Identification of bioactive peptides in commercial Cheddar cheese

This study examined the presence of antimicrobial, antioxidant and antihypertensive peptides in three commercially available Australian Cheddar cheeses. Peptide extracts as well as fractionated peptide extracts were examined. Commercial cheese A peptides exhibited the greatest inhibition against Bacillus cereus and also commercial cheese A fractionated peptides greater than 10 kDa showed the highest inhibition against B. cereus. Commercial cheese A peptides also showed the highest inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH), a free radical used to measure antioxidant activity. All cheese fractionated peptides greater than 10 kDa demonstrated higher inhibition of DPPH after fractionation. Antihypertensive peptides were determined by inhibition of the angiotensin-converting enzyme (ACE). Overall, commercial cheese A had the lowest concentration required to inhibit ACE and commercial cheese A fractionated peptides lower than 5 kDa had the lowest inhibition after fractionation. These preliminary findings suggest that peptide extracts of three commercial Australian Cheddar cheeses exhibit antimicrobial, antihypertensive and antioxidant properties.     

响应面法优化草菇抗氧化肽的酶法制备工艺

以草菇为原料提取蛋白质,蛋白酶酶解蛋白制备抗氧化肽。以DPPH自由基清除率为指标,在单因素实验基础上,结合响应面法优化草菇抗氧化肽的提取工艺。通过超滤分离纯化获得不同分子量的肽段,采用DPPH自由基清除率、Fe2+螯合率和还原力法测定超滤组分的抗氧化活性。结果表明:中性蛋白酶为最优酶解蛋白酶,最佳酶解工艺条件为酶解时间3.70 h,加酶量3.81%,底物质量浓度3.11 g/100 mL,在此条件下,酶解产物的DPPH自由基清除率为69.85%±2.52%。通过超滤分级制备所得分子量最小的肽段F1（<3 kDa）具有最高的抗氧化活性,其DPPH自由基清除率、Fe2+螯合率和还原力分别为78.81%±1.56%、91.05%±1.65%、0.47±0.02。草菇抗氧化肽可作为潜在的天然抗氧化剂来源得到开发利用。     

Antioxidant activities of red pepper (Capsicum annuum) pericarp and seed extracts

In this study, we examined the antioxidant activities of red pepper (Capsicum annuum, L.) pericarp and red pepper seed extracts. The extracts were evaluated by various antioxidant assays, including 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, superoxide anion radical scavenging, hydroxyl radical scavenging, [2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid)] (ABTS) radical scavenging, ferrous chelating activity, superoxide dismutase (SOD) activity and reducing power, along with the determination of total phenolic and flavonoid contents. All the extracts showed strong antioxidant activity by the testing methods. The red pepper pericarp extract exhibited strong ferrous chelating activity and high scavenging activity against free radicals, including both the hydroxyl and DPPH radicals, but it exhibited weaker scavenging activity for the superoxide anion radical and for SOD. In contrast, the red pepper seed extract exhibited strong SOD activity and high scavenging activity against the superoxide anion radical, but showed weaker ferrous chelating activity, hydroxyl radical scavenging, and DPPH radical scavenging. We observed that the reducing power level and ABTS radical scavenging activity of the red pepper seed were higher than those of the red pepper pericarp at the highest tested concentration. Most of the test results for the red pepper seed and red pepper pericarp extracts increased markedly with increasing concentration; however, the metal chelating, SOD and ABTS radical scavenging activities did not increase with the concentration. Highest total phenolic and flavonoid contents were obtained from the red pepper pericarp extracts. Overall, the red pepper seed and red pepper pericarp extracts were highly effective for the antioxidant properties assayed, with the exceptions of ferrous chelating activity, hydroxyl radical scavenging and SOD activity.     

金华火腿粗肽液的体外抗氧化活性

在金华火腿长期加工过程中,蛋白质在内源酶作用下产生了大量不同长短的肽段.提取金华火腿粗肽液,通过测定不同质量浓度粗肽液清除自由基、螯合金属离子、抑制脂质过氧化和蛋白质氧化的能力,并与相应质量浓度的丁基羟基甲苯(BHT)和谷胱甘肽(GSH)作比较,衡量金华火腿粗肽液的抗氧化能力.结果表明:随着质量浓度的增加,金华火腿粗肽液的抗氧化能力显著增加.在质量浓度为1.5mg/mL时,金华火腿粗肽液清除羟基自由基能力达到90％;质量浓度为5mg/mL时,金华火腿粗肽液清除1,1-二苯基-2-三硝基苯肼(DPPH)自由基能力与BHT和GSH相当,高达95％;金华火腿粗肽液螯合金属离子的能力显著高于BHT和GSH;当质量浓度为4mg/mL时,金华火腿粗肽液具有和BHT和GSH相当的抑制脂质过氧化能力,并能一定程度抑制蛋白质氧化.结论:金华火腿粗肽液的抗氧化能力与BHT与GSH相当.     

In vitro evaluation of the antioxidant activities in fruit extracts from citron and blood orange

Consumers are increasingly aware of diet related health problems and therefore demanding natural ingredients which are expected to be safe and health-promoting. Recently, number of studies on health benefits associated with citrus phytochemicals have been demonstrated. In the present study, an attempt has been made to isolate antioxidant fractions from two different citrus species such as Citron (Citrus medica) and blood orange (C. sinensis). Antioxidant fractions were extracted from mature, ripe fruits using five different solvents using a Soxhlet extractor. The total phenolic content of the extracts was determined by Folin–Ciocalteu method. MeOH:water (80:20) extract of citron and acetone extract of blood orange was found to contain maximum phenolics. The dried fractions were screened for their antioxidant activity potential using in vitro model systems such as 1, 1-diphenyl-2-picryl hydrazyl (DPPH), phosphomolybdenum method and as well as by the nitroblue tetrazolium (NBT) reduction test at different concentrations. The MeOH:water (80:20) fraction of citron showed highest radical scavenging activity 42.5%, 77.8% and 92.1% at 250, 500 and 1000 ppm, respectively, while MeOH:water (80:20) fraction of blood orange showed lowest DPPH radical scavenging activity at all the tested concentrations. Furthermore, all the fractions showed remarkable antioxidant capacity by the formation of phosphomolybdenum complex. In addition, superoxide radical scavenging activity was assayed using non-enzymatic (NADH/phenaxine methosulfate) superoxide generating system. All the extracts showed variable radical scavenging activity. The data obtained in the in vitro models clearly establish the antioxidant potency of citrus fruit extracts. However, comprehensive studies need to be conducted to ascertain the in vivo safety of such extracts in experimental animal models. To the best of our knowledge, this is the first report on antioxidant activity of citron and blood orange varieties of citrus fruits.     

Antioxidant activity of stem and root extracts of Rhubarb (Rheum ribes): An edible medicinal plant

The antioxidant activity of chloroform and methanol extract of roots and stems of Rhubarb (Rheum ribes L.), which are used for medicinal purposes and also its fresh stems and petioles are consumed as vegetable, was studied. The antioxidant potential of both extracts of roots and stems were evaluated using different antioxidant tests, namely total antioxidant (lipid peroxidation inhibition activity), DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging, superoxide anion radical scavenging, ferric reducing power, and cupric reducing power (CUPRAC), and metal chelating activities. Total antioxidant activity was also measured according to the β-carotene bleaching method, and all four extracts exhibited stronger activity than known standards, namely butylated hydroxytoluene (BHT) and α-tocopherol. Particularly, higher activity was exhibited by roots with 93.1% and 84.1% inhibitions of chloroform and methanol extracts, while 82.2% and 82.0% inhibitions by stem extracts, respectively. However, both methanol extracts exhibited higher DPPH radical scavenging activity than the corresponding chloroform extracts, moreover, methanol extract of the stems showed better activity than BHT. In addition, both root extracts showed more potent superoxide anion radical scavenging activity than BHT, and comparable with well known radical scavenger l-ascorbic acid. Except chloroform extract of the roots, the other three extracts exhibited better metal chelating activity than quercetin. Also, total phenolic and flavonoid contents in both extracts of the roots and stems of R. ribes were determined as pyrocatechol and quercetin equivalents, respectively.     

A new flavone from antioxidant extracts of Pistacia terebinthus

Acetone and methanol extracts of the fruits of Pistacia terebinthus L. subsp. terebinthus L. were studied for their antioxidant activity by investigating their total phenolic and flavonoid contents, β-carotene bleaching potential, DPPH radical scavenging effect, scavenging activity on superoxide anion radical, reducing power, and metal chelating effect on ferrous ion. Both extracts showed very similar chemical profile by checking on TLC plates, and exhibited high scavenging activity on superoxide anion radical and DPPH radical. Due to these similarities they were combined and fractionated on a silica gel column for their constituents, and the most active three fractions in DPPH assay were purified to afford a new flavone 6′-hydroxyhypolaetin 3′-methyl ether (1) besides a group of known flavonoids apigenin, luteolin, luteolin 7-O-glucoside, quercetin, quercetagetin 3-methyl ether 7-O-glucoside, isoscutellarein 8-O-glucoside. Their structures were established by UV, UV shift reagents, and ¹H NMR spectroscopic techniques. Antioxidant activity of the new flavone was investigated by β-carotene bleaching and DPPH radical scavenging activity methods, and it showed a high activity in the first system, but not so good in the latter.     

Comparative study on the antioxidant activity of methanolic and aqueous extracts from the fruiting bodies of an edible mushroom <Emphasis Type="Italic">Pleurotus djamor</Emphasis>

In vitro antioxidant activities, total phenolic, and flavonoid contents of Pleurotus djamor extracts were analyzed based on radical scavenging activities of methanol and aqueous extracts using 1,1-diphenyl-2-picryl-hydrazyl (DPPH), N,N-dimethyl-p-phenylenediamine (DMPD), total Fe³⁺ reducing power, CUPRAC, phosphomolybdenum, metal chelating activity, and lipid peroxidation inhibition assays. Both extract types showed efficient radical scavenging activities against DPPH and DMPD radicals, ferric (Fe³⁺) and cupric (Cu²⁺) ion reducing powers, metal chelating activities, and lipid peroxidation inhibition. Total phenolic contents of methanol and aqueous extracts were 2.79 and 5.95 mg of GAE/g, respectively. Flavonoid contents of methanol and aqueous extracts were 6.35 and 5.75 mg of CAE/g, respectively. Consumption of the mushroom P. djamor can be beneficial due to antioxidant properties.     

丝瓜花不同溶剂提取物抗氧化活性及其酚类成分分析

以无水乙醇、70%乙醇、40%乙醇和水分别对丝瓜花进行提取,并测定各提取物中总酚、总黄酮含量,采用DPPH·清除能力、超氧化物自由基清除能力、FRAP抗氧化能力和亚铁离子螯合能力等方法评价其抗氧化活性,通过HPLC分析其中酚类成分。结果表明,70%和40%乙醇提取物总酚及总黄酮含量较高,而且DPPH·清除活性、FRAP还原力最强,40%乙醇提取物、水提物分别具有最强的超氧阴离子自由基清除活性和亚铁离子螯合能力。总酚含量与DPPH·清除活性之间存在较强的相关性(R²=0.8688)。HPLC分析检出提取物中9种酚类化合物,其中含量最高的为杨梅素。试验结果说明,70%乙醇、40%乙醇可能是丝瓜花抗氧化性物质提取的较好溶剂。结果表明丝瓜花是一种较好的抗氧剂资源。     

模拟胃肠液环境下Mozzarella干酪提取液抗氧化活性

为评价干酪成熟过程中形成的活性肽及存活的发酵剂菌种对人体的抗氧化作用,对不同菌种组合Mozzarella干酪的蒸馏水、pH4.6醋酸缓冲液和12%三氯乙酸（TCA）提取液在模拟胃肠液环境下对DPPH自由基的清除率以及还原力进行测定。结果表明,所有不同菌种组合Mozzarella干酪的不同溶剂提取液在模拟胃肠液的环境下具有一定的抗氧化活性,并且模拟肠液的抗氧化活性大大低于模拟胃液环境,活性下降最高达88.35%。添加干酪乳杆菌（Lactobacillus casei）LPC-37的3号Mozzarella干酪提取液在模拟胃肠液环境下的抗氧化活性高于其他Mozzarella干酪,其水、pH4.6醋酸缓冲液、12%TCA提取液在模拟肠液环境下对DPPH清除率分别为73.96%、30.28%、70.27%,还原力分别为0.37、0.18、0.18。     

Bioactives of fruiting bodies and submerged culture mycelia of Agaricus brasiliensis (A. blazei) and their antioxidant properties

Agaricus brasiliensis is a mushroom native from Brazil largely studied due to its polysaccharide contents, particularly β-glucans. In this study, the phenolics and organic acids contents as well as the antioxidant activities of its fruiting bodies and its mycelia obtained from submerged cultivation were compared. The hydroalcoholic extracts obtained from the fruiting bodies, early stationary mycelia and late stationary mycelia contain at least ten phenolic compounds and ten organic acids. Three phenolic compounds were identified as gallic acid, syringic acid and pyrogallol. Eight organic acids were identified as benzoic, oxalic, malic, acetic, alpha-ketoglutaric, citric, fumaric and trans-aconitic acids. All extracts presented antioxidant properties. The latter were evaluated by four assays: DPPH and ABTS radical scavenging activities, chelating ability for ferrous ions and inhibition of lipid peroxidation. The fruiting body extracts were more effective in the DPPH radical scavenging activity and lipid peroxidation inhibition that the mycelia extracts (P ≤ 0.05). The mycelia extracts were more effective in the ABTS radical scavenging activity and ferrous ion chelating ability (P ≤ 0.05). In conclusion, our results show that the mycelia of A. brasiliensis obtained in submerged cultivation can also be, as its fruiting bodies, valuable sources of antioxidant compounds.     

Evaluation of antioxidant activities and total phenolic contents of typical malting barley varieties

Fourteen typical malting barley varieties from China were evaluated for their DPPH radical, ABTS radical cation and superoxide anion radical scavenging activities, reducing power, metal chelating activities, and total phenolic contents (TPC). All barley samples exhibited significant antioxidant activities determined by different assays, and contained significant levels of phenolic compounds. Gan4 and Wupi1 barley exhibited the highest DPPH radical scavenging activity, ABTS radical cation scavenging activity and reducing power. Gan4 and Humai16 barley showed the highest TPC, whereas the highest superoxide anion radical scavenging activity and metal chelating activity were found in Huaimai19 and Ken3 barley, respectively. The Pearson correlation analysis revealed that the TPC showed strong correlations with DPPH radical scavenging activity, ABTS radical cation scavenging activity, and reducing power (P < 0.01), whereas its correlations with superoxide anion radical scavenging activity and metal chelating activity were poor (P > 0.05). Moreover, DPPH radical scavenging activity, ABTS radical cation scavenging activity and reducing power were well positively correlated with each other (P < 0.01). Principal component analysis (PCA) was applied to understand the interrelationships among the measured antioxidant activity evaluation indices, and to gain an overview of the similarities and differences among the 14 barley varieties.     

优选南极磷虾蛋白肽抗氧化活性组分

目的制备南极磷虾抗氧化肽,优选出抗氧化活性最好的南极磷虾肽成分。方法采用脱脂、酶解、超滤等手段制备南极磷虾抗氧化肽;以DPPH自由基清除率、ABTS自由基清除率、抗氧化能力指数3个抗氧化指标和超氧化物歧化酶(superoxide dismutase, SOD)、过氧化氢酶(catalase, CAT)活力2个酶活力指标为评价指标,优选出抗氧化活性最好的南极磷虾肽组分;基于G-25凝胶层析技术对抗氧化活性最好的南极磷虾肽组分进行分离纯化,进一步基于电子顺磁共振(electron paramagnetic resonance,EPR)方法测定洗脱后各峰的DPPH自由基清除率,得到抗氧化活性最好的南极磷虾抗氧化肽组分。结果通过抗氧化指标测定,截留分子量3～10 KDa的肽的DPPH自由基清除率最高,为(30.10±1.10)%,截留分子量3 KDa的南极磷虾肽的ABTS清除能力和抗氧化指数较好,则IC50值为(0.74±0.08) mg/mL、氧化自由基吸收能力(oxygen radical absorbance capacity, ORAC)值为6.39±0.21;通过酶活力指标测定,截留分子量3 KDa的肽的SOD活力和CAT活力最好,分别为(45.7±0.13)U/mg和(17.1±0.19)U/mg蛋白质。对截留分子量3KDa和3～10KDa的南极磷虾肽进行G-25分离纯化后,测定各组分的DPPH自由基清除率,可知截留分子量3～10KDa的F2-2峰清除率最好,为(51.55±1.54)%。结论基于EPR方法优选出分子量为3～10 KDa的南极磷虾肽的F2-2组分的DPPH自由基清除率最高。     

Use of proteases to improve oxidative stability of fermented sausages by increasing low molecular weight compounds with antioxidant activity

Forty fermented sausages from Iberian pigs were manufactured using 3 different proteases with a potential antioxidant activity (batch 1: without proteases, batch 2: neutral bacterial protease, batch 3: fungal protease and batch 4: fungal protease concentrate). The antioxidant properties of extracts (< 3 kDa) from Iberian dry-cured sausages were assessed using four different methods: (i) 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (RSA), (ii) metal chelating assay (MQA), (iii) reducing power (RP) and (iv) inhibition of linoleic acid autoxidation (ILAA). Dry-cured sausage extracts from of all the manufactured batches showed antioxidant activity as indicated by RSA, MQA and ILAA. Manufacturing sausages with the used proteases increased the antioxidant activity of the sausage extracts, except for the MQA. Moreover, extracts from dry-cured sausages which were manufactured without proteases showed the highest levels of both thiobarbituric acid-reactive substances (TBARs) and hexanal content.     

Total phenolic content and antioxidant capacity of extracts obtained from six important fruit residues

The extracts from kinnow peel, kinnow seeds, litchi pericarp, litchi seeds, grape seeds, and banana peel were screened for total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC), 1,1 diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, as well as reducing power. Kinnow peel extract exhibited the highest reducing power, TEAC, and DPPH free radical scavenging activity, whereas, the phenolic content of 37.4 mg GAE/g-dw was highest for grape seed extract. Banana peel extract with a low TPC showed the lowest reducing power, TEAC as well as DPPH free radical scavenging activity among the fruit residue extracts examined in the present study. Correlation analysis between the reducing power and DPPH radical scavenging ability; reducing power and ABTS radical scavenging activity; and ABTS and DPPH radical scavenging abilities showed a high degree of correlation (r² = 0.85-0.91). However, r² of 0.36, 0.66, and 0.49 between TPC and DPPH radical scavenging activity; TPC and reducing power; and TPC and ABTS radical scavenging ability, respectively, indicated that some non-phenolic compounds also contributed to the total antioxidant activity in fruit residue extracts examined in this study. To the best of our knowledge, this is the first paper presenting comprehensive data on TPC, reducing power, and antioxidant activity for the six fruit residues. This study demonstrated that kinnow peel, litchi pericarp, litchi seeds, and grape seeds, can serve as potential sources of antioxidants for use in food and pharmaceutical industry.     

大口黑鲈鱼皮胶原蛋白肽的制备及抗氧化活性研究

目的：探究酶种类对胶原蛋白肽抗氧化活性的影响。方法：从大口黑鲈(Micropterus salmoides)鱼皮中提取胶原蛋白,采用碱性蛋白酶、中性蛋白酶、木瓜蛋白酶和胰蛋白酶酶解胶原蛋白,得到碱性蛋白酶酶解胶原蛋白肽(APP)、中性蛋白酶酶解胶原蛋白肽(NPP)、木瓜蛋白酶酶解胶原蛋白肽(PP)、胰蛋白酶酶解胶原蛋白肽(TP),比较其总抗氧化活性、还原活性、对DPPH·、·OH 和O-2·清除能力以及亚铁离子螯合能力和脂质氧化抑制活性。结果：4种蛋白酶酶解胶原蛋白肽都具有抗氧化活性,且抗氧化能力与胶原蛋白肽浓度呈正相关,其中APP的抗氧化活性最佳,总抗氧化活性和还原活性分别为1.725和0.958,对DPPH·和O-2·清除率分别为56.35%和38.41%。结论：碱性蛋白酶酶解的胶原蛋白肽抗氧化活性更佳。     

Enzyme-enhanced extraction of antioxidant ingredients from red algae Palmaria palmata

The effect of various protease and carbohydrase treatments on the extraction of polyphenols and other antioxidant ingredients from the red algae Palmaria palmata (dulse) was investigated. In addition, the relative contribution of different fractions to the overall antioxidant capacity of the hydrolysate was evaluated. Considerable differences were observed both in total phenolic content (TPC) and antioxidant activities of the hydrolysates evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorbance capacity (ORAC) and ferrous ion-chelating ability assays. All the proteases tested had significant enhancing effect on the extraction of polyphenols and other active components compared to carbohydrases and cold water extraction (control). The Umamizyme extract had the highest TPC and consequently exhibited the strongest scavenging capacity against DPPH and peroxyl radicals. Further fractionation of the Umamizyme extract revealed that the crude polyphenol fraction possessed the highest peroxyl radical scavenging activity, whereas the crude polysaccharide fraction was more effective for chelating ferrous ions. The data from this study suggest the potential of protease treatment to improve value-added utilization of dulse extracts as antioxidants in functional foods and nutraceuticals.     

橄榄酚类提取物的抗氧化性能

为进一步开发利用橄榄中的酚类物质,文中通过测定橄榄酚类提取物的铁离子还原能力、亚铁离子螯合能力,及对2,2'-氨基-二(3-乙基-苯并噻唑啉-6-磺酸)自由基(ABTS+.)、1,1-二苯-2-苦基苯肼自由基(DPPH.)、羟基自由基(.OH)和超氧阴离子自由基(O2-.)的清除能力,以考察橄榄酚类提取物的体外抗氧化性能,并与食品抗氧化剂丁基羟基茴香醚(BHA)和Vc进行对比。结果表明:橄榄酚类提取物具有较好的体外抗氧化性能,其ABTS+.、DPPH.清除率分别高达99%和95%以上,.OH、O2-.清除率可达50%左右,铁离子还原力约1 700μmol/L Trolox,亚铁离子螯合率最高为14.9%。且提取物ABTS+.、DPPH.和.OH清除能力及铁离子还原能力均强于BHA和Vc,而O2-.清除能力强于BHA但弱于Vc。另外,橄榄酚类粗提物和纯化物相同浓度下的ABTS+.、DPPH.、.OH清除能力和铁离子还原能力相当(P>0.05),而其O2-.清除能力和亚铁离子螯合能力表现有所差异。     

不同品种荞麦提取物抗氧化作用的研究

本文以苦荞和甜荞籽粒的乙醇提取物为研究对象,在测定其提取物中总酚酸含量的基础上,利用体外法研究了荞麦提取物的还原力,对Fe2+的络合能力,对DPPH自由基的抑制作用以及对羟基自由基的清除作用。结果表明,5个品种的荞麦乙醇提取物均有显著的抗氧化性,呈剂量效应关系,酚酸含量、还原能力、抗氧化能力之间呈正相关。     

Evaluation of reducing power and radical scavenging activities of water and ethanol extracts from sumac (Rhus coriaria L.)

The purpose of this study was to determine the reducing power, metal chelating, and radical scavenging capabilities of water and ethanol extracts of sumac (Rhus coriaria L.), comparatively. The water and ethanol extracts of sumac were evaluated for their radical scavenging activities by means of the DPPH and DMPD assays. Water extract of sumac (R. coriaria L.) scavenged radicals effectively with EC₅₀ values of 36.4 ??g/ml for DPPH free radical and 44.7 ??g/ml for DMPD cation radical. Similarly, the total reducing power of water extract was found higher than ethanol extract in both potassium ferricyanide reduction (FRAP) and cupric ions reduction capacity methods (CUPRAC). 2,2′-Bipyridine was used to determine the metal chelating activity and the result of water extract was found higher than ethanol extract. Total phenolic and total flavonoid contents of both extracts were studied as well. The values of water extract were found to be higher than that of ethanol extract. The present study found that water extracts of sumac (R. coriaria L.) have effective antioxidant and radical scavenging activities as compared to ethanol extracts.