Effect of flavonoids on learning,memory and neurocognitive performance: relevance and potential implications for Alzheimer's disease pathophysiology

Recent evidence has indicated that a group of plant‐derived compounds known as flavonoids may exert particularly powerful actions on mammalian cognition and may reverse age‐related declines in memory and learning. In addition, growing evidence is also suggestive that flavonoids may delay the development of Alzheimer's disease‐like pathology, suggestive of potential dietary strategies in dementia. Although these low‐molecular‐weight phytochemicals are absorbed to only a limited degree, they have been found to counteract age‐related cognitive declines possibly via their ability to interact with the cellular and molecular architecture of the brain responsible for memory. However, the majority of the research has been carried out at rather supraphysiological concentrations and only a few studies have investigated the neuromodulatory effects of physiologically attainable flavonoid concentrations. This review will summarize the evidence for the effects of flavonoids and their metabolites in age‐related cognitive decline and Alzheimer's disease. Mechanisms of actions will be discussed and include those activating signalling pathways critical in controlling synaptic plasticity, reducing neuroinflammation and inducing vascular effects potentially capable of causing new nerve cell growth in the hippocampus. Altogether, these processes are known to be important in maintaining optimal neuronal function, to limit neurodegeneration and to prevent or reverse age‐dependent deteriorations in cognitive performance. © 2013 Society of Chemical Industry     

Effect of Processed Onions on the Plasma Concentration of Quercetin in Rats and Humans

Onion is a major dietary source of the bioactive flavonoid, quercetin. Quercetin aglycone (QA) is exclusively distributed in the onion peel, although quercetin‐4′‐β‐O‐glucoside (Q4′G) is present in both the peel and the bulb, and quercetin‐3,4′‐β‐O‐diglucoside (Q3,4′diG) is present only the bulb. The bioavailability of flavonoids from fruits and vegetables is frequently affected by the manufacturing process and related conditions. The present study aimed to estimate the effect of food processing on the bioavailability of onion QA and its glucosides, Q4′G and Q3,4′diG, provided through the consumption of onion products. Rats were fed onion peel and onion bulb products‐mixed meal or pure QA/Q4′G+Q3,4′diG‐mixed meal at 5 mg QA equivalent/kg body weight. A comparison of the blood plasma concentrations strongly suggested that quercetin glucosides (Q4′G and Q3,4′diG) are superior or at least equal to QA in their bioavailability, when each purified compound is mixed with the meal. The intake of a peel powder‐containing meal provided a significantly higher increase of plasma quercetin concentration than the peel extract, bulb powder, bulb extract, and bulb sauté containing meals at each period tested. A human ingestion study confirmed the superiority of onion peel powder to onion peel extract. The difference of log P for QA between peel powder and peel extract indicated that a food matrix improves the bioavailability of QA in onion peel products. These results demonstrated that the bioavailability of quercetin provided by not the onion bulb but the onion peel is significantly affected by food processing.     

槲皮素对酪氨酸酶的抑制作用与分子机理

本文以L-多巴为底物,采用酶抑制动力学法研究了槲皮素对酪氨酸酶的抑制作用大小及类型,并采用荧光光谱技术分析其与酪氨酸酶的猝灭作用类型、结合位点、作用力类型。在此基础上,进一步利用柔性分子对接技术分析槲皮素对酪氨酸酶的抑制机理。结果表明,槲皮素对酪氨酸酶具有抑制作用,抑制常数KI为36 m M,以竞争性抑制剂形式抑制酪氨酸酶活性,是一种可逆性抑制剂;槲皮素以1:1比例通过氢键和疏水作用力结合于酪氨酸酶活性中心,且对酪氨酸酶的荧光产生静态淬灭作用,具有氢键及疏水作用力;分子对接结果验证了以上实验结论:槲皮素占据了酪氨酸酶活性中心,且与活性中心部位的Asn260和Gly62残基形成了强烈的氢键作用,同时伴有疏水作用共同稳定复合物的结构。     

白皮杉醇对阿尔茨海默病小鼠认知功能的改善作用

研究白皮杉醇对阿尔茨海默病(Alzheimer''s disease, AD)小鼠认知障碍的改善作用。取72只雄性昆明小鼠,随机分为6组,每组12只,即正常对照组、模型对照组、阳性对照组、白皮杉醇低、中、高剂量干预组。采用AlCl₃和D-半乳糖联合诱导的方法连续干预70d,建立阿尔茨海默病小鼠模型。在造模35d开始用白皮杉醇连续干预,5周后通过Morris水迷宫实验评价小鼠的空间学习记忆能力,通过酶联免疫法(ELISA)检测小鼠海马体中Aβ1-42及TNF-α蛋白表达水平、小鼠血清超氧化物歧化酶(SOD)活力、谷胱甘肽过氧化物酶(GSH-Px)和丙二醛(MDA)含量并结合相对脏器指数分析白皮杉醇对AD小鼠的保护效果。研究发现,与正常组比较,模型对照组小鼠逃避潜伏期显著性增加,记忆能力显著性降低,而白皮杉醇可有效提高模型小鼠认知行为和记忆能力(P<0.01);此外,与正常组比较,模型对照组小鼠脑组织中Aβ1-42水平及炎症因子TNF-α表达水平明显升高,小胶质细胞活化明显增加,而白皮杉醇干预组小鼠Aβ1-42、TNF-α及胶质细胞活化水平均显著降低(P<0.01)。进一步研究表明,白皮杉醇能有效提升小鼠血清SOD活力和GSH-Px水平,降低MDA含量,减轻氧化应激损伤。研究结果表明,白皮杉醇可以通过降低脑组织氧化应激及神经炎症反应,减少海马中β淀粉样蛋白的生成来改善阿尔茨海默病小鼠的认知功能障碍。     

槲皮素抑制黄曲霉毒素产生的机制初探

研究发现茶叶中的茶多酚单体普遍具有抑制黄曲霉毒素B1(AFB1)产生的活性,而槲皮素的抑毒活性要高于等浓度下儿茶素类茶多酚。为了解槲皮素抑制黄曲霉毒素产生的分子机制,对黄曲霉菌的抗氧化系统、毒素产生的相关基因进行了分析。试验结果显示槲皮素处理能后降低黄曲霉菌内的ROS水平,降低MDA含量。RT-PCR结果证实槲皮素能够激活抗氧化系统转录因子Yap1,导致黄曲霉体内的抗氧化酶系统活性的增加,POD、CAT、SOD都得到了显著的提高,这很可能是槲皮素抑制AFB1产生的关键因素;槲皮素能同时下调AflR与AflS的表达,而AflS能够通过结合AflR调控产毒基因的表达,这很可能是槲皮素抑制AFB1产生的核心分子机制,这种机制也与其激活抗氧化系统缓解菌体内氧化胁迫的作用相对应。以上结果表明槲皮素作为一种高效的黄曲霉毒素合成抑制剂,将对提高食品安全保障具有较高的应用价值。     

槲皮素及其递送体系的研究进展

槲皮素是一种广泛存在于食品中的生物活性物质,具有抗氧化、抗炎症、抗肿瘤、预防心血管疾病等功效。为解决其水溶性差、稳定性低等问题,前人已围绕着槲皮素的递送体系展开了大量研究。为此,本文结合国内外研究进展,从槲皮素的理化特性、生物活性、稳定性、体内代谢及其递送体系的角度进行了综述。并在此基础上对槲皮素及其递送体系的安全性进行了介绍,旨在为拓展其在食品领域的应用提供相关理论依据。     

L-Arginine and Nitric Oxide in CNS Function and Neurodegenerative Diseases

One of the main functions of L-arginine (ARG) is the synthesis of nitric oxide (NO). NO is an important regulator of physiological processes in the central nervous system (CNS). NO promotes optimal cerebral blood flow, consolidates memory processes, facilitates long-term potentiation, maintains sleep-wake cycles, and assists in normal olfaction. However, at pathological levels, NO adversely affects brain function producing nitroxidative stress and promoting development of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and other disorders of the CNS. This review summarizes current knowledge of the role of NO in the CNS and the role of diet in regulating the levels of NO.     

6种茶叶提取物的乙酰胆碱酯酶抑制活性研究

目的 研究6种茶叶提取物的乙酰胆碱酯酶抑制活性。方法 采用改良的Ellman酶促反应来检测乙酰胆碱酯酶的活性, 以乙酰胆碱酯酶的活性为指标, 计算乙酰胆碱酯酶抑制率。结果 6种茶叶均具有不同程度的乙酰胆碱酯酶抑制活性。当萃取物浓度为1 mg/mL时, 宁红茶表现出很强的乙酰胆碱酯酶抑制活性, 平均抑制率高达64.41%。云台山毛尖和靖安白茶抑制率较高均在50%以上, 分别为56.27%和54.42%。狗牯脑、庐山云雾茶和铁观音抑制率分别为34.53%、29.62%、21.47%。当萃取物浓度下降为0.1 mg/mL时, 萃取物抑制活性有明显下降, 6种茶的平均抑制率均小于30%。结论 6种茶叶中云台山毛尖、宁红茶和靖安白茶有较强的乙酰胆碱酯酶抑制活性, 可为开发相关的功能性食品提供参考。     

载体油对槲皮素纳米乳液理化稳定性和生物利用度的影响

研究载体油种类和体积分数对纳米乳液稳定性和槲皮素生物利用度的影响.以中链甘油三酯(medium-chain triglyceride,MCT)和长链甘油三酯(long-chain triglyceride,LCT)为油相,梨小豆蛋白为乳化剂制备槲皮素负载型纳米乳液.通过光散射粒径分析、Zeta电位、物理稳定性、游离脂肪...     

食品包装材料对食品安全性的影响及控制措施

介绍了食品包装材料的种类及污染的来源,并提出了一些控制措施来降低包装材料可能产生的污染。     

槲皮素对肥胖母鼠后代生长发育的影响

目的：研究孕、哺乳期给予槲皮素对肥胖母鼠后代生理和神经发育的影响。方法：建立营养性肥胖雌性SD大鼠模型,交配受孕,随机分成5组,每组16只孕鼠,整个实验期进食高脂饲料,并分别以0、50、100、200mg/kg剂量的槲皮素灌胃;以16只正常体质量孕鼠作为空白对照,整个实验期喂食基础饲料并以溶剂灌胃。记录仔鼠出生体质量,并观察主要生理和神经发育指标。结果：高脂对照组后代出生体质量显著高于空白对照组,随槲皮素干预剂量增大,出生体质量逐渐降低,接近空白对照水平。该作用持续到断乳。生理发育：高脂对照组雄性仔鼠睾丸下降迟于空白对照组,槲皮素能在一定程度上逆转此影响,200mg/kg效果最显著;神经发育：200mg/kg组的平面翻正、悬崖回避反射达标时间明显早于空白对照组和高脂对照组。结论：肥胖孕鼠后代出生体质量显著增加,而孕期槲皮素干预可有效逆转新生仔鼠体质量,控制其哺乳期体质量过快增长。一定剂量的槲皮素能够有效逆转孕期肥胖造成的雄性后代睾丸下降延迟,并能够促进后代特定神经反射的形成。     

食品添加剂对薯类食品品质影响的研究进展

随着我国"马铃薯主食化"战略的提出,薯类食品的研究开发受到重视。薯类淀粉支链淀粉含量和直链淀粉聚合度高,蛋白含量低,不易形成网络结构。添加薯类淀粉会导致食品的黏度增加,严重影响外观及口感,是薯类食品生产应用中的一个大问题。食品添加剂可以有效解决产品的感官品质差等问题,是近年研究的热点。分析总结了不同种类食品添加剂对薯类食品品质的影响,并对薯类食品未来的科学研究方向进行展望,为食品添加剂在薯类食品中的应用提供理论基础和指导意义。     

Bioavailability of Quercetin in Humans with a Focus on Interindividual Variation

After consumption of plant‐derived foods or beverages, dietary polyphenols such as quercetin are absorbed in the small intestine and metabolized by the body, or they are subject to catabolism by the gut microbiota followed by absorption of the resulting products by the colon. The resulting compounds are bioavailable, circulate in the blood as conjugates with glucuronide, methyl, or sulfate groups attached, and they are eventually excreted in the urine. In this review, the various conjugates from different intervention studies are summarized and discussed. In addition, the substantial variation between different individuals in the measured quercetin bioavailability parameters is assessed in detail by examining published human intervention studies where sources of quercetin have been consumed in the form of food, beverages, or supplements. It is apparent that most reported studies have examined quercetin and/or metabolites in urine and plasma from a relatively small number of volunteers. Despite this limitation, it is evident that there is less interindividual variation in metabolites which are derived from absorption in the small intestine compared to catabolites derived from the action of microbiota in the colon. There is also some evidence that a high absorber of intact quercetin conjugates could be a low absorber of microbiota‐catalyzed phenolics, and vice versa. From the studies reported so far, the reasons or causes of the interindividual differences are not clear, but, based on the known metabolic pathways, it is predicted that dietary history, genetic polymorphisms, and variations in gut microbiota metabolism would play significant roles. In conclusion, quercetin bioavailability is subject to substantial variation between individuals, and further work is required to establish if this contributes to interindividual differences in biological responses.     

槲皮素和芦丁对猪肉肌原纤维蛋白结构的影响

采用羟自由基氧化体系,探讨槲皮素和芦丁(0、0.1、0.2、1、2 mmol/L)作为抗氧化剂对猪肉肌原纤维蛋白氨基酸侧链结构的影响。结果表明,随着芦丁含量的增加,蛋白质游离巯基含量呈增加趋势,1、2 mmol/L芦丁组与对照组相比显著升高(p<0.05)。随着槲皮素和芦丁含量从0增加到2 mmol/L,表面疏水性呈增加趋势,而二聚酪氨酸含量和内源色氨酸荧光强度都呈下降趋势。在氧化体系中添加槲皮素和芦丁,抑制了肌原纤维蛋白的氧化。     

新食品经济的发展趋势及其对食品产业的影响

随着信息与通信技术的发展,其应用不断扩展到其它领域,食品行业的应用改变了传统的商业经营模式,催生了"新食品经济"。新食品经济以市场为导向,以消费者为中心,以信息网络为媒介,缩减了信息交换成本,对食品行业及其相关政策法规产生了重大影响,推动食品行业向高技术、高质量、高效率发展。