in this paper. Both synthetic compounds and natural products have been evaluated as inhibitors against the formation of AGEs. However, considering toxic or side effects of synthetic molecules present in clinical trials, natural products are more promising to be developed as potent AGE inhibitors.     

Inhibitory effect of fermentation byproducts on formation of advanced glycation end-products

Distilled residues (DR) of rice spirit and its derived vinegar produced a negligible inhibitory effect on advanced glycation end-products (AGE) formation. However, recycled DRs of rice spirit and barley spirit and their derived vinegars inhibited formation of N^ε(carboxymethyl)lysine (CML), a major AGE. Unlike the aforementioned DR and derived vinegars, the DR of sweet potato spirit and vinegar, contained very little protein, lysine and arginine, but they most potently inhibited CML formation. The DRs of various spirits and vinegars showed similar free radical-scavenging activities.     

香蕉茎秆汁液抑制晚期糖基化终末产物活性评价

为研究香蕉茎秆汁液抑制晚期糖基化终末产物（AGEs）活性,选用α-葡萄糖苷酶和α-淀粉酶抑制模型研究其对碳水化合物代谢关键酶的抑制作用,并采用Lineweaver-Burk双倒数法研究其动力学性质。同时对AGEs的抑制和清除ABTS⁺·的能力也进行了评价。结果表明,香蕉茎秆汁液对α-葡萄糖苷酶的半抑制浓度(IC₅₀)为1.51 mg/m L,对α-葡萄糖苷酶的抑制类型为混合型抑制。香蕉茎秆汁液对α-淀粉酶的半抑制浓度(IC₅₀)是8.64 mg/m L,抑制类型为不可逆抑制。通过实验研究,香蕉茎秆汁液具有一定清除ABTS⁺·的能力,对牛血清白蛋白果糖模型AGEs也具有一定的抑制作用。香蕉茎秆汁液可抑制体外AGEs的生成。      

Inhibitory efficacy of Ligularia fischeri against aldose reductase and advanced glycation end products formation

The efficacy of Ligularia fischeri (LF) for managing diabetic complications was evaluated by assessing inhibitory effects against advanced glycation end product (AGE) formation, rat lens aldose reductase (RLAR), and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging. The ethyl acetate fraction from 70% ethanol extracts of LF showed the highest DPPH radical scavenging activity of 53.90% at a concentration of 3.3 μg/mL. The ethyl acetate fraction exhibited the most potent AGE formation inhibition of 73.57% at a concentration of 55 μg/mL and showed the most potent RLAR inhibition of 88.97% at a concentration of 11.11 μg/mL. The ethyl acetate fraction exhibited the most potent antioxidant and anti-diabetic effects. Nuclear magnetic resonance via bioactivity-guided fractionation of the LF ethyl acetate fraction revealed that 3,4-dicaffeoylquinic acid was the bioactive compound. This compound from LF can be effective for prevention or treatment of diabetic complications.     

Effect of plant polyphenols on the formation of advanced glycation end products from β-lactoglobulin

Dietary exposure to advanced glycation end products (AGEs) formed from proteins and reducing sugars is of increasing concern to human health. AGEs may form in protein-based powders containing sugars for instant beverages during drying and storage of the product. Chlorogenic acid, a plant phenol characteristic of coffee, was found to protect against the formation of AGEs at a concentration of 50mM during heating of β-lactoglobulin in the presence of glucose as a reducing sugar in 30% aqueous ethanol at 70°C. Epicatechin, a plant phenol characteristic of green tea, had no similar effect for the equivalent concentration of phenol on the formation of AGEs. Immunochemical detection (ELISA) using polyclonal antibodies raised against AGEs showed a dose-dependent effect of protection by chlorogenic acid on AGE formation and is recommended for routine quality control of sugar containing milk-based powders for instant beverages.     

Inhibitory effects of Chrysanthemum species extracts on formation of advanced glycation end products

The corolla of Chrysanthemum species (C.morifolium R. and C.indicum L.) has long been used to treat eye and inflammatory disease. However, little is known about the antiglycation properties of Chrysanthemum species. Our study sought to characterise their activity against the formation of advanced glycation end products (AGEs) in glycation model reactions. In BSA/glucose (fructose) systems, both Chrysanthemum species strongly inhibited the formation of AGEs and N^ε-(carboxymethyl)lysine (CML). C.morifolium R., not C.indicum L., also acted to inhibit the formation of fluorescent AGEs, including pentosidine. This difference correlated with the values of polyphenol and flavonoid components. We characterised the active components in these plants by liquid chromatography-diode array detector-atmospheric pressure chemical ionisation/mass spectrometry, which showed that C. morifolium R. contains large amounts of chlorogenic acid, flavonoid glucoside varieties, and apigenin, while C.indicum L. contains large amounts of caffeic acid, luteolin, and kaempferol. Our findings raise hopes for the successful treatment of pathogenesis in conditions associated with diabetic complications and aging.     

Inhibitory effects of microalgal extracts on the formation of advanced glycation endproducts (AGEs)

The antiglycative activities of 20 microalgae at different growth phases were evaluated for the first time. In a bovine serum albumin (BSA)-glucose system, ethyl acetate fractions of green microalgae Chlorella and diatom Nitzschia laevis exhibited the highest inhibitory effects against the formation of total advanced glycation endproducts (AGEs) (inhibition rates: 81.76–88.02% and 91.68%) at the concentration of 500 ppm. Such abilities were higher than the effect of 1 mM aminoguanidine (AG) solution (inhibition rate: 80.51%), a commonly used inhibitor of glycation process. In addition to total AGEs, these fractions were also found to be effective in the blockage of the formation of two specific AGEs, pentosidine and N^ε-Carboxymethyllysine (CML). Different from many other plant species, AGE inhibitory abilities of selected microalgae were not due to the presence of phenolic compounds. HPLC and gas chromatography (GC) analysis revealed that carotenoids in Chlorella and unsaturated fatty acids, mainly of linoleic acid, arachidonic acid and eicosapentaenoic acid in Nitzschia laevis contributed to their strong antiglycative capacities.     

Inhibitory effect of polysaccharides from pumpkin on advanced glycation end-products formation and aldose reductase activity

Inhibitors of advanced glycation end-products formation and aldose reductase have been considered to be potential treatment of diabetic complications. This study investigated the abilities of polysaccharides extracted from pumpkin (PPs) to inhibit the formation of advanced glycation end-products and aldose reductase. The results showed that the inhibitory effects of PPs on the formation of advanced glycation end-products were higher than 50%, at 200 μg/ml, stronger than the positive control aminoguanidine, and the inhibitory effects of PPs on aldose reductase were higher than 58%, at 500 μg/ml, but not as potent as the positive control epalrestat. The result of this work suggests that pumpkin polysaccharides displayed therapeutic potential in the prevention and treatment of diabetic complications.     

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。     

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。     

食品中晚期糖基化终产物的研究进展

晚期糖基化终产物(advanced glycation end products,AGEs)被认为和氧化应激、多种慢性疾病以及人体衰老等具有密切关系,近年来成为医药和健康领域的研究热点,但在食品领域研究相对较少。事实上,食物由于不同的加工处理方法和存放条件,可能会产生AGEs;若长期摄入AGEs可能增加体内的AGEs水平从而对人体造成危害,对食品中AGEs的研究已引起食品领域科学家的关注。文中主要对食品中AGEs的生成机理、主要种类、检测方法、对人体的影响,以及控制方法等几方面进行综述。     

Inhibition of aflatoxin formation by some spices

The effects of black pepper, cinnamon, peppermint, cumin, ginger and clove on growth and aflatoxin formation of Aspergillus flavus were studied in rice powdercorn steep (RC) medium. The effects of the first five spices were judged to be inhibition of aflatoxin formation rather than of mycelial growth. Clove completely inhibited both mycelial growth and aflatoxin formation at a concentration above 0.1%. No aflatoxin was produced when cumin and mint levels of 5% and 10% were used. Black pepper and ginger levels of 10% decreased aflatoxin formation by 100%. Higher concentrations of cinnamon, mint, cumin and ginger stimulated mycelial growth.     

Inhibitory effect of mung bean extract and its constituents vitexin and isovitexin on the formation of advanced glycation endproducts

The anti-glycation activity of four kinds of beans including mung bean, black bean, soybean and cowpea were evaluated. Aqueous alcohol extract of mung bean exhibited the strongest inhibitory activity against the formation of fluorescent advanced glycation endproducts (AGEs) in a bovine serum albumin (BSA)-glucose model, and the inhibitory activities of extracts of the four beans were found to be highly correlated with their total phenolic contents (R² = 0.95). Subsequent HPLC analysis of mung bean extract revealed two major phenolics which were purified and identified as vitexin and isovitexin by spectral methods. In the anti-glycation assays, both vitexin and isovitexin showed significant inhibitory activities against the formation of AGEs induced by glucose or methylglyoxal with efficacies of over 85% at 100 μM. In another assay, vitexin and isovitexin failed to directly trap reactive carbonyl species, such as methylglyoxal, suggesting that their anti-glycation activities may mainly be due to their free radical scavenging capacity.     

紫苏叶提取物对美拉德体系晚期糖基化终末产物生成的抑制作用研究

目的 探究紫苏叶提取物(Perilla frutescens leaf extract,PLE)对美拉德体系晚期糖基化终末产物(advanced glycation end-products, AGEs)的抑制作用。方法 通过构建葡萄糖-赖氨酸模型体系,利用液相色谱-串联质谱法探究其在加热过程中PLE对N^ε-羧甲基赖氨酸[N^ε-(1-carboxymethyl)-L-lysine,CML]、N^ε-羧乙基赖氨酸[N^ε-(1-carboxyethyl)-L-lysine, CEL]和吡咯素(pyrraline, Pyr) 3种AGEs的抑制作用,同时通过评价PLE的抗氧化性、测定PLE对α-二羰基化合物抑制率,以探讨PLE对AGEs的可能抑制途径。结果 PLE对AGEs的生成具有显著的抑制作用,其抑制率与PLE的添加浓度成正比,当添加量为2.0 mg/mL时,对CML、CEL和Pyr的抑制率分别为47.23%、29.59%和37.77%。PLE中的主要活性物质为迷迭香酸、芹菜素-7-O-二葡萄糖苷和野黄...     

杏仁种皮黑色素抑制晚期糖基化末端产物(AGEs)的研究

建立牛血清蛋白-葡萄糖(BSA-Glucose)、牛血清蛋白-果糖(BSA-Fructose)和牛血清蛋白-丙酮醛(BSA-Methylglyoxal)的美拉德模拟反应体系,在体系中添加不同浓度的杏仁种皮黑色素,氨基胍(AG)作为阳性对照,37℃下反应,以荧光强度(Ex=370 nm,Em=440 nm)表示晚期糖基化末端产物(AGEs)含量,分析BSA-Glucose体系中蛋白质巯基、羰基含量变化,通过反相高效液相色谱/二极管阵列法(RP-HPLC-DAD)分析杏仁种皮黑色素对丙酮醛(Methylglyoxal,MGO)的清除效果。结果表明,杏仁种皮黑色素对BSAGlucose、BSA-Fructose、BSA-Methylglyoxal体系中AGEs的形成均有显著的抑制作用(P<0.05),抑制率最高分别达到73.81%、42.22%、38.57%。杏仁种皮黑色素能显著升高BSA-Glucose中蛋白质巯基含量(P<0.05),对MGO也具有清除作用,清除率随着时间的延长而升高,当反应24 h时,清除率达到最高,为63.54%。     

Detection of DNA-bound advanced glycation end-products by immunoaffinity chromatography coupled to HPLC-diode array detection

Sugars and sugar degradation products are formed during food processing, but also endogenously in vivo. In vitro, nucleosides and DNA react readily with these carbonyl compounds during the formation of the two diastereomers of N(2)-carboxyethyl-2'-deoxyguanosine (CEdG(A,B)), leading to a loss of DNA integrity. Only little is known about DNA glycation in vivo and about the influence of nutrition on CEdG formation. In this study, we developed a sensitive method to analyze DNA glycation by HPLC. For this purpose, immunoaffinity chromatography (IAC) using a polyclonal antibody against N(2)-carboxyethylguanine (CEguanine) was coupled to HPLC-DAD. In some samples, peak identity was confirmed by LC-MS/MS. The recovery of CEguanine from the IAC columns was 52.5% +/- 3.6 (n = 4). Thus, it was possible for the first time to detect CEdG(A,B), N(2)-carboxyethylguanosine (CEG(A,B)), and CEguanine in 11 human urine samples. However, due to imprecision of IAC, valid quantification of the adducts could not be achieved. Furthermore, CEdG was also detected in the DNA of cultured human smooth muscle cells (SMCs) and bovine aorta endothelium cells (BAECs). In BAECs, CEdG(A,B) were found by HPLC-DAD and LC-MS/MS after immunoaffinity purification, whereas in SMCs DNA-advanced glycation end-products were only detected with the more sensitive LC-MS/MS method.     

Investigation of pathways of advanced glycation end-products accumulation in macrophages

Advanced glycation end-products (AGE) play a role in the pathogenesis of several diseases, including diabetic complications and atherosclerosis. In atherosclerotic lesions of human aortas, AGE are localized in the extracellular matrix and intracellularly in foam cells. Two interpretations are possible for AGE accumulation inside macrophages, one is endocytic uptake of extracellular AGE-proteins by scavenger receptors; the other is intracellular AGE formation inside the macrophages. In the present study, we determined the pathways involved in AGE accumulation inside macrophages. RAW 264.7 cells, a murine macrophage cell line, incubated with BSA and 1600 mM glucose for 40 weeks, recognized heavily modified AGE- BSA. In contrast, the cells showed no ligand activity for mildly modified AGE-BSA, prepared by incubating BSA with 50 mM glucose for 24 weeks. Nepsilon-(carboxymethyl)lysine (CML)-modified proteins of about 65 kDa were detected in human monocyte-derived macrophages incubated for 7 days with 30 mM glucose and phorbol myristate acetate. Furthermore, CML was generated when glycated protein was incubated with hypochloric acid. Taken together, our results indicate that AGE detected inside foam cells in atherosclerotic lesions are generated intracellularly rather than representing endocytic uptake of extracellular AGE-proteins by scavenger receptors.     

山奈、白芷和香叶对猪肉加热过程中晚期糖化终末产物含量的影响

采用超高效液相色谱—串联质谱联用仪结合羧甲基赖氨酸(Nε-carboxymethyllysine,CML)和羧乙基赖氨酸(Nε-carboxyethyllysine,CEL)的同位素内标物作为AGEs的分析方法,研究了山奈、白芷和香叶3种食用香料的添加以及加热(100℃,5～120 min)对猪肉中结合态CML和CEL含量的影响。研究表明:加热对猪肉中AGEs的产生有促进作用,且AGEs的含量随着加热时间的延长而增加,经120min加热后的猪肉中CML和CEL的含量约为生肉的5～8倍,分别达到(35.60±2.20)～(40.68±5.66)mg/kg(CML)和(13.32±1.49)～(16.85±2.44)mg/kg(CEL)。在0～40min的加热时间过程中,加入或未加入香料的猪肉中CML[R~2=0.971～0.996;k=0.355～0.590mg/(kg·min)]和CEL[R~2=0.942～0.997;k=0.150～0.368mg/(kg·min)]的形成均符合零级反应动力学方程。香料的添加对于猪肉在加热过程中AGEs形成的影响因香料的种类、加热时间、肉的批次的不同而不同,总体来说,香料对猪肉加热过程中CML的形成影响较小,但是对CEL的形成有一定的促进作用,尤其是加热5 min处理的肉样,其CEL含量增加13%～61%。