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.     

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.     

早期给予膳食槲皮素对大鼠母代生殖及其子代生长发育的影响

目的:研究早期给予槲皮素对母鼠生殖及其子代发育的影响。方法:孕鼠随机分为4组:空白对照组、槲皮素低、中、高剂量组(从孕0d至断乳21d灌胃给予槲皮素,剂量分别为16、160、480mg/(kg.d))。定期检测母鼠和仔鼠的生长指标、繁殖能力、幼仔存活及幼仔肛殖距(AGD),产后第21天处死母鼠和仔鼠,计算母鼠和幼仔脏器指数。结果:与空白对照组相比,槲皮素组对母鼠体质量、繁殖能力、幼仔存活率没有影响;槲皮素低、中剂量组中雄性仔鼠AGD和体质量显著降低;槲皮素组对雌性仔鼠AGD和体质量没有影响;槲皮素高剂量组降低母鼠和雄性仔鼠的脾脏指数,中剂量组增加雌性仔鼠肾脏指数。结论:槲皮素具有雌激素及抗雌激素作用,对雄性仔鼠影响较大,无生殖与发育毒性。     

从洋葱中提取栎皮酮的研究

从洋葱中提取天然的食品抗氧化剂——栎皮酮，经正交实验确定了最佳的工艺条件为：提取液为0．03mol／L的NaOH溶液，提取温度为60℃，料液比为1：2，提取时问为120min，酸沉终点pH为2。通过测定抑制亚油酸氧化百分率的实验表明，所提取的栎皮酮有较好的抗氧化能力。     

槲皮素对脂质代谢的影响研究进展

槲皮素是最常见的黄酮类化合物之一,广泛存在于水果、蔬菜之中,具有多种生物学功能。近年来的体内外试验研究结果显示,槲皮素对脂质代谢有调节作用,具体表现为抑制胆固醇生物合成、降低甘油三酯、游离脂肪酸、低密度脂蛋白与极低密度脂蛋白水平,升高高密度脂蛋白水平,防止脂质过氧化和脂质蓄积。     

槲皮素功能特性研究概况

槲皮素是许多中草药中所含一种黄酮类化合物,具有很高生物活性;该文综述槲皮素提取方法、功能价值及其应用。     

多孔硅/槲皮素复合材料的制备及抗氧化性能

该研究以正硅酸乙酯为硅源,用改良的Stöber法制备了多孔二氧化硅微球,并用3-氨丙基乙氧基硅对其进行氨基功能化,成功将其与槲皮素复合,制备了多孔硅/槲皮素复合纳米材料。研究表明,多孔二氧化硅微球的比表面积、比孔容和平均孔径分别为1530.63 m2/g、0.92 cm3/g和2.40 nm。对比实验证明每毫克氨基功能化的二氧化硅微球能够负载0.09 mg槲皮素,是功能化之前的2.25倍。原因有两个,一是因为氨基是亲水性基团,氨基化的二氧化硅微球具有更好的水分散性;另一方面,氨基可与槲皮素分子中的羟基形成氢键,使得氨基化的二氧化硅微球更容易与槲皮素复合。用DPPH法表征了该复合纳米材料的自由基清除率。结果表明,在相同条件下,多孔硅/槲皮素复合纳米材料和纯槲皮素的自由基清除率分别为48.44%和32.81%,这说明与多孔二氧化硅微球复合可以提高槲皮素的抗氧化活性,可能与多孔二氧化硅微球对槲皮素的保护作用有关。     

玉米醇溶蛋白/阿拉伯胶负载槲皮素纳米颗粒制备

以玉米醇溶蛋白为载体,阿拉伯胶为稳定剂,反溶剂法制备负载槲皮素的玉米醇溶蛋白-阿拉伯胶纳米颗粒。考察阿拉伯胶浓度、槲皮素与玉米醇溶蛋白/阿拉伯胶质量比、p H、盐离子强度等因素对纳米颗粒稳定性的影响。结果表明,阿拉伯胶质量浓度50 g/L,制得粒径201.5 nm,多分散指数0.35,电位-31.5 mV的稳定玉米醇溶蛋白/阿拉伯胶载体;槲皮素/玉米醇溶蛋白-阿拉伯胶质量比1︰10时,粒径、颗粒分散性、ζ-电位均在稳定范围内,且包封率和负载率能达到84.3%和13.96%以上;盐离子浓度高于30 mmol/L时,玉米醇溶蛋白与阿拉伯胶之间的静电作用减弱,纳米颗粒体系不稳定,发生聚集;纳米颗粒能经历广泛pH变化,不发生聚集,大幅提高了包埋对象的生物利用度。     

乌饭树树叶中槲皮素的提取分离与鉴定

乌饭树是一种具有一定营养价值和保健功能的食品资源，其保健功能在许多资料中都有记载，但其主要功能性成分尚不清楚，作者对其树叶中色素的成分进行了初步分析，首次从中分离鉴定了槲皮素成分。     

槲皮素微胶囊的贮藏稳定性及抗氧化活性

以壳聚糖、海藻酸钠为壁材,采用复凝聚法制备槲皮素微胶囊,通过结构表征、加速贮藏释放和体外模拟消化对槲皮素微胶囊的稳定性及抗氧化活性进行综合评价。红外光谱分析表明,槲皮素成功包埋在壳聚糖-海藻酸钠复合物中;扫描电子显微镜显示微胶囊表面疏松多孔,呈不规则形状;X-射线衍射分析表明,槲皮素在微胶囊中的结晶性质没有发生变化;微胶囊能提高槲皮素在光照、有氧、温度50℃、相对湿度84%条件下的稳定性,经过体外模拟胃肠消化后,表现出较好的抗氧化活性。     

茶叶中槲皮素单体的分离与制备

以体积分数95%乙醇作为洗脱溶剂,通过Sephadex LH-20柱层析从茶多酚中分离槲皮素,粗品得率为7.82%,HPLC检测纯度为20.40%。槲皮素粗品3.00g经沉淀、冷冻干燥后得178.00mg,HPLC检测纯度为98.89%,纯品得率为5.93%,结构由核磁共振氢谱和碳谱得以确证。     

槲皮素对高脂饮食诱导肥胖小鼠结肠炎症的改善作用

探讨槲皮素干预对高脂饮食诱导肥胖小鼠结肠组织炎症的改善作用及机制。将30只雄性C57BL/6J小鼠随机分为3组:低脂对照组(low-fat diet, LF)、高脂喂养组(high-fat diet,HF)、高脂喂养+槲皮素干预组(50 mg/kg·BW,HF+Q)。槲皮素干预的给药方式为灌胃给予,每天灌胃1次,持续20周。采用苏木精-伊红染色观察结肠组织形态结构,ELISA试剂盒检测肠内容物中脂多糖(LPS)含量,Real-time PCR和Western Blotting测定结肠中细胞因子[白介素-1β(IL-1β)、白介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)]水平,以及检测槲皮素干预对TLR4/NF-κβ信号通路的影响。槲皮素干预显著减少肥胖小鼠的体重增加(p0.05),修复结肠组织形态学上的损伤,能够显著降低LPS含量至5.04 ng/mL(vs HF组:7.01 ng/mL,p0.05),分别抑制结肠组织中炎性因子TNF-α(39.04%)、IL-1β(17.73%)和IL-6(25.47%)的蛋白表达,以及抑制TLR4/NF-κβ信号通路的激活。结论提示,槲皮素对肥胖小鼠结肠组织炎症具有改善作用,减少炎性因子的表达,其作用机制可能和抑制TLR4/NF-κβ信号通路的激活相关。     

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。     

Effects of Onion Quercetin on Oxidative Stability of Cook-chill Chicken in Vacuum-sealed Containers

The effects of onion quercetin were evaluated in relation to the storage stability of cooked dark chicken meat in retarding post-cooking oxidative changes. Autooxidation was followed using the 2-thiobarbituric acid (TBA) test. Dried onion flesh at 1.6% (w/w), typical for common cooking, reduced (P < 0.001) the TBA value in cooked chicken during refrigerated storage, when mixed before processing. The NaCl did not act as a prooxidant. The antioxidant effect (by TBA) of onion mixed with chicken meat prior to processing was equivalent to that of its measured quercetin content, quantified by high-performance liquid chromatography.     

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。     

槲皮素对胰蛋白酶活性的影响

通过测定槲皮素对胰蛋白酶催化活性、催化反应动力学以及内源荧光光谱的影响,对槲皮素和胰蛋白酶相互作用特性进行研究.结果表明:槲皮素对胰蛋白酶催化活性有明显的抑制作用,当槲皮素与胰蛋白酶的摩尔比为44∶1,在37℃反应10min,抑制率达到32.5％;反应时间对两者的作用影响并不明显;槲皮素对胰蛋白酶催化活性的抑制作用属于可逆的竞争性抑制;槲皮素可使胰蛋白酶的内源荧光发生猝灭现象,猝灭常数Kq是4.7415×1012 (mol/L)1·S-1,猝灭类型为静态猝灭,结合位点数N为0.9206.     

均匀设计优化制备槲皮素固体脂质纳米粒

目的制备槲皮素固体脂质纳米粒。方法采用高温乳化-低温固化法制备槲皮素固体脂质纳米粒,以包封率为考察指标,均匀设计法优化处方与制备工艺。结果按最优工艺条件制得的纳米粒均匀圆整,粒径为(203±75)nm,包封率为48.5%。结论优选的槲皮素固体脂质纳米粒制备工艺稳定可行。     

芦丁、槲皮素对α-淀粉酶抑制活性研究

以α-淀粉酶为评价指标,探讨了芦丁和槲皮素的辅助降血糖功能。研究结果芦丁和槲皮素对α-淀粉酶抑制均呈阳性,表明芦丁和槲皮素都具有辅助降血糖的功能。芦丁溶液、槲皮素溶液和阿卡波糖对α-淀粉酶的半抑制浓度分别为0.258mg/mL、0.233mg/mL、0.095mg/mL。芦丁、槲皮素、阿卡波糖对α-淀粉酶的抑制作用大小顺序为:阿卡波糖>槲皮素>芦丁。