罗汉果提取液对自由基的清除作用

以邻苯三酚自氧化产生超氧自由基(02-),Fenton反应产生羟自由基(.OH),用分光光度法测定罗汉果提取物对O2-和.OH的清除作用。结果表明,罗汉果提取物对O2-和.0H均有显著清除作用。     

紫菀提取物油脂抗氧化效果研究

对紫菀（Aster tataricus.L.f.）乙酸乙酯提取物（EAE）、丙酮提取物（AE）和乙醇提取物（EE）的油脂抗氧化活性进行研究,用碘量法进行抗氧化性的测定。结果表明,EAE对油脂具有较好的抗氧化作用,在一定范围内,抗氧化效果随添加量的增加而增强,而丙酮及乙醇提取物抗氧化效果不明显。此外,EAE与Vc在花生油中有很好的协同增效作用,表明紫苑具有开发天然抗氧化剂的潜在价值。     

5种中药提取物清除自由基的体外抗氧化活性研究

目的研究建立间接测定中药提取物抗氧化活性的荧光检测新方法。方法利用Fenton反应产生·OH,·OH迅速氧化曙红B使其褪色,荧光强度显著降低,依荧光强度减弱程度间接检测·OH产生量。结果中药提取物具有抗氧化性,可以与·OH反应,使反应体系荧光强度降低。结论 5种中药提取物均具有一定的抗氧化活性,其中以五倍子最佳。     

黄山贡菊提取物对羟自由基清除作用

采用邻二氮菲—Fe(Ⅱ) /H2 O2 体系产生羟自由基(·OH) ,用分光光度法(波长5 36nm)研究了黄山贡菊提取物对·OH的抑制和清除作用。结果表明:黄山贡菊提取物对·OH具有显著的抑制和清除作用。     

亮绿褪色光度法检测Fenton体系产生的羟自由基

基于Fenton反应产生的—OH对亮绿的褪色反应,采用亮绿为指示剂,建立了一种分光光度法测定Fenton反应产生的—OH的方法。优化了体系的反应条件,并用新建立的方法研究了某些抗氧化剂对羟自由基的清除能力。结果表明,用该方法测定得到的各抗氧化剂IC50值所预测的各自的抗氧化能力顺序与文献结果一致。     

简便褪色光度法研究中药及其药对的体外抗氧化活性

目的建立了以罗丹明B(RB)为捕获显色剂的芬顿(Fenton)体系分光光度法,用于检测黄芪白术中药及其药对水提物协同作用对羟自由基(·OH)的抗氧化清除作用。方法在酸性介质中,利用Fenton反应产生的·OH迅速氧化RB使其褪色,在550 nm处测定溶液吸光度的变化,通过RB褪色光度法对芪术药对进行了·OH清除实验。结果芪术单药及其药对提取物对·OH具有很强的清除作用,芪术药对混合提取液在·OH清除能力方面具有显著的协同增效效应。结论该方法简便、灵敏、分析成本低,适于大批量中药抗氧化活性性能的筛选以及中药药对抗氧化清除率的定量检测。     

木蝴蝶黄酮粗提物体外抗氧化活性研究

用乙醇作为提取溶剂,有效提取木蝴蝶中黄酮类化合物,并体外分析其抗氧化活性。采用DPPH自由基清除活性、Fenton反应和邻苯三酚氧化法,测定该粗提物对不同自由基的清除能力;并用MTT实验法检测该提取物,对过氧化氢诱导的氧化损伤内皮和心肌细胞的保护作用。木蝴蝶中黄酮提取物对O-2·、·OH、DPPH·有较强的清除能力,并具有明显抗过氧化氢氧化损伤和恢复细胞活性的作用。     

松针乙醇提取物体外抗油脂氧化活性测定

以油脂为抗氧化基质,用碘-淀粉比色法测定计算油脂氧化POV值,观察马尾松松针乙醇提取物的体外抗氧化活性。松针乙醇提取物加入油脂,置65℃恒温烘箱,以枸橼酸为阳性对照,每隔24 h测定计算油脂氧化POV值。结果显示,松针乙醇提取物能明显减缓油脂POV值升高趋势,且具有一定的时间和浓度依赖性,提示松针乙醇提取物具有抗氧化活性。     

朱砂七总鞣质的提取及抗氧化活性研究

考察了朱砂七总鞣质的含量及抗氧化活性.以60%丙酮为溶媒提取朱砂七鞣质,用铁氰化钾还原法测鞣质的还原能力,以Fenton反应为产生·OH模型,以邻苯三酚自氧化反应为产生O2-·模型,用分光光度法测定鞣质对模型中产生的·OH和O2-·的清除作用.结果表明朱砂七鞣质的还原力随浓度的增大而增大,朱砂七鞣质对O2-·和·OH的...     

茶多酚及其氧化产物清除不同体系产生的活性氧自由基的分光光度法研究

用分光光度法测定了茶多酚及其氧化产物对不同体系产生的活性氧自由基O2· - 和·OH的清除作用。结果表明 :对由光照核黄素体系产生的O2· - ,在试验质量浓度范围 ( 8 3～ 1 67ug mL)内茶多酚及其氧化产物的最大清除率分别为 96 6%和 92 1 %。对由 2 脱氧 D 核糖体系产生的·OH ,在实验质量浓度范围 ( 5～ 80 0ug mL)内茶多酚及其氧化产物的最大清除率分别为83 4%和 88 5%。茶多酚氧化产物 ,SOD粗酶液 ,茶多酚对邻苯三酚自氧化产生的O2· - 均表现出较强的抑制作用 ,抑制率分别为 66 5% ,47 6% ,45 3%。茶多酚及其氧化产物与SOD有显著的协同增效作用 ,但氧化产物的效果强于茶多酚。     

马铃薯皮中多酚类物质的抗氧化性研究

通过体外抗氧化体系测定马铃薯皮多酚的抗氧化活性。除超氧阴离子的能力;马铃薯皮多酚清除羟基自由基的能力;马铃薯皮多酚清除DPPH自由基的能力;马铃薯皮多酚对油脂的抗氧化能力。马铃薯皮多酚对超氧阴离子的清除率最高达18.33%,且在低浓度清除能力明显高于同浓度抗坏血酸(Vc);马铃薯皮多酚对羟基自由基的清除率最高达92.26%。对DPPH自由基清除率最高达86.08%。油脂中添加马铃薯皮多酚提取液,可以明显降低油脂的过氧化值(POV)。马铃薯皮多酚对超氧阴离子,羟基自由基和DPPH自由基都有很好的清除效果,且在一定程度上降低油脂过氧化值随时间而延长的程度,是很好的天然抗氧化剂。     

橙皮中生物类黄酮的分离纯化工艺研究

橙皮中含有陈皮甙属二氢黄酮类,它最显着的作用是具有抗氧化性,因此可将其提纯后加入到食品中,制成具有抗自由基的功能性食品.     

橙皮中生物类黄酮的分离纯化工艺研究

橙皮中含有陈皮甙属二氢黄酮类,它最显着的作用是具有抗氧化性,因此可将其提纯后加入到食品中,制成具有抗自由基的功能性食品.     

海滩植物厚藤（Ipomoea Pes-caprae）抗氧化活性研究

采用加速溶剂萃取技术(ASE)快速制备厚藤活性提取物,并以DPPH法对厚藤茎叶不同溶剂提取物抗氧化活性进行评价。抗坏血酸抗氧化能力乙酸乙酯提取物抗氧化能力乙醇提取物抗氧化能力甲醇提取物抗氧化能力石油醚提取物抗氧化能力,其IC50值分别为0.203 4、0.836 2、0.868 8、1.867 5、6.628 3 g/L。结果显示,厚藤茎叶提取物具有一定的抗氧化活性,且以乙酸乙酯为提取溶剂时,效果最佳。     

超声波辅助酶解法提取桔皮中果胶的工艺研究

文章采用超声波辅助酶解法提取桔皮中的果胶,研究了pH、提取温度及提取时间对果胶提取率的影响,确定了提取的最佳工艺条件：pH 4.6,提取温度41℃,提取时间50 min。在最佳提取工艺条件下,桔皮中果胶的提取率约为2.08%。     

Bioactive Compounds,Antioxidant Activities and Heat Stability of Corn Oil Enriched with Tunisian Citrus aurantium L. Peel Extract

This study was designed to examine physicochemical composition, antioxidant activities and heat stability of corn oil enriched with bitter orange peel. Volatile compounds composition of corn oil flavored with Citrus aurantium peel was investigated. Flavored oil total aroma content (2.6 mg/mg oil) was mainly represented by monoterpene hydrocarbons and limonene was the major one (2.49 mg/mg oil). Flavored oil methanolic extract was characterized by total phenol content of 1.22 mg GAE/kg. Chlorogenic, ferulic and p-coumaric acids were the major phenolic components of the flavored oil extract (34.33, 30.24 and 19.39 %, respectively). It was also characterized by a higher chlorophylls and carotenoids contents than the refined one. Antioxidant activities of methanolic extracts of both samples were determined using four assays: DPPH, reducing power, β-carotene bleaching and metal chelating tests. In β-carotene bleaching and DPPH radical scavenging assays, flavored oil methanolic extract showed higher activities than the control. It was characterized by a total antioxidant activity of 4.08 mg GAE/kg and an EC₅₀ value of 3.14 mg/mg oil. Its concentration providing 50 % inhibition (IC₅₀) was 0.53 mg/mg oil in the DPPH test and 4.08 mg/mg oil in the β-carotene bleaching test. However, refined corn extract showed significantly lower antioxidant activities (p < 0.05). Results of the oxidative stability index showed bitter orange peel effectiveness against thermal oxidation based on the increased induction time observed in flavored oil (5.95).     

Antioxidant activities of hot water extracts from various spices

Recently, the natural spices and herbs such as rosemary, oregano, and caraway have been used for the processing of meat products. This study investigates the antioxidant activity of 13 spices commonly used in meat processing plants. The hot water extracts were then used for evaluation of total phenolic content, total flavonoids content and antioxidant activities. Our results show that the hot water extract of oregano gave the highest extraction yield (41.33%) whereas mace (7.64%) gave the lowest. The DPPH radical scavenging ability of the spice extracts can be ranked against ascorbic acid in the order ascorbic acid > clove > thyme > rosemary > savory > oregano. The values for superoxide anion radical scavenging activities were in the order of marjoram > rosemary > oregano > cumin > savory > basil > thyme > fennel > coriander > ascorbic acid. When compared to ascorbic acid (48.72%), the hydroxyl radical scavenging activities of turmeric and mace were found to be higher (p < 0.001). Clove had the highest total phenolic content (108.28 μg catechin equivalent (CE)/g). The total flavonoid content of the spices varied from 324.08 μg quercetin equivalent (QE)/g for thyme to 3.38 μg QE/g for coriander. Our results indicate that hot water extract of several spices had a high antioxidant activity which is partly due to the phenolic and flavonoid compounds. This provides basic data, having implications for further development of processed food products.     

Chemical composition and bioactive compounds of flour of orange (Citrus sinensis), tangerine (Citrus reticulata) and grapefruit (Citrus paradisi) peels cultivated in Venezuela

The purpose of this research was to evaluate the chemical composition and some bioactive compounds in the peel's flour of some of the most consumed citrus fruits cultivated in Venezuela. Chemical composition as well as some trace elements, ascorbic acid, carotenoids dietary fiber, total polyphenols and their antiradical efficiency, using the 2,2-diphenyl-1-picrylhidracyl (DPPH) were assessed in the dried peels of orange (Citrus sinensis), tangerine (Citrus reticulata) and white grapefruit (Citrus paradisi). Moisture, fat, protein and ash content for all samples showed statistical differences (p < 0.05). Tangerine's peel showed the highest magnesium and carotenoid content, while highest ascorbic acid and carotenoid content was found in the grapefruit's peel. Dietary fiber content presented significant high value in the tangerine peel. All samples presented high content of extractable polyphenols (4.33; 7.6 and 5.1 g/100g). The highest antiradical efficiency was shown by the tangerine's peel, value which correlates with the polyphenol content. These results suggest that tangerine peel should be the most suitable, to reduce risk of some diseases such as cardiovascular and some associated to lipid oxidation. Studied samples are good sources of dietary fiber and phenolic compounds, whose use could be useful in the formulation of functional foods, taking advantage of the presence of dietary fiber and antioxidant compounds in only one ingredient.     

Changes in Lipid Composition and Antioxidant Capacity of Bitter Orange (<Emphasis Type="Italic">Citrus aurantium.</Emphasis> L) and Mandarin (<Emphasis Type="Italic">Citrus reticulata.</Emphasis> Blanco) Oilseeds on Different Stages of Maturity

Oilseeds from bitter orange and mandarin and its antioxidant activities were investigated in this study. The effects of harvesting times (D1: green color, D2 yellow color, D3: orange color) on the extraction yield of oilseed were studied. The maximum yield of 44% was achieved at D3 (bitter orange). The chemical composition of the oilseed was analyzed by gas chromatography (GC). The main methyl esters were linoleic acid (C18:2, 32–42%), palmitic acid (C16:0, 22–26%)), stearic acid (C18:0, 9.01%) and linolenic acid (C18:3, 4–10%). The antioxidant activity of oilseed was assessed by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and β-carotene bleaching test. Both methods demonstrated notable antioxidant activities of bitter orange and mandarin oilseeds, which is nearly comparable to the references ascorbic acid and butylated hydroxytoluene (BHT). The antioxidant activities of the oilseeds were also found to be harvesting time-dependent.     

Polyphenolic Contents and Antioxidant Potential of Stem Bark Extracts from Jatropha curcas (Linn)

We assessed the polyphenolic contents and antioxidant potential of the aqueous, ethanol and methanol stem bark extracts of Jatropha curcas. The total phenol, flavonoids, flavonols and proanthocyanidin contents of the extracts were evaluated to determine their effect on the antioxidant property of this plant, using standard phytochemical methods. The antioxidant and free radical scavenging activity of ethanol, methanol and aqueous extracts of the plant were also assessed against 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing, nitric oxide (NO), superoxide anion, (O(2) (-)) and hydrogen peroxide (H(2)O(2)) using spectroscopic methods and results were compared with that of butylated hydroxyl toluene (BHT) and ascorbic acid as standards. The concentrations of different classes of phenolic compounds were higher in methanol and ethanol extracts compared to aqueous extracts. There was correlation between total phenol, total flavonoids, total flavonol and total proanthocyanidins (r = 0.996, 0.978, 0.908, and 0.985) respectively. There was correlations between the amount of phenolic compounds and percentage inhibition of DPPH radicals scavenging activity of the extract (r = 0.98). Findings from the present study indicated that J. curcas is a potential source of natural antioxidants and may be a good candidate for pharmaceutical plant based products.