河蚬抗氧化肽-锌螯合物抗氧化活性的研究

研究了河蚬抗氧化肽-锌螯合物体外抗氧化能力,以Vc为阳性对照,选用·OH清除率、DPPH·清除率、ABTS~+·清除率、O_2~-·清除率、还原力及对油脂的抗氧化性6种方法,并将其与河蚬抗氧化肽进行比较。结果表明:河蚬抗氧化肽-锌螯合物对4种自由基有一定的清除能力,对·OH、DPPH·、O_2~-·和ABTS~+·的IC_(50)分别为1.44、1.93、3.20 mg/mL和2.26 mg/mL,具有一定的还原力,对猪油及芝麻油的氧化均有抑制效果,且河蚬抗氧化肽-锌螯合物的体外抗氧化活性高于河蚬抗氧化肽,为其在抗氧化活性方面的应用提供理论依据。     

锌离子螯合修饰河蚬抗氧化肽的工艺

确定锌离子螯合修饰河蚬抗氧化肽的最佳工艺条件。以螯合率为响应值,通过单因素试验和响应曲面分析方法优化河蚬抗氧化肽螯合锌的工艺参数,确定最优螯合工艺条件:pH 5.07,抗氧化肽与锌离子质量比2.18︰1,螯合时间46.50 min,螯合温度52.65℃。在最优工艺条件下,河蚬抗氧化肽螯合锌的螯合率为81.78%。     

酪蛋白GYLEQ抗氧化肽——钙螯合物的制备、表征及功能特性

目的:开发具有抗氧化活性和补钙功能的产品。方法:在固相法合成GYLEQ抗氧化肽的基础上,采用单因素和正交试验优化酪蛋白GYLEQ抗氧化肽与钙离子螯合反应条件,利用红外光谱和扫描电镜表征GYLEQ-Ca螯合物的结构,并分析GYLEQ-Ca螯合物体外抗氧化活性、模拟胃肠液中的持钙率以及对细胞活力的影响。结果:GYLEQ-Ca螯合反应最佳条件为螯合温度50℃,螯合时间40 min, pH 7.5,肽钙质量比4∶1,其中温度对螯合率的影响达到了极显著水平,pH和肽—钙质量比对螯合率的影响达到了显著水平。螯合后产物的红外波谱吸收峰与GYLEQ肽相比发生了改变,扫描电镜观察发现GYLEQ肽为颗粒状,而GYLEQ-Ca螯合物为黏连在一起的网状结构,表明GYLEQ肽与钙离子反应生成了新的化合物。GYLEQ-Ca螯合物的DPPH自由基、羟自由基清除率和还原力高于GYLEQ肽,GYLEQ-Ca螯合物在模拟肠液中持钙率维持在70%以上,且无细胞毒性。结论:GYLEQ-Ca螯合物具有较好的抗氧化活性和钙维持率。     

河蚬多肽螯合钙的制备和抗氧化活性分析

得到河蚬多肽螯合钙的最佳螯合工艺,并测定其抗氧化活性。考察螯合温度、时间、河蚬多肽与钙离子的质量比以及pH对螯合率的影响,根据响应面分析试验结果,得出最佳螯合工艺;并测定螯合前后的抗氧化活性。结果表明,在pH为8.0,河蚬多肽与钙离子的质量比为2.3∶1,螯合时间为39 min,螯合温度为40℃时,实际测得河蚬多肽螯合钙的螯合率为82.52%,预测值为83.63%;多肽螯合物对DPPH自由的清除能力增强。河蚬多肽螯合钙的制备为河蚬的开发利用提供了必要的理论基础。     

米糠肽-铁锌螯合物制备工艺研究

目的 研究米糠蛋白制备米糠肽-铁锌螯合物的工艺。方法 以米糠蛋白为原料,优化米糠肽-铁锌螯合物制备工艺。以亚铁离子与锌离子的螯合率和水解度为评价指标,考察蛋白酶种类、反应物质量比、温度、时间及pH值对米糠酶解产物铁锌螯合率的影响。在单因素试验的基础上,结合JMP软件进行定制试验设计,确定米糠肽-铁锌螯合物的制备工艺。结果 碱性蛋白酶较适宜制备米糠肽-铁锌螯合物,其最佳螯合工艺条件为时间70 min、温度70 oC、反应物质量比3:1、pH 5.0;在此条件下,其产物亚铁离子螯合率达到38.29%、锌离子螯合率达到57.2%,与预测值接近。结论 本研究采用米糠肽同时螯合铁锌2种金属离子,不仅可以充分吸收米糠肽的营养成分,提高消化率,发挥其降血压、降血脂、抗氧化等功能特性,还可以同时补铁、补锌,对人体具有积极作用。     

绿豆多肽锌螯合物的制备及其结构与体外消化的分析

为生产易被人体消化吸收的锌补充剂,提高绿豆的附加值,本实验将绿豆多肽与锌进行螯合,以螯合能力为指标,采用单因素与响应面结合的方法,对螯合工艺进行优化;运用傅里叶红外光谱、紫外光谱、扫描电镜、X-射线衍射等方法比较螯合前后结构的变化;并利用体外模拟胃肠道消化测定肽锌螯合物中锌离子的生物利用率。结果表明:制备肽锌螯合物的最佳条件为肽锌质量比6.20∶1、反应温度50℃、反应时间83 min、反应pH 6.3,在此条件下螯合率达到52.19 mg/g;光谱分析表明,多肽的氨基、羧基与酰胺基参与了反应;扫描电镜、X-射线衍射显示多肽与螯合物在表面微观结构和结晶程度上均有较大改变;体外模拟胃肠道消化研究表明肽锌螯合物中锌离子的溶解率和透析率均显著高于无机锌盐。实验综合表明生成了一种新型螯合物,且螯合物锌离子的生物利用率较高,具有潜在的应用意义。     

正交试验优化花生肽螯合锌的制备工艺

研究了花生蛋白水解物和锌离子制备肽锌螯合物的工艺条件,以螯合率为评价指标,考察肽与锌的质量比、反应pH、反应温度和反应时间对螯合反应的影响。在单因素试验基础上,采用4因素3水平正交法确定花生肽-锌螯合物的制备工艺。最佳工艺条件:花生肽-锌质量比4∶1、反应体系pH 6.0、反应温度50℃、反应时间40 min。在此条件下,锌的螯合率为57.04%。     

?微生物法制备松仁肽-锌螯合物及其抗氧化功能的研究

实验研究了微生物法制备松仁肽-锌螯合物及抗氧化性质,利用松仁粕为原料制作培养基,选用枯草芽孢杆菌(Bacillus subtilis)ls-45为发酵菌种,以硫酸锌为锌源,运用微生物法进行螯合,微生物将大分子的松仁蛋白分解为小分子肽的同时与锌离子螯合,以硫酸锌的添加量、发酵温度、发酵时间、pH 4个因素进行单因素实验和响应面实验对螯合工艺参数进行优化,以螯合率为指标,确定最佳的工艺参数为:硫酸锌添加量为0.6 g,时间为50.36 h,温度为38.46℃,pH值为7.41。得到最佳螯合率90.60%。通过体外抗氧化实验对松仁肽-锌螯合物、松仁肽、VC等物质的不同浓度进行DPPH自由基清除率、还原能力、羟自由基清除率等3个指标的测定,实验结果表明松仁肽-锌螯合物的抗氧化性均高于松仁肽,并随着质量浓度的增加而呈现量效关系,由此可以初步判断松仁肽-锌螯合物具有良好的抗氧化功能。     

宽体金线蛭多肽-锌螯合物的制备及其结构表征

以宽体金线蛭组织为蛋白源,用木瓜蛋白酶和风味蛋白酶组成的复合酶对宽体金线蛭组织进行酶解,然后将酶解得到的多肽与硫酸锌在不同条件下进行反应,经过硫化钠法定性测定,制备出一种多肽-锌螯合物。运用紫外、红外、荧光、X衍射分析技术对多肽和多肽-锌螯合物的结构进行初步研究分析。结果表明:反应体系pH、多肽与锌的质量比、多肽浓度对宽体金线蛭多肽与七水合硫酸锌的螯合反应具有重要影响;通过对多肽和多肽-锌螯合物的紫外、红外、荧光、X衍射图谱对比分析,发现两者的图谱明显改变,说明多肽加锌螯合后结构产生了显著变化;最后根据多肽与多肽-锌螯合物的红外光谱图和多肽金属螯合物的一些结构特性,推断出宽体金线蛭多肽-锌螯合物的一种可能结构。     

鲐鱼暗色肉肽锌螯合物的制备及结构表征

为生产易被人体消化吸收的锌补充剂,提高鲐鱼暗色肉的附加值,本研究将鲐鱼暗色肉寡肽与锌进行螯合。以鲐鱼暗色肉蛋白肽(相对分子质量小于3 000)为原料,采用超声法制备鲐鱼暗色肉肽螯合锌。以螯合得率和螯合率为指标,采用单因素与响应面结合的方法,对螯合工艺进行优化,并对螯合物进行氨基酸、能谱分析。结果表明,最佳螯合工艺条件为:螯合时间51 min、螯合温度72℃、肽锌质量比1∶2、肽质量分数5.35%、螯合pH值7.9时,在该工艺条件下测得肽锌螯合得率与螯合率分别为55.86%、65.12%,与模型预测值相符。本研究为锌螯合物的制备以及鲐鱼暗色肉的高值化利用提供了理论依据。     

美国红鱼鱼鳞制备多肽金属螯合物的工艺优化

本文研究并优化了以美国红鱼（Sciaenops ocellatus）鱼鳞为原料制备多肽及合成多肽金属螯合物的工艺条件。以美国红鱼鱼鳞为原料制备多肽,采用凝胶色谱分析多肽的分子量;利用水体系法合成多肽金属螯合物并采用EDTA络合滴定法测定金属螯合率;设计并利用L₉（34）正交试验优化了多肽金属螯合物工艺条件;利用红外光谱检测多肽和多肽金属螯合物,验证多肽与金属的结合。凝胶色谱分析获得多肽分子量在1~6 kDa左右,正交试验获得了多肽金属螯合物的制备工艺条件,即多肽锌螯合物的工艺条件为质量比2:1、pH5.5、温度55 ℃、时间60 min;多肽铜螯合物的工艺条件为质量比2:1、pH6.0、温度35 ℃、时间55 min,在该最佳螯合条件下制备的多肽锌、铜螯合物的螯合率分别为78.21%、91.24%。红外吸收光谱结果显示Zn2+、Cu2+与-NH₂结合成功,表明多肽锌、铜螯合物是新的物质。研究结果表明,该工艺条件下的螯合率明显提高,且富含金属离子、成本低廉、市场前景可观,有利于海洋水产加工副产物高值化应用,促进渔业加工产业的技术升级。     

河蚬多肽螯合亚铁的制备工艺研究

以河蚬肉为原料制备河蚬多肽,探讨河蚬多肽与亚铁离子螯合的最佳工艺条件。在单因素实验的基础上,采用响应面分析法对河蚬多肽螯合亚铁离子的工艺条件进行优化,确定最佳的螯合工艺条件为pH6.0,多肽与亚铁离子质量比1.5:1,螯合时间41 min,螯合温度31℃,螯合率预测值为82.40%,实测值为81.63%。红外光谱分析表明,多肽中的氨基和羧基均参与了螯合反应。本研究拓宽了河蚬的加工利用途径,并为多肽螯合亚铁的开发应用提供理论基础。     

Hepatoprotective peptides purified from Corbicula fluminea and its effect against ethanol-induced LO2 cells injury

This study was focused on the purification, identification and mechanism of hepatoprotective peptides from Corbicula fluminea by using Sephadex G-15 chromatography, UPLC–MS/MS, oxygen radical absorbance capacity (ORAC) assay, cell experiment and molecular docking. Six identified peptides were synthesised chemically and subjected to evaluate hepatoprotective effect. ORAC value and hepaprotective effect against ethanol-induced LO2 cell injury in vitro were determined. The results showed that Tyr-Phe-Leu-Pro (YP-4) and Leu-Val-Tyr-Pro (LP-4) exhibited the strongest antioxidant activity and significantly increased the viability of ethanol-injured LO2 cells. These two peptides significantly reduced ROS levels and efficiently inhibited the decrease of mitochondrial membrane potential in ethanol-injured LO2 cells. Molecular docking revealed that YP-4 and LP-4 possess potential inhibitory activity on CYP2E1 and thus reduce ethanol-induced oxidative stress. It is suggested that YP-4 and LP-4 have good hepatoprotective effect against alcoholic liver injury.     

Antioxidant activity of predigested protein obtained from a range of farmed edible insects

This study investigated the antioxidant activities of peptides obtained by in vitro gastrointestinal digestion of edible insects. The antioxidant potential of edible insects' hydrolysates was determined as the free radical‐scavenging activity, ion chelating activity and reducing power. The highest antiradical activity against DPPH^˙, whose IC₅₀ value is the lowest, was noted for Amphiacusta annulipes (19.1 μg/mL) and that against ABTS^˙+ was the highest for Zophobas morio (4.6 μg/mL). The peptides obtained from A. annulipes also showed the highest Fe²⁺ chelation ability (58.82%) and reducing power (0.652). The highest ability to chelate Cu²⁺ was noted for Locusta migratoria (86.05%). The locust was characterised by the highest concentration of peptides before digestion and after digestion (3.13 and 5.88 mg/mL, respectively), and the DH was 36.29%.     

Protein hydrolysate from salmon frame debittered by plastein reaction: amino acid composition,characteristics and antioxidant activities

Impacts of plastein reaction on bitterness, physicochemical and antioxidant properties of salmon frame hydrolysate with the aid of various proteases (alcalase and papain) at different concentrations and varying reaction temperatures were investigated. Plastein was produced from hydrolysate by papain at 40°C, which had 30% degree of hydrolysis (30DHP). Rearrangement of peptides in hydrolysate was performed by 1% papain at 40°C for 10 h, yielding plastein namely ‘30DHP-P1’. It showed the lowest bitterness (P < 0.05) than other plasteins and hydrolysates. Surface hydrophobicity was not related well with bitterness. Therefore, the size of peptides also determines the bitterness. 30DHP-P1 had augmented solubility; however, its antioxidant activities (DPPH and ABTS radical scavenging activities and ferric reducing antioxidant power) were slightly lower (P < 0.05) than those of hydrolysates. Bitterness of hydrolysate was markedly debittered via plastein reaction under optimal condition. Plastein generally had lighter colour and still possessed antioxidant activity.     

Thermal recovery of antioxidant activity from carnosol quinone,the main antioxidation product of carnosol

The antioxidant reaction of carnosol, a phenolic diterpene of sage and rosemary, produced ortho‐ and para‐quinone derivatives. Although the orthoquinone derivative of carnosol (CARQ) is stable in a lipophilic solution and has a very weak antioxidant activity, the thermal treatment of CARQ in lipid restored strong antioxidant activity. HPLC analysis of the thermal recovery reaction clarified that the strong activity was mainly due to the reproduced carnosol. A possible mechanism for the production of carnosol from CARQ is the self‐redox reaction of CARQ. Two of the oxidation products from CARQ in the thermal recovery reaction were identified to be rosmariquinone and dehydrorosmariquinone. Copyright © 2004 Society of Chemical Industry     

Effects of ultrasound-assisted enzymatic hydrolysis and monosaccharides on structural,antioxidant and flavour characteristics of Maillard reaction products from sweet potato protein hydrolysates

Effects of ultrasound (US)-assisted enzymatic hydrolysis and different monosaccharides (arabinose; xylose, XY; galactose and glucose) on peptide structure, antioxidant activities and flavour characteristics of Maillard reaction products (MRP) from sweet potato protein hydrolysates were investigated. US markedly enhanced the MR progress, and USXY showed the lowest pH value of 5.04, the highest browning intensity and fluorescence intensity (P < 0.05). FTIR results revealed significant peptide structure changes in USXY, USAR and USGA compared to other samples. USXY exhibited the highest Oxygen radical absorbance capacity (ORAC) value of 109.15 µg TE/mL, followed by USGA and USAR (94.07 and 93.41 µg TE/mL), respectively (P < 0.05). USXY and USAR showed different aroma features as compared to other MRP (P < 0.05). In addition, US enhanced umami, sweetness and sourness attributes and reduced bitterness of all MRP. USXY exhibited the highest umami intensity score (7.4), followed by USGA (7.3) and USAR (7.2), respectively. Partial least square regression analysis showed that the stronger umami taste was strongly correlated to aldehydes, thiophenes, MW 1000–3000 and 500–1000 Da peptides. Thus, US-assisted enzymatic hydrolysis and MR with xylose (XY) could be a promising way to produce natural flavouring with improved antioxidant activity.     

Cellular antioxidant effect of bioactive peptides and molecular mechanisms underlying: beyond chemical properties

Bioactive peptides are known for their chemical antioxidant activities. However, the importance of cellular antioxidant peptides has relatively been overlooked; nevertheless, scientific evidence supporting their potential to prevent chronic diseases associated with oxidative stress is progressively increasing. Cellular in vitro and in vivo studies have demonstrated that antioxidant bioactive peptides possess cellular antioxidant activity, decrease oxidative stress biomarkers (e.g. lipid peroxidation, intracellular ROS levels, apoptosis), increase diverse antioxidant enzymes’ activities and modulate levels of antioxidant molecules. These cellular in vitro bioactive properties and in vivo health effects suggest that antioxidant peptides could be used as components of functional foods and contribute to health promotion by improving specific physiological functions. This review highlights the scientific evidence about cellular antioxidant activity of bioactive peptides, their protective effect and underlying molecular mechanisms of action. It also describes the underlying antioxidant mechanisms and the structure–function relationship of antioxidant peptides.     

大豆肽的制备及其美拉德反应产物特性研究

本文以高温大豆粕为原材料,模拟酱油制曲工艺,通过发酵和酶解技术制备大豆肽,研究大豆肽及其美拉德反应产物的特性。通过比较其蛋白质回收率、DPPH自由基清除率等抗氧化指标、褐变程度及其肽分子量分布情况,深入研究了发酵酶解工艺和酶解时间对大豆肽及其美拉德产物抗氧化特性的影响。研究发现,发酵和酶解处理均可显著提升高温大豆粕的蛋白质回收率和抗氧化活性,在酶解时间为24 h时大豆粕的回收率达到最大值77.21%,此时大豆粕酶解产物的DPPH自由基IC50值和还原力(A700)分别为0.77 mg/m L和0.16。而美拉德反应则可以进一步提升大豆粕酶解产物的抗氧化活性。另外美拉德反应过程中分子质量较大的组分热降解反应比较剧烈,而小分子寡肽则比大分子多肽具有更高的美拉德反应活性。     

Characteristics and antioxidant activity of ultrafiltrated Maillard reaction products from a casein–glucose model system

Maillard reaction products (MRPs) were prepared from casein–glucose by refluxing for 130 min at 102 °C and initial pH 12.0 without pH control to investigate the characteristics of casein–glucose Maillard reaction and the antioxidant activity difference among different fractions of MRPs. Browning and intermediate products increased, however, the pH of the system decreased with increase in the heating time. Free amino group content decreased 78% during first 10 min and did not change nearly thereafter. Amino acid analysis indicated that lysine and arginine decreased significantly, and casein was partially hydrolysed to peptides or free amino acid. High molecular weight compounds were dominant in the MRPs, determined by high performance gel-filtration chromatography. After ultrafiltration, antioxidant activity of each MRPs fraction was investigated by DPPH radical-scavenging activity, reducing power, Fe²⁺ chelating activity and lecithin oxidation assay. MRPs of different molecular weight exhibited distinctly different antioxidant activities.