Antioxidative activity of water extract of sweet potato leaves in Taiwan

This study reports the preparation of four varieties of water extract from sweet potato leaves from Taiwan, including TNG10, TNG57, TNG66 and YSP, and evaluates their antioxidative activity. The EC₅₀ values (scavenging DPPH radicals) of TNG10, TNG57, TNG66 and YSP were 0.27 ± 0.01, 0.19 ± 0.01, 0.41 ± 0.02, and 0.31 ± 0.02 mg/ml, respectively, on a freeze-dry weight basis. The total phenolic contents of these water extracts were in the order: TNG57 > TNG10 > TNG66 > YSP. The TNG10 and TNG57 extracts exhibited better reducing power and scavenging effects of superoxide radicals than did TNG66 and YSP. At a concentration of 1 mg/ml, TNG10 and TNG57 significantly protected HaCaT cells from H₂O₂-induced cytotoxicity. The water extracts of YSP had more flavonoids than had those of TNG66 which may have contributed to their higher activity in many antioxidative assays. These results suggest that the water extracts of all four varieties of sweet potato leaves, and especially TNG10 and TNG57, display potent antioxidative effects.     

酶法水解马铃薯蛋白技术的研究

阐述马铃薯蛋白的提取以及用酶法水解马铃薯蛋白的工艺和方法.确定胰蛋白酶的最佳水解条件是:pH值为8.0、水解时间为2 h、水解温度为55℃、酶用量为650 U/g、固液比为1:5,得到了收率高、水溶性好的马铃薯水解蛋白.     

Antioxidative peptides derived from milk proteins

Antioxidants may function by preventing the formation of radicals or by scavenging radicals or hydrogen peroxide and other peroxides. Milk contains several antioxidant factors, like vitamins and enzymes. Possible antioxidant activity of milk proteins and hydrolysates has also been shown. Peptides generated from the digestion of milk proteins are reported to have antioxidative activities. Milk-derived antioxidative peptides are composed of 5–11 amino acids including hydrophobic amino acids, proline, histidine, tyrosine or tryptophan in the sequence. The structure–activity relationship or the antioxidant mechanism of peptides is not fully understood. Antioxidant activity of the hydrolysates seems to be inherent to the characteristic amino acid sequences of peptides derived, depending on the protease specificity. The results suggest that the hydrolysates from milk proteins could be used as natural antioxidants in enhancing antioxidant properties of functional foods and in preventing oxidation reaction in food processing. Further studies are needed to elucidate the role of antioxidative peptides in the protective function in humans.     

Antioxidative and anti-inflammatory activities of an ethanol extract from fig (Ficus carica) branches

The edible fruit of common fig (Ficus carica) or just the fig has been traditionally used for treating hemorrhoids, insect stings, gout, ulcers, and skin infections such as warts and viruses. An ethanol extract of fig branches and its ethyl acetate, hexane, butanol, and water fractions were prepared and examined for their abilities to scavenge free radicals and inhibit inflammatory reactions. Our data showed that the ethyl acetate fraction contained the largest amount of phenolic compounds and showed the highest free radical scavenging activity. Every fraction of fig, particularly the ethanol extract and the ethyl acetate and hexane fractions, inhibited nitric oxide production in RAW264.7 cells. Tumor necrosis factor-α level also decreased significantly in all groups tested. Our results demonstrate that fig branches possessed pharmacological activity and might be useful for developing antioxidant or antiinflammatory agents.     

碎米蛋白ACE抑制肽制备工艺的研究

研究了以碎米为原料,酶法制备血管紧张素转换酶(ACE)抑制肽的工艺。采用不同的蛋白酶对碎米蛋白进行水解,以水解液对ACE抑制率为评价指标,结果得出风味蛋白酶为最佳水解酶;通过单因素和正交试验,确定最佳的酶解工艺条件:pH为7.0,酶解温度为55℃,料液比为3%,酶解时间3h,风味蛋白酶酶添加量4000U/g。在此条件下ACE抑制肽的抑制率为85.4%。     

甘薯多酚提取液的抑菌试验研究

以最小抑菌浓度、最小杀菌浓度及抑菌率为指标测定甘薯多酚提取液对食品中常见微生物的抑菌活性,并研究温度、pH等对提取液抑菌活性的影响。结果显示:甘薯多酚提取液对大肠杆菌、金黄色葡萄球菌、蜡样芽孢杆菌等几种细菌有较强的抑制作用,尤其对金黄色葡萄球菌的抑菌效果最为明显,而对枯草杆菌、啤酒酵母、产黄青霉、黑曲霉等仅在高浓度时才表现出一定的抑制作用。甘薯多酚提取液有较好的热稳定性,在pH为4～5时,对于大肠杆菌、金黄色葡萄球菌和枯草杆菌的抑菌作用最强。     

Antioxidant activity of peptides isolated from alfalfa leaf protein hydrolysate

Alfalfa leaf protein, a potential source of high quality protein for human consumption, was hydrolyzed with protease. Alfalfa leaf protein hydrolysate was fractionated by ultrafiltration and the obtained peptides were purified by dynamical adsorption. The antioxidant activity of alfalfa leaf peptides (ALPs) was investigated and compared with that of a native antioxidant, reduced glutathione (GSH), which was used as a reference. The reducing power of ALPs was 0.69 at 2.00 mg/mL. ALPs at 1.60 mg/mL and 0.90 mg/mL exhibited 79.71% and 67.00% of scavenging activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide radical, respectively. In addition, ALPs showed 65.15% chelating effect on ferrous ion at 0.50 mg/mL. The molecular weight of the peptides was determined and 67.86% of the total amount was below 1000 Da. Combined with the result of the amino acid profiles, ALPs was believed to have high nutritive value in addition to antioxidant activity.     

几种中药浸提物的抗氧化活性研究

研究了山楂、白蒺藜及枸杞乙醇和水浸提物在卵黄脂蛋白不饱和脂肪酸(PUFA)过氧体系中的抗氧化活性,并比较了几种浸提物对OH·自由基和O·-自由基的清除能力,结果表明:3种中药在PUFA体系具有不同的抗氧化能力;山楂和白蒺藜具有一定的清除OH·的能力;3种中药均具有较强的清除O·-的能力。     

Antioxidative activities of some commercially honeys,royal jelly,and propolis

The antioxidative effects of some honeys, royal jelly, and propolis were evaluated using a lipid peroxidation model. Activities gradually decreased over time. Buckwheat honey, pure honey (Chinese milk vetch), and propolis were the most active among honeys. Excepting royal jelly and propolis, the activities of all honeys were drastically decreased by heat treatment. The superoxide-scavenging activities of each honey, royal jelly, and propolis decreased in the order: propolis>royal jelly>buckwheat honey>honey (Japanese bee)>mixed-breed honey>pure honey (acacia)>commercially available honey>pure honey (Chinese milk vetch).     

Ultrasound-assisted generation of ACE-inhibitory peptides from casein hydrolyzed with nanoencapsulated protease

BACKGROUND: Bioactive peptides generated from milk proteins are eminent ingredients for functional foods and nutraceuticals. Amongst several approaches to release these peptides, hydrolysis of milk proteins with proteolytic enzymes is a promising choice. It is, however, required to inactivate the enzyme after a predetermined time, which leads to impurity of the final product. Immobilization of enzyme molecules can overcome this problem as it simplifies enzyme separation from the reaction mixture. A fungal protease from Aspergillus oryzea was encapsulated within nanoparticles yielded via silicification of polyamidoamine dendrimer template generation 0. It was used to hydrolyze the dominant milk protein (casein) in the absence or presence of sonication. The production of angiotensin converting enzyme (ACE)‐inhibitory peptides was monitored during hydrolysis. RESULTS: Sonication did not affect maximum ACE‐inhibitory activity but shortened the process sixfold. Ultrafiltration permeate of the centrifugal supernatant of casein solution hydrolyzed during sonication inhibited ACE activity as efficiently as the supernatant obtained from it. CONCLUSION: The protease from Aspergillus oryzea encapsulated within nanospheres is suitable for generation of ACE‐inhibitory peptides from casein. The nanoncapsulation procedure is simple, rapid and efficient. This may enable the industrial production of functional products from milk. Copyright © 2011 Society of Chemical Industry     

Antioxidative and antibacterial peptides derived from bovine milk proteins

The search for alternative preservatives is on the rise due to safety issues linked with the application of synthetic antioxidants and the extensive increase in bacterial resistance to several conventional antibiotics. Therefore, the quest for finding suitable alternatives including bioactive peptides has received attention. This article reports a comprehensive insight concerning antioxidative and antibacterial peptides derived from milk proteins, a prolific source of peptides having various bioactivities. Caseins and whey proteins have also been evaluated for antioxidative and antibacterial potential using the BIOPEP database. A notable number of potentially active peptides are present in milk proteins. Technological approaches are here reported for the production of these peptides. The findings of this review show potentiality of utilizing dairy derived antioxidative and antibacterial peptides in the development of a superior alternative to the current generation of preservatives and therapeutic agents, as well as a functional ingredient in dietetic or pharmaceutical applications.     

新疆自然发酵驼乳中酵母菌的分离鉴定及部分酶学特性研究

为了了解自然发酵驼乳中酵母菌的组成及其在发酵过程中的作用,对采自新疆的酸驼乳样品中的酵母菌及其部分酶学特性进行了研究.共有3株酵母菌从2份发酵驼乳样品中分离,通过表型特征和大亚基D1/D2序列分析,将IMAU30001和IMAU30003鉴定为Kluyveromyces marxianus,IMAU30002鉴定为Saccharomyces cerevisiae.3株菌都不产生蛋白酶和脂肪酶.IMAU30001和IMAU30003产生β-半乳糖苷酶的量分别为0.8645±0.1431μg/mL·min·mg和0.6637 ±0.2204μg/mL·min·mg.     

钩藤提取物抗氧化作用的研究

对钩藤以正己烷、乙酸乙酯、甲醇在索氏提取器中依次提取4 h,并对乙酸乙酯提取物和甲醇提取物进行了色谱分离,测定了各成分的抗氧化活性,通过显色反应和光谱分析对各成分进行了初步鉴定.结果表明,钩藤中有两种黄酮苷元和一种黄酮苷的抗氧化活性比BHT强,两种黄酮苷与BHT相近,3种酚酸和几种羟基蒽醌甙也有较强的抗氧化能力,但钩藤碱的抗氧化能力较差.     

牡蛎肉酶解液的抗氧化工艺研究

采用胰蛋白酶酶解牡蛎肉蛋白,以酶解液清除DPPH自由基的效果为分析指标,采用单因素和正交试验,分析酶解的固液比、加酶量、时间、温度对酶解效果的影响,研究酶解的最佳工艺参数。结果显示,牡蛎肉酶解的最优水平组合为固液比1:3、加酶量0.25%、酶解时间2h、酶解温度45℃,牡蛎肉酶解液抗氧化性最强。     

乳清蛋白肽美拉德反应产物的制备及其抗氧化特性的评价

以乳杆菌A-2发酵乳清蛋白与乳糖发生美拉德反应,制备得乳清蛋白肽美拉德反应产物,对其进行分离纯化并研究抗氧化活性。将乳杆菌A-2接种于复原乳清粉培养基经热加工得发酵产物,经Sephadex G 15层析柱分离,采用SDS-PAGE图谱证实乳杆菌A-2发酵乳清粉在干热处理条件下确实发生了美拉德反应;以抗坏血酸(维生素C)和丁基羟基茴香醚(BHA)为阳性对照,用ABTS法和ORAC法来测定和评价乳杆菌9029乳清蛋白发酵产物的抗氧化作用。在反应体系中,H-DPWF-1、BHA和维生素C的ABTS清除率分别是77.38%、86.47%和73.95%,H-DPWF-1清除ABTS自由基的能力的介于维生素C和BHA之间;样品H-DPWF-1的相对ORAC值为3.43mmol TE/g,维生素C的相对ORAC值为9.67mol TE/g,即H-DPWF-1清除AAPH的能力为维生素C的1/3。结果显示H-DPWF-1具有较强的抗氧化活性,具有广阔应用前景和潜力。     

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.     

以鱼类下脚料制备风味蛋白粉的研究

以鱼类下脚料为原料,经生物酶解、酸解制备了风味水解蛋白粉。文中介绍了制作方法和生产工艺,以及产品的相关技术特征。     

苹果幼果中酚类物质抗氧化活性研究

为研究苹果幼果多酚抗氧化活性强弱,实验采用四种体外抗氧化评价体系:亚铁还原能力（ferric reducing ability of plasma,FRAP）,DPPH法,邻苯三酚自氧化体系及邻二氮菲-Fe3+-H2O2法初步研究其抗氧化活性。结果表明,苹果幼果多酚具有较强的总还原能力,幼果多酚浓度为90μg/m L时,其对DPPH·、O-2·及·OH的最大清除率分别可达96.96%、70.61%和82.20%,且不同浓度幼果多酚与相应浓度阳性对照间差异显著（p<0.05）。相关性分析表明,幼果多酚与Fe SO4当量浓度、DPPH·清除率、O-2·清除率及·OH清除率之间均存在明显的量效关系。苹果幼果多酚是一种优良的天然抗氧化剂和自由基清除剂。      

胃蛋白酶酶解大豆蛋白苦味肽的粗分离

为了从根本上解决大豆蛋白酶解苦味的问题,从分离大豆酶解苦味肽入手,测其肽氨基酸组成、排列顺序,研究了酶—基质的切割点以及切割点与苦味肽的关系,从而有目的选择酶—基质控制水解反应以避免或减少苦味肽的产生。在上样量1.5mL,流速0.5mL/min,每管接收洗脱液2.5mL,缓冲液浓度为0.05mol/L磷酸盐—0.15mol/NaCl的洗脱条件下,ShephadexG-15交联葡聚糖凝胶柱(1.5cm×76cm)的标准洗脱曲线方程为-lgKav=0.00567M2-0.18279。用其对胃蛋白酶水解大豆蛋白的苦味肽进行粗分,得到3个苦味肽粗品,其苦味值为5,3,2.5,分子量为868,651和361u。