Antioxidative properties of aqueous and aroma extracts of squid miso prepared with Aspergillus oryzae-inoculated koji

To evaluate the antioxidative properties of a newly developed fermented paste (squid miso) prepared from squid mantle flesh with Aspergillus oryzae-inoculated koji, we used in vitro models, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, nitric oxide (NO) and carbon-centered radical-scavenging activity (RSA), reducing power ability (RPA), and linoleic acid oxidation. The antioxidant activity of volatile compounds, which were extracted from squid miso by dichloromethane, was confirmed based on the results obtained by the oxidation models consisting of carotene linoleate and hexanal. The RSA of the miso against several radicals, including DPPH, hydroxyl, nitric oxide and carbon-centered radicals measured by ESR spectrometry increased gradually through the fermentation period. On the other hand, the RPA increased rapidly in early stages of fermentation. Proteins were hydrolyzed to peptides and amino acids during fermentation. Certain peptides of low molecular mass significantly contributed to RSA. 4-Ethylguaiacol in the RSA active fraction, which was obtained by column chromatography, was the most potent antioxidative in the volatile extract. Analysis of phenolics in ethyl acetate fraction clearly suggested that 4-ethylguaiacol in the squid miso is possibly a bioconversion product of ferulic acid derived from koji. However, the aqueous extracts containing antioxidative peptides contributed more remarkably to radical scavenging than heterocyclic volatiles and phenolics.     

Beyond antioxidant actions: Insights into the antioxidant activities of tyr-containing dipeptides in aqueous solution systems and liposomal systems

Tyr-containing dipeptides deserve close attention because of their interesting bioactivities. This study aimed to make a contribution to the antioxidant activity evaluation of these dipeptides, through examining the chemical reactions underlying the results obtained in ABTS, ORAC assays and liposomal systems. Among Tyr-Tyr, Tyr-Phe, Phe-Tyr, Tyr-Ala and Tyr-Ser, Tyr-Tyr displayed the highest activity in all methods. Compared with Tyr-Phe, Phe-Tyr exhibited a higher activity in ORAC assay but a lower activity in ABTS assay. In liposomal systems, significant differences were found among the dipeptides in antioxidant actions against lipid peroxidation initiated by water or lipid-soluble radicals. Electron and/or hydrogen transfer were involved in the detected antioxidant actions, with the location of Tyr at the C-/N-terminus being a crucial factor. Besides the structural features of peptides, the characteristics of liposomes, location of lipid oxidation initiation and peptide distribution in/on liposomal membranes all influenced the outcome of antioxidant actions.     

Purification and characterisation of antioxidative peptides from enzymatic hydrolysates of venison protein

To prepare antioxidative peptides from venison protein hydrolysates (APVPH), six proteases were employed for enzymatic hydrolysis, and the antioxidative activities of the hydrolysates were investigated using a free radical scavenging assay. Among the hydrolysates, papain hydrolysates which had the highest free radical scavenging activity were further separated into four groups and purified using consecutive chromatographic methods. Finally, two antioxidative peptides were obtained, and their sequences identified as Met-Gln-Ile-Phe-Val-Lys-Thr-Leu-Thr-Gly (APVPH I) and Asp-Leu-Ser-Asp-Gly-Glu-Gln-Gly-Val-Leu (APVPH II). The free radical scavenging activity of APVPH I was higher than that of APVPH II, and the IC₅₀ values of the hydroxyl, DPPH, superoxide, and peroxyl radical scavenging activities were 44, 77, 217, and 85 μg/ml, respectively. These results indicate that enzymatic hydrolysates of venison protein possess potent antioxidative activity.     

Antioxidative activities of caffeoyl-proline dipeptides

The benefits of antioxidants in treating degenerative diseases, delaying ageing and preserving food, have been extensively studied. In our previous study, we found that caffeoyl-Pro-His dipeptide (CA-Pro-His-NH₂) showed the highest antioxidative activity among the histidine- containing caffeic acid dipeptides (CA-His-Xaa-NH₂ and CA-Xaa-His-NH₂). We assumed that the addition of proline to the CA-Pro-His-NH₂ structure may synergistically enhance its antioxidative activity. Therefore, we synthesised twenty different caffeoyl-proline dipeptides (CA-Pro-Xaa-NH₂), and evaluated their antioxidative activities with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation inhibition tests. Some of the CA-Pro-Xaa-NH₂ showed higher free radical scavenging activities than CA, and even CA- CA-Pro-His-NH₂. However, CA-Pro-His-NH₂ still exhibited the highest antioxidative activity in reducing lipid peroxidation.     

蜂王浆水溶性蛋白及其酶解产物的抗氧化活性

本研究分别采用清除二苯基-2- 苦肼自由基(DPPH·),抑制亚油酸氧化和总抗氧化能力测定等方法,探讨蜂王浆水溶性蛋白及其酶解产物的抗氧化特性。结果表明,蜂王浆水溶性蛋白(WSPs)本身的抗氧化活性很弱,但酶解后抗氧化活性增强,其中胃蛋白酶和胰蛋白酶共同酶解产物(PT-WSPs)的抗氧化活性最强。对WSPs 及其酶解产物进行膜分离后发现,分子量小于3kD,尤其是小于1kD 的肽类物质其清除DPPH·、抑制亚油酸氧化及总抗氧化能力最强。     

含酪氨酸二肽在脂质体体系中的抗氧化活性与供电子能力

采用紫外波段扫描对5 种含酪氨酸二肽（酪氨酸-酪氨酸、酪氨酸-苯丙氨酸、苯丙氨酸-酪氨酸、酪氨酸-丙氨酸和酪氨酸-丝氨酸）的紫外吸收特性进行检测，并采用还原力法、循环伏安法及2,2-偶氮二(2-甲基丙基咪)二盐酸盐诱导氧化脂质体模型对其抗氧化活性进行评价及比较，以探究影响5 种含酪氨酸二肽抗氧化活性的因素及其在均相与非均相体系中的活性差异与联系。结果表明：构成含酪氨酸二肽的氨基酸组成及排列顺序对于二肽的紫外吸收特征、供电子能力以及脂质氧化抑制率有显著影响，其中酚羟基的数量对其抗氧化活性起决定性作用。与酪氨酸-苯丙氨酸相比，苯丙氨酸-酪氨酸在3 种抗氧化活性评价方法中均显示出更高的活性。在脂质体体系中，含酪氨酸二肽的脂质氧化抑制率除了与其供电子能力显著相关（P＜0.05）外，还与其自身的亲脂或亲水性具有一定的相关性。     

Isolation and identification of antioxidative peptides from hydrolysate of threadfin bream surimi processing byproduct

The objective of this study was to determine the antioxidant activity and possible mode of action of partially purified peptides derived from threadfin bream surimi byproduct. The frame, bone and skin (FBS) byproduct, which was obtained from a deboning process, was hydrolyzed by Virgibacillus sp. SK33 proteinase and fractionated using anion exchange and size exclusion chromatography. Three fractions, i.e., B1, B2 and B3, were obtained, and the amino acid sequences of the peptides in all 3 fractions were determined using LC-MS/MS. Fractions B2 and B3 contained higher amounts of Trp, Met, Cys and Tyr residues than fraction B1. Fraction B3 exhibited high ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP), while metal chelation and hydroxyl radical scavenging ability were principle modes of action of peptides in fraction B2 and B3. In addition, fraction B1 and a synthetic peptide selected from the pooled de novo peptides of fraction B3, FLGSFLYEYSR, had a cellular radical scavenging effect when HepG2 cells were treated with H₂O₂.     

甘薯叶柄藤类黄酮的体外抗氧化作用研究

研究薯蔓黄酮(FSPV)的体外抗氧化作用。测定了FSPV对二苯代苦味酰自由基(DPPH)、超氧阴离子自由基(O2·)和羟自由基(·OH)的清除率,同时用硫代巴比妥酸(TBA)法测定其对亚油酸的抗氧化性。实验结果表明:FSPV对DPPH的清除效果良好(IC50=8.60mg/L);对O2·清除能力强于芦丁但弱于VC;对·OH的清除能力强于芦丁和VC;对亚油酸也有很好的抗氧化作用。体外实验证实,FSPV具有较强的抗氧化能力。     

发酵法制备鱼鳔多肽及其抗氧化活性研究

将米曲霉接种于鱼鳔匀浆液中对其进行直接发酵,利用菌产蛋白酶的作用水解鱼鳔蛋白。随着发酵时间的延长,发酵液水解度不断上升,发酵液中的多肽含量不断增加。对发酵所得鱼鳔多肽进行超滤,采用产O2·和·OH 化学模型研究其清除自由基的活性,采用亚油酸自氧化体系研究其抗氧化活性。结果显示,经发酵40h,水解度(22 ± 0.8)% 所得鱼鳔多肽体外抗氧化能力较强;超滤片段中,平均肽链长度为12 个氨基酸残基的多肽超滤液体外抗氧化能力较强;分子量分布在1000D 左右。发酵法所得鱼鳔多肽不仅对自由基具有强烈的清除作用,还能明显抑制脂质的氧化。     

羟脯氨酸小肽的体外抗氧化活性

羟脯氨酸作为胶原蛋白的特征成分,其在肽序列中可使胶原衍生低聚肽对肽酶或蛋白酶产生高度抗性,口服后经过胃肠消化吸收至血液中仍能以肽的形式存在。羟脯氨酸小肽可在肠上皮细胞膜部位被完整吸收,并在血浆达到较高的水平,具有良好的吸收率和生物利用度以及更稳定、高效的生物活性。本实验以15 条羟脯氨酸小肽为研究对象,采用1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)（2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonicacid),ABTS）阳离子自由基、超氧阴离子自由基和羟自由基4 种体外方法对其抗氧化活性进行评价。结果表明：在15 条羟脯氨酸小肽中,Leu-Hyp的DPPH自由基清除率最高,为23.6%;Leu-Hyp、Ile-Hyp的ABTS阳离子自由基清除率最高,分别为57.8%和57.7%;其他小肽的DPPH自由基和ABTS阳离子自由基清除能力均较低,清除率均小于15%或不具有ABTS阳离子自由基清除能力。浓度为3 mmol/L时,15 条小肽的羟自由基和超氧阴离子自由基清除能力均较强,清除率分别可达30%～50%和60%～80%。综上,本实验所选15 条羟脯氨酸小肽均具有一定的羟自由基和超氧阴离子自由基清除能力,其中Leu-Hyp、Ile-Hyp的体外抗氧化性最好。     

牛乳酪蛋白抗氧化乳基料的制备及其分离纯化

为制备具有低过敏性和抗氧化作用的牛乳酪蛋白活性肽乳基料,以水解度和·OH清除率为指标,先后采用大孔吸附树脂和凝胶过滤色谱分离、纯化酪蛋白酶解物。结果表明：胰蛋白酶和中性蛋白酶组合酶解牛乳蛋白6h,其产物具有较高的水解度(36.80%)和较好的抗氧化活性,·OH清除率的半抑制浓度(IC50)值为3.12mg/mL;酶解物通过LS106大孔吸附树脂分离、纯化后,体积分数为75%的乙醇洗脱液具有较高的抗氧化活性,其·OH清除率的IC50值为0.14mg/mL;体积分数75%的乙醇洗脱组分经凝胶过滤色谱分离、纯化后,得到4个不同相对分子质量肽段,其中抗氧化活性较强肽段的相对分子质量为355.38～854.89,其·OH清除率的IC50值为0.09219mg/mL,与酶解物相比其抗氧化活性扩大33.84倍;相对分子质量小于3238.05的多肽占纯化后多肽总量的60.32%,30.09%多肽是由2～8个氨基酸组成的寡肽。牛乳酪蛋白经复合酶酶解后其抗氧化活性明显提高,过敏性明显降低,喷雾干燥后可以直接制备乳基料。     

黑蚂蚁蛋白的酶解优化及抗氧化肽的超滤膜分离

本文研究了酶量、温度、pH和时间四个因素对黑蚂蚁蛋白的碱性酶法水解的影响。通过响应面设计,以各个抗氧化活性为指标,优化了超氧自由基清除率,DPPH自由基清除率,羟基自由基清除率,还原力和亚油酸自氧化抑制作用最强的酶解工艺条件。验证实验证实方程的准确率达95%以上。采用超滤膜及离子交换色谱对酶解产物进行了分离,发现5-10 kDa和1-3 kDa组分的抗氧化能力最强,碱性肽对超氧自由基清除能力、羟基自由基清除能力、亚油酸自氧化抑制作用贡献较大,酸性肽对DPPH自由基清除能力及还原力的贡献较大。     

不同水解度蜂王浆蛋白体外抗氧化活性的分析

探讨不同水解度的蜂王浆蛋白水解物在体外的抗氧化活性,为新蜂王浆制品的研制提供理论依据。测定了不同酶解度的蜂王浆蛋白酶解物在体外对DPPH自由基清除能力、羟自由基清除能力、还原力和抗脂质过氧化能力。得出蜂王浆蛋白对DPPH自由基清除能力、羟自由基清除能力、还原力和抗脂质过氧化能力的最佳水解度分别为4.18%、4.50%、4.18%、4.50%。该结论对今后研制具有不同抗氧化功能的蜂王浆制品,具有一定的理论指导价值。     

槲皮素-锌(Ⅱ)配合物清除自由基的活性研究

为改善槲皮素的水溶性,将其制成锌(Ⅱ)配合物,测定了槲皮素-锌(Ⅱ)配合物对四种自由基——DPPH·、·OH自由基、O-2·自由基以及烷基自由基的清除能力,并同VC、BHT进行了比较。并通过体内实验,测定其在小鼠体内的总抗氧化能力。结果表明:在实验质量浓度范围内(0.05～1.2mg/mL),槲皮素-锌(Ⅱ)配合物对DPPH·、·OH自由基、O-2·自由基的清除率可达90.51%、85.65%和79.81%;其对烷基自由基的抑制率为82.67%,且其抗氧化活性强于VC和BHT。小鼠体内的总抗氧化能力的测定结果显示,槲皮素-锌(Ⅱ)配合物在高剂量时具有最大抗氧化力,为12.7980±0.9131单位/mL血清。结果表明,槲皮素-锌(Ⅱ)配合物是一种有效的自由基清除剂。     

Isolation of antioxidative and ACE inhibitory peptides from protein hydrolysate of skipjack (Katsuwana pelamis) roe

Bioactive peptides from protein hydrolysate of defatted skipjack (Katsuwonus pelamis) roe with 5% degree of hydrolysis (DH) prepared by Alcalase digestion were isolated and characterised. Two active fractions with ABTS radical scavenging activity (973.01–1497.53 μmol TE/mg sample) and chelating activity (0.05–0.07 μmol EE/mg sample) from consecutive purification steps including ultrafiltration, cation exchange column chromatography and reverse phase high performance liquid chromatography (RP-HPLC), were subjected to analysis of amino acid sequence by LC–MS/MS. Seven dominant peptides with 6–11 amino acid residues were identified as DWMKGQ, MLVFAV, MCYPAST, FVSACSVAG, LADGVAAPA, YVNDAATLLPR and DLDLRKDLYAN. These peptides were synthesised and analysed for ACE-inhibitory activity and antioxidative activities. MLVFAV exhibited the highest ACE inhibitory activity (IC₅₀ = 3.07 μM) (p < 0.05) with no antioxidative property, whilst DLDLRKDLYAN showed the highest metal chelating activity, ABTS radical and singlet oxygen scavenging activities. Therefore, peptides prepared from skipjack roe could be further employed as a functional food ingredient.     

Characterization of honey from different floral sources. Its functional properties and effects of honey species on storage of meat

The antioxidative effects of honey species and their related products were evaluated using a lipid peroxidation model system. The antioxidant activities of honey species gradually decreased with passage of time. Buckwheat honey was as effective as 1 mM α-tocopherol. Superoxide-scavenging activities of propolis and royal jelly were strongest among the honey species tested. 1,1-Diphenyl-2-picrylhydrazyl radical scavenging ability of sample species were lower than those of 1 mM ascorbic acid and α-tocopherol. Hydroxyl radical scavenging activity was very high in all honeys (over 77% inhibition). From the results of the bacterial test on storage of meat and muscle, each honey exhibited the inhibition of bacterial growth. In particular, propolis and royal jelly exhibited the strongest inhibitory effects against bacterial growth. This suggests that honey species from different floral sources possess strong antioxidative and antibacterial activities and are scavengers of active oxygen species.     

鳕鱼多肽的抗氧化活性及其分离纯化

研究了鳕鱼多肽的抗氧化活性及分离纯化.为获得高纯度的抗氧化肽,将鳕鱼多肽依次通过超滤、凝胶过滤层析、阴离子交换层析(Q-FF)和反相高效液相色谱层析(RP-HPLC)进行分离纯化.结果表明:鳕鱼多肽具有很强的清除羟自由基的能力、清除DPPH的能力和还原能力;经Q-FF柱层析分离得到了B1、B2和B3 3个组分,B2经RP-HPLC检测显示为单一峰,获得了纯度较高的鳕鱼多肽,这为鳕鱼多肽的开发利用提供了科学理论依据.     

黑花生衣色素抗氧化作用的研究

为研究黑花生衣色素的抗氧化能力,对黑花生衣色素溶液进行紫外-可见光谱扫描,并分别测定黑花生衣色素的还原能力,清除羟自由基、超氧阴离子自由基、DPPH自由基的能力以及抗脂质过氧化功能。结果表明:黑花生衣色素的紫外光谱图显示在223nm和278nm处有两个最大吸收峰,与可可色素和高粱红色素等天然抗氧化物质的紫外吸收图谱相似;对羟自由基、超氧阴离子自由基、DPPH自由基的半抑制能力IC50分别为0.601、0.496、0.208mg/mL,对脂质过氧化有很强的抑制作用,是一种效果较好的天然抗氧化剂。     

大豆生物活性肽的分离及其抗氧化活性研究

为制各具有抗氧化活性的大豆生物活性肽,本实验采用酶解处理大豆蛋白粉,对酶解产物进行葡聚糖Sephadex G-25凝胶柱层析分离,并对其各组分分子量分布及其抗氧化性进行了研究,对抗氧化活性最佳的肽段进行氨基酸组成分析。结果显示,大豆蛋白酶解物经Sephadex G-25分离后得到了六个肽片段,其中平均链长为4,即含有2～6个氨基酸残基的大豆功能短肽SPP4,对羟自由基具有最佳的清除作用,清除率达到80．13%,氨基酸组成分析发现该组分中缬氨酸、亮氨酸、苯丙氨酸、赖氨酸含量较高。结果表明,含2～6个氨基酸残基的大豆生理活性短肽具有较好的抗氧化活性。     

Purification and characterisation of an antioxidative peptide from enzymatic hydrolysates of duck processing by-products

Duck processing by-products were hydrolysed using eight proteases to produce an antioxidative peptide. Of the various hydrolysates produced, the pepsin extract exhibited the highest hydroxyl radical scavenging activity. The derived peptide was purified using high-performance liquid chromatography (HPLC) to identify any potent radical scavenging activity. The sequence of the antioxidative peptide obtained was identified as Asp-Val-Cys-Gly-Arg-Asp-Val-Asn-Gly-Tyr, with a molecular weight of 1096 Da. The IC₅₀ value of purified peptide for hydroxyl radical scavenging activity was 75 μg/ml as the measurement by an electron spin resonance (ESR) spectrometer. In addition, the purified peptide exhibited a protective effect on H₂O₂-induced DNA damage. These results indicate that the purified peptide possesses a potent antioxidative activity and protective effect of DNA against H₂O₂-induced oxidative damage.