Antarctic krill antioxidant peptides show inferior IgE-binding ability and RBL-2H3 cell degranulation

Enzymatic hydrolysis,isolation,and purification might make a great deal of difference in antioxidant activity and antigenicity of peptide components.This study aimed to isolate and purify antioxidant peptide components from Antarctic krill and evaluate their allergenicity of them.Electron paramagnetic resonance(EPR)spectroscopy results indicated 3-10 kDa Antarctic krill hydrolysates(AKHs)had higher DPPH and·OH radical scavenging rates.And the second component(N2-2)purified 3-10 kDa hydrolysate showed better ability to scavenge DPPH and·OH radicals(P<0.05),which were(47.43±2.18)%and(34.33±1.25)%,respectively.Additionally,indirect-ELISA results revealed that N2-1 had a weaker ability to bind specific IgE and that N2-2 had a lower binding capability to specific IgG1(P<0.05).And N2-2 had a higher EC50 value of(5.29±0.95)ng/mL(P<0.05)in cell degranulation assay,which was about 13.80 times that of Antarctic krill.Therefore,N2-2 might be the potential source of the antioxidant peptides with lower allergenicity.

Antioxidant peptides encrypted in flaxseed proteome:An in silico assessment

Flaxseed proteins and antioxidant peptides(AP)encrypted in their sequences were analysed in silico with a range of bioinformatics tools to study their physicochemical properties,allergenicity,and toxicity.Nine proteases(digestive,plant and microbial sources)were assessed for their ability to release known APs from 23 mature flaxseed storage proteins using the BIOPEP database.The families of proteins identified were predominantly globulins,oleosins,and small amount of conlinin.Overall,253 APs were identified from these proteins.More peptides were released by enzymatic hydrolysis from the globulins than those from oleosins and conlinin.Compared with other enzymes studied,the plant proteases(papain,ficin,and bromelain)were found to be superior to releasing APs from the flaxseed proteins.Analysis of toxicity by ToxinPred showed that none of the peptides released was toxic.Most of the APs showed structural features that are important for antioxidation,including relatively low molecular weight(dipeptides and tripeptides only);amphipathic properties(hydrophobicity range of-0.5 to+0.5);relatively low Boman index(≤2);broad range of pI(3.7-10.8),and an abundance of antioxidant amino acid residues(e.g.glutamic acid and histidine).This study demonstrate the suitability of flaxseed proteins as a source of APs.

Production and Purification of Antioxidant Peptides from Flatfish Skin Protein Hydrolysates

Antioxidant peptides of flatfish skin protein hydrolyzed by four enzymes （Papain, Pepsin, Trypsin and Neutrase, respectively）were investigated. The Trypsin hydrotysate obtained by hydrolysis exhibited the highest 1,1- dipheny-l-2-picrylhydrazyl（DPPH） radical scavenging activity （DRSA） compared with other hydrolysates. Re- sponse surface method ology （RSM）, based on Box-Behnken design, was used to study the influence of hydrolysis conditions on the DRSA. The optimal hydrolysis conditions were as follows： pH 7.38, temperature 48.2~C and en- zyme/substrate （E/S）ratio 2 840 U/g. Under these conditions, the maximum DRSA was （22.85 ＋ 0.57）%. The experimental values agreed with the value （23.09%） predicted by the model within a 95% confidence interval. By using gel filtration chromatography and reversed-phase high performance liquid chromatography （RP-HPLC）, anti- oxidant peptide （D2-P）was isolated from flatfish skin protein hydrolysates （FSPH）and could exhibit a （54.28 ± 1.37） % scavenging activity on DPPH radical at the concentration of 5 mg/mL. This is the first report of a scientific basis for the preparation of antioxidant peptides from flatfish skin. The results suggested that the antioxidant pep- tides can be exploited into functional foods or used as a novel source of nutraceuticals.

Novel Antioxidant Peptides Derived from Enzymatic Hydrolysates of Macadamia Protein

In the present work, macadamia protein was enzymatic hydrolyzed to produce peptides which had abundant antioxidant activities. The relative antioxidant capacity was investigated through some in vitro models such as scavenging activity of DPPH radical, scavenging of ABTS+ radical and evaluation of the total antioxidant capacity assay. Macadamia protein was characterized by methods of DEAE cellulose cation-exchange chromatography and SDS-PAGE. Besides, method of price graph was used to compare the difference and to investigate the connection between the actual and ideal antioxidant value of the hydrolysates, aiming to reduce this difference.

Peptidomic analysis of whey protein hydrolysates and prediction of their antioxidant peptides

Enzymatic hydrolysis of proteins is a breakdown process of peptide bond in proteins,releasing some peptides with potential biological functions.Previous studies on enzymatic hydrolysis of whey proteins have not identified the complete peptide profiles after hydrolysis.In this study,we reconstructed a profile of peptides from whey hydrolysates with two enzymes and different processing conditions.We also developed an ensemble machine learning predictor to classify peptides obtained from whey hydrolysis.A total of 2572 peptides were identified over three process conditions with two enzymes in duplicate.499 peptides were classified and chosen as potential antioxidant peptides from whey proteins.The peptides classified as antioxidants in the hydrolysates had a proportion of 13.1%-24.5%regarding all peptides identified.These results facilitate the selection of promising peptides involved in the antioxidant properties during the enzymatic hydrolysis of whey proteins,aiding the discovery of novel antioxidant peptides.

Tartary buckwheat(Fagopyrum tataricum(L.)Gaertn)protein-derived antioxidant peptides:mechanisms of action and structure-activity relationship in Caco-2 cell models

Excessive reactive oxygen species(ROS)can cause oxidative damage and lead to various metabolic disease.Tartary buckwheat(Fagopyrum tataricum(L.)Gaertn)is a new kind of protein-rich functional food,the protein in which has been proved to have good antioxidant capacity.In this study,in order to further explore the antioxidant mechanism of Tartary buckwheat protein,4 peptides(CR-8,LR-8,GK-10 and SR-12)were isolated and identified from it.H2 O2 was used to induce oxidative damage to Caco-2 cells to evaluate antioxidant capacity of these peptides.The results of superoxide dismutase(SOD),total antioxidant capacity(T-AOC)and mitochondrial membrane potential etc.showed that these peptides have superior antioxidant capacity.CR-8 has the best antioxidant capacity.In order to further clarify the antioxidant mechanism of CR-8,metabolomics was used to analyze related metabolites and metabolic pathways.The results showed that after CR-8 intervention,the content of metabolites such as L-acetyl carnitine has increased.This indicated that CR-8 can improve the antioxidant capacity of damaged cells by intervening in multiple metabolic pathways.This also revealed the anti-oxidant mechanism of tartary buckwheat protein.In conclusion,it provided a theoretical basis for further studying the activity of tartary buckwheat portein and utilizing buckwheat resources.

Purification and Identification of Antioxidant Peptides from the Scallop Skirts of Mimachlamys Nobilis

The processes of scallop meats can produce a large amount of by-products like scallop skirts,which are rich in nutrients. This work aimed to obtain the information about antioxidant peptides derived from scallop skirts of Mimachlamys nobilis. The hydro-lysates obtained by trypsin exhibited the highest antioxidant activity( 75.6%,79.5% and 76.7% using DPPH,hydroxyl and superoxide anion radical scavenging activity assays,respectively). The antioxidant peptides( MNAP) were separated and purified using UF membranes,GFC processes and RP-HPLC,and the antioxidant activity of MNAP was identified to be 85.7% using DPPH radical scavenging activity assay. The peptides( MNAP) were composed of two peptides with their molecular weights2 855.6 Da and 3 007.2 Da using MALDI-TOF-MS,respectively. The results suggested that the scallop skirts of Mimachlamys nobilis could be explored as a source of antioxidant peptides.

In vitro Antioxidant Effects of Porphyra haitanensis Peptides on H_2O_2-Induced Damage in HepG2 Cells

In this study,protein from Porphyra haitanensis was used as raw material to prepare an antioxidant peptide,and its antioxidant activity was evaluated in vitro.A model of H_2O_2-induced oxidative damage in Hep G2 cells was established,and the effects of Porphyra haitanensis hydrolysates (PHHs) on superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were detected.Finally,the structure of PHHs was identified by ESI-MS/MS.The results showed that the 1,1-diphenyl-2-pyridylhydrazine(DPPH)-free radical-scavenging ability of PHHs was the strongest (59.28%at 1.0 mg m L~(-1)) when hydrolyzed with an acidic protease for 4 h.PHHs with different concentrations had protective effects on H_2O_2-induced damage to Hep G2 cells,and the protective effect was enhanced with increasing concentrations.When the level was 400μg m L~(-1),the cell survival rate was as high as 88.62%.Moreover,PHHs can significantly reduce oxidative damage to Hep G2 cells by H_2O_2,improve SOD activity,and reduce MDA content.The tetrapeptide Asp-Lys-Ser-Thr,with a molecular weight of 448 Da,was identified as an important fraction of PHHs by high-resolution mass spectrometry.

Comparative Study on the Antioxidant Activity of Peptides from Pearl Oyster(Pinctada martensii) Mantle Type V Collagen and Tilapia(Oreochromis niloticus) Scale Type Ⅰ Collagen

In this study, Pearl oyster mantle type V collagen(POMC) and tilapia scale type I collagen(TSC) were extracted and hydrolyzed by various proteases in order to obtain peptides. The antioxidant activity of the peptides was investigated by DPPH, hydroxyl radical scavenging experiments and a dynamic digestion model in vitro. The results show that there are significant differences in amino acid composition between POMC and TSC. The collagen peptides obtained from pearl oyster mantle(POMCP) by treating with alkaline protease exhibited higher antioxidant activity than that from tilapia scale(TSCP) treated with papaya protease, and both of them showed greater DPPH and hydroxyl radical scavenging activity than other peptides. After being separated via Sephadex G-25 chromatography, the M1 fraction isolated from POMCP, and the S1 fraction from TSCP with which both had higher molecular weights showed the strongest antioxidant activity than other fractions, and the M1 fraction exhibited stronger antioxidant activity than the S1 fraction in scavenging free-radicals and protecting cells from the oxidation damage. Furthermore, after treating the dynamic digestion system model in vitro, the DPPH and hydroxyl radical scavenging activity of the M1 fraction increased slightly. These results suggest that POMCP exhibits stronger antioxidant activity than TSCP, which means that PMOP may be a good candidate to be a potential natural antioxidant in the food-processing industry.

Antifatigue,Antioxidant and Immunoregulatory Effects of Peptides Hydrolyzed from Manchurian Walnut(Juglans mandshurica Maxim.) on Mice

The Manchurian walnut(Juglans mandshurica Maxim.) is rich in proteins, whereas this resource has not been used efficiently. The antifatigue, antioxidative and immunoregulatory effects of Manchurian walnut hydrolysate peptides(MWHPs)were evaluated in this study. MWHPs with a degree of hydrolysis of 32.23% were ultrafiltered and divided into three fractions,namely, high(> 10 k Da), medium(3–10 kDa), and low molecular weight(< 3 kDa), and then fed to mice continuously at doses of 200, 400 or 800 mg/(kg·d). The antifatigue, antioxidative, and immunoregulatory effects of the peptides were tested on the second and fourth weeks of MWHP administration. Results showed that low-molecular-weight MWHPs exerted significant antifatigue(prolonging swimming time, elevating liver glycogen contents, and reducing lactic acid contents), antioxidative(enhancing superoxide dismutase(SOD), GSH-Px, and catalase(CAT) activities and reducing malondialdehyde(MDA) content), and immunoregulatory(raising the immune-organ index and promoting T-lymphocyte proliferation and s Ig A secretion in the intestinal tract) effects. This research indicates that MWHPs have potential applications in health care and may be developed as a base for new functional foods.

Production,purification and activity evaluation of three novel antioxidant peptides obtained from grass carp(Ctenopharyngodon idella)scale waste by microbial protease BaApr1 hydrolysis

In this study,an alkaline protease BaApr1 from the Bacillus altitudinis W3 was chosen to hydrolysis grass carp(Ctenopharyngodon idella)scales.The hydrolysate of alkaline protease BaApr1 exhibited the best antioxidant activity compared to other protease hydrolysates.The optimal hydrolysis conditions for BaApr1 were an enzyme dosage of 1250 U/g,a hydrolysis time of 7 h,a pH of 9.5 and a temperature of 50℃.Three novel peptides were purified using ultrafiltration,anion exchange chromatography,gel filtration chromatography and ultra-performance liquid chromatography,and their sequences were identified as Tyr-Val-Gln-Ala-Gly-Ala-Ala-Gly-Ala-Ala-Ala-His(SHP2),Val-Lys-Leu-Tyr-Val-Leu-Leu-Val-Pro(SHP4),and Val-Gln-Val-Leu-Ala-Gly-Pro-Val-Val-Lys-Leu-Tyr(SHP5)with molecular weights of 1086.53 Da,1043.69 Da and 1285.79 Da,respectively.Among them,SHP2 exhibited the highest scavenging activity on DPPH;(EC_(50)4.08 mg/mL),ABTS+;(EC_(50)0.23 mg/mL)and HO;(EC_(50)2.78 mg/mL),and the strongest reducing power.Additionally,SHP5 can significantly inhibit lipid peroxidation in the linoleic acid system.In conclusion,three peptides isolated from scales of hydrolysate of grass carp showed great antioxidant activity and might be used as potential food ingredients and pharmaceuticals.

Changes of the Content and Antioxidant Activity of Natural Peptides in Germinated Soybeans

[ Objective] This study aimed to investigate the content and antioxidant activity of natural peptides in various soybean sprouts during the germination process. [Method] By using black soybean sprouts, yellow soybean sprouts and green soybean sprouts as raw materials, the content, DPPH ·clearance rate, OH · clearance rate and reduction capacity of natural peptides in various soybean sprouts at different germination time were determined, to evaluate the antioxidant capacity of natural peptides and compare it with that of Vc. [ Result] The results showed that the contents of natural peptides in black soybean sprouts, yellow soybean sprouts and green soybean sprouts varied at different germination time. To be specific, the content of natural peptides in black soybean sprouts reached the maximmn of 0. 194 mg/g at 2 d post-germination; the content of natural pepfides in yellow soybean sprouts reached the maximum of 0.231 mg/g at 2 d post-germination; the content of natural peptides in green soybean sprouts exhibited a negative correlation with the germination time, which reached the maximum of 0. 164 mg/g at 1 d post-germination. [ Conclusion] According to the determination of DPPH ·clearance rate, OH ·clearance rate and reduction capacity of natural peptides in three varieties of soybean sprouts, natural peptides in yellow soybean sprouts possess the highest antioxidant activity, followed by those in black soybean

Study on the Molecular Weight Composition and Antioxidant Activity of Peanut Bioactive Peptides

[ Objective] To prepare peanut bioactive peptides and analyze their molecular weight composition and antioxidant activity. [ Method ] The dialysis bag of 8.0, 3.5 and 1.0 kD were used to classify the hydrolyzate derived from alcalase and flavourzyme, peanut bioactive poptides of differ-ent molecular weight were obtained and then their scavenging capacity of free radicals was measured. The molecular weight composition was stud-ied by Tricine-SDS-PAGE.[Result] The content of peptides 〈 1.0 kD were 76.21% and 83.42% in the total hydrolyzate from alcalase and fla-vourzyme respectively. All hydrolyzate with different molecular grades showed free radical scavenging capacity, which was increased with the reduc- tion of molecular mass. The peptides 〈 1.0 kD exhibited higher radical scavenging capacity of （87.41 ±0.66） % （alcalase） and （67.88 ±0.48）% （ flavourzyme）, respectively. [ Conclusion] Peanut bioactive peptides had strong effect of antioxidant capacity, especially that 〈 1.0 kD, which had great prospect.

Antioxidant Activity of Peptides Obtained from Cotton Ground Oil-Cake Proteins

Antioxidant activity of the peptides derived from proteins of defatted cottonseed kernels and cotton ground oil-cake by their enzymatic hydrolysis with acidic （Asp. niger） and neutral proteinases （Bac. amyloliquefaciens） was studied. Antioxidant activity of the derived peptides depended on the used proteins and enzymes. The peptides derived by using of neutral proteinase possessed higher antioxidant activity, in comparison with the peptides derived by acidic proteinases.

Review on marine collagen peptides induce cancer cell apoptosis,necrosis,and autophagy by reducing oxidized free radicals

Marine collagen peptides(MCPs)are natural products prepared by hydrolyzing marine collagen protein through a variety of chemical methods or enzymes.MCPs have a range of structures and biological activities and are widely present in marine species.MCPs also have a small molecular weight,are easily modified,and absorbed by the body.These properties have attracted great interest from researchers studying antioxidant,anti-tumor,and anti-aging activities.MCPs of specific molecular weights have significant anti-tumor activity and no toxic side effects.Thus,MCPs have the potential use as anti-cancer adjuvant drugs.Free radicals produced by oxidation are closely related to human aging,cancer,arteriosclerosis,and other diseases,but their relationship with cancer is not well known.In this review,we focus on the antioxidant properties of MCPs in the treatment of cancer,highlighting their antioxidant molecular structure and potential for clinical practice.

橄榄仁抗氧化肽的分离鉴定及分子对接

该研究利用酶解法结合凝胶色谱柱从橄榄仁中分离纯化得到6个抗氧化肽,采用分子对接模拟6种抗氧化肽与超氧化物歧化酶(superoxide dismutase, SOD)的结合机制。采用酶解法从橄榄仁中提取抗氧化活性肽,以水解度、DPPH自由基清除率为指标,从6种商用酶中筛选出最适蛋白酶为木瓜蛋白酶,以底物浓度、酶底比、酶解时间、温度进行单因素试验,选取影响酶解反应的3个因素(酶底比>温度>时间)进行响应面法优化得出最佳工艺条件为底物质量浓度50 g/L、酶底比为3.3%(质量分数)、温度20℃、时间88 min。对最优条件下的粗肽液进行SephadexG-25和SephadexG-15分离纯化得到6个具有良好活性的抗氧化肽,分别为WLSF、TSVLR、LVYLVR、AGGKPFQ、YYPFKGFA、AFNVDERLAR。TSVLR显示出最高的DPPH自由基清除活性81.07%和羟自由基清除能力42.48%。分子对接研究表明,纯化的肽通过疏水效应和氢键与抗氧化相关的关键蛋白SOD有效结合。结果表明,橄榄仁可作为天然食物来源制取功能性食品的一个新的探究方向。

英国红芸豆抗氧化肽对氧化应激斑马鱼的保护作用研究

为探究英国红芸豆抗氧化肽组分(BRKBPAPC)的体内抗氧化作用,利用2,2′-偶氮二异丁基脒二盐酸盐诱导建立氧化应激斑马鱼模型,研究BRKBPAPC对氧化应激斑马鱼的影响。结果表明:BRKBPAPC能显著提高(P<0.05)斑马鱼体内过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)的活力和总抗氧化能力(T-AOC),显著降低(P<0.05)丙二醛(MDA)含量;同时BRKBPAPC还具有调节斑马鱼脂代谢的能力,随着处理浓度的增加斑马鱼脂代谢指标逐渐恢复正常水平;高剂量BRKBPAPC可使斑马鱼行为轨迹增多,高速运动次数、时间、距离显著上升。高剂量抗氧化肽处理21 d时,CAT、SOD、T-AOC、GSH-Px分别增至(28.29±3.29)、(126.59±6.39)、(2.07±0.18)、(84.75±7.77)U/mg prot,MDA含量降至(3.35±0.29)nmol/mg prot。由此可见,BRKBPAPC具有较好的体内抗氧化作用及脂代谢调节能力。

马乳源性生物活性肽生物学信息及其抗肺癌作用靶点探索

在前期研究基础上通过在线软件对已知氨基酸组成的马乳源性活性肽生物学信息和关键靶蛋白进行分析并进行分子对接,探索马乳源性活性肽抗肺癌作用靶点。结果表明马乳源的活性肽为不稳定、带正电荷的亲水性多肽,是没有跨膜区和信号肽,也没有糖基化和磷酸化位点的细胞膜外多肽,二级结构主要以无规则卷曲为主,与肺癌相关的核心靶点即CTNNB1、FGFR2、FOXF1、KRAS、NKX2-1、TGFBR2具有很好的结合亲和力,为深入研究马乳源活性肽的生物学功能奠定了基础。

玉米肽螯合钙纳米粒的制备及结构表征分析

为了探明玉米肽与钙离子螯合纳米粒的结构与特性,以小分子玉米肽(CPT)为钙离子螯合载体,采用有机溶剂沉淀法制备玉米肽纳米螯合钙(CPT-Ca)复合纳米粒,研究了其制备工艺、结构表征及体外抗氧化活性。结果表明,玉米肽螯合钙(CPT-Ca)的最佳制备条件为:玉米肽与氯化钙质量比40∶1,pH 7.0,螯合时间为60 min,温度为50℃,此条件下肽钙螯合率为(81.20±3.55)%。该螯合钙粒子的平均粒径为(396.0±8.0)nm,多分散系数为0.043,Zeta电位为(-22.6±0.7)mV,具有良好的纳米粒子微观结构特性;傅里叶红外光谱(FTIR)、紫外吸收光谱(UV)和X射线衍射图谱(XRD)显示,玉米肽上的氨基与羧基提供结合位点以配位键方式与钙离子结合,形成新的肽-钙螯合物;抗氧化实验表明,螯合钙具有较好的羟基和DPPH自由基清除自由基能力。玉米肽螯合钙纳米粒对于改善钙离子的结构分布和体内外传递吸收,开发新型玉米肽功能食品与钙离子补充剂具有重要作用。

AB-8大孔树脂-C18柱联用分离干腌牛肉抗氧化肽的研究

该文利用盐酸提取法提取了干腌牛肉多肽,借助AB-8型大孔树脂及C18球形硅胶柱的分离纯化出4种抗氧化肽,利用分子对接模拟了4种抗氧化肽与超氧化物歧化酶(superoxide dismutase,SOD)的结合位点。利用盐酸提取法提取了抗氧化肽并测试其在1、2、3、4、5 mg/mL的抗氧化能力,发现在5 mg/mL时,DPPH自由基、ABTS阳离子自由基和超氧阴离子自由基(·O_(2)^(-))清除率分别为86.24%、35.62%和54.34%。对比了AB-8、D101、S-8、X-S、HPD-500、NKA-9的吸附率与解吸率,AB-8的吸附率与解吸率最好,分别为92.55%和82.88%。研究优化了AB-8的上样流速、上样量、乙醇洗脱浓度和洗脱流速,在4 BV/h上样流速、39 mL上样量、75%(体积分数)乙醇溶液洗脱剂和1 mL/min洗脱流速时,可以分离出3个组分(A、B和C),测试3个组分的抗氧化能力,B组分的DPPH自由基、ABTS阳离子自由基和·O_(2)^(-)清除能力最高,分别为73.33%、21.01%和63.33%。对B组分进行C18柱分离,分离出4个抗氧化肽:FDGDF、TGPGPW、FLSDH和KPFDAK。与SOD(PDB ID;1E9O)进行分子对接,发现FDGDF、TGPGPW、FLSDH和KPFDAK均可以与SOD形成氢键,结合能分别为-6.7、-6.55、-6.6、-7.35 kcal/mol,1 mg/mL的FDGDF可以有效增加SOD活力11.64%,酶活力单位增加697 U/mL,研究结果为干腌牛肉制品的开发提供理论基础。