Antioxidant and free radical scavenging activities of phenols from onion (Allium cepa)

Four (red, violet, white and green) varieties of Allium cepa were studied for their total phenolic contents (TPC), antioxidant (AOA) and free radical scavenging activities (FRSA). The TPC varied from 4.6 to 74.1 mg/g GAE, AOA varied from 13.6% to 84.1% and FRSA showed wide range in terms of IC₅₀ (inhibitory concentration) from 0.1 to 15.2 mg/ml, EC₅₀ (efficient concentration) from 4.3 to 660.8 mg/mg and ARP (antiradical power) from 0.15 to 23.2. The outer dry layers of red and violet varieties showed better inhibition of lipid peroxidation assayed by ammonium thiocyanate than α-tocopherol. The non-site-specific inhibition of hydroxyl radical induced deoxyribose degradation was also higher in the outer dry layers of red and violet varieties than in their middle and inner layers. The outer layers were also potential inhibitors of nitroblue tetrazolium chloride (NBT) reduction caused by superoxide anions. On the other hand the ferrous ion chelating capacity of the red and violet varieties was highest in the inner layers. Specific phenolic composition performed through HPLC and LC–MS/MS showed the presence of gallic acid, ferulic acid, protocatechuic acid, quercetin, and kaempferol. The unutilised outer layers of the red variety were a rich source of quercetin (5110 μg/g) with high AOA, FRSA and also showed significant protection of DNA damage caused by free radicals.     

黑米花青苷胶囊体外清除自由基及抗氧化作用的研究

利用Fenton反应产生羟自由基、邻苯三酚在微碱条件下自氧化产生O-2、磷钼络合物法分别研究了黑米花青苷胶囊和黑米色素对羟基自由基、超氧阴离子的抑制和其总抗氧化活性。结果表明黑米花青苷胶囊和黑米色素能有效清除自由基,具有良好的抗氧化作用。其中黑米花青苷胶囊和黑米色素对羟自由基、超氧阴离子的抑制和其总抗氧化活性随着样品浓度增高而增加。黑米色素对羟自由基、超氧阴离子的抑制和总抗氧化活性显著高于黑米花青苷胶囊。     

Chemical composition and free radical scavenging activities of a sulphated polysaccharide extracted from abalone gonad (Haliotis Discus Hannai Ino)

Crude polysaccharides (CPs) were prepared from Haliotis Discus Hannai Ino gonad by protease-hydrolysis combining boiling-methanol extraction. They were purified to homogeneity by gel-filtration chromatography on Sephacryl-S 100 and Sephacryl-S 200, and semi-preparation high performance liquid chromatography (semi-RP-HPLC) equipped with a SOURCE 30Q anion exchange column. The sulphated polysaccharide obtained, named as PAGP, has an average molecular weight (MW) of 12.5 kDa determined by HPLC coupled to a TSK-gel G4000PW_XL column. Chemical composition analysis indicated it was composed of carbohydrate (50.7%), sulphated group (31.1%), aminohexose (7.1%), aronic acid (6.2%) and protein (2.0%). The carbohydrate part of PAGP was composed of rhamnose (Rha), fucose (Fuc), and galactose (Gal) in molar ratio of 1.0:1.6:2.3. The protein part of PAGP contained 13 kinds of amino acids. Antioxidant assays demonstrated that PAGP possessed stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical scavenging activities than positive controls vitamin C (VC) and vitamin E (VE).     

Antioxidant and free radical scavenging activities of whole wheat and milling fractions

The effects of milling on the phenolic content and antioxidant capacity of two wheat cultivars, namely CWAD (Canadian Western Amber Durum; Triticum turgidum L. var. durum) and CWRS (Canadian Western hard red spring; Triticum aestivum L.) were studied. The milling of wheat afforded several fractions, namely bran, flour, shorts and feed flour. In addition, semolina was the end-product of durum wheat milling. Among different milling fractions the bran had the highest phenolic content while the endosperm possessed the lowest amount and this was also reflected in free radical and reactive oxygen species (ROS) scavenging capacity, reducing power and iron (II) chelation capacity of different milling fractions in the two cultivars. This study demonstrated the importance of bran in the antioxidant activity of wheat, hence consumption of whole wheat grain may render beneficial health effects.     

食用委陵菜黄酮的抗氧化性及清除自由基能力研究

从总体抗氧化能力、对Fe2+诱发卵黄脂蛋白PUFA过氧化体系的抑制能力、清除羟基自由基能力、清除超氧阴离子自由基能力、清除DPPH自由基能力五个方面评价了四种委陵菜中黄酮类化合物的活性,并与其他的合成抗氧化剂VC和PG进行了比较。实验结果表明,在一定浓度范围内,四种委陵菜中黄酮类化合物在上述前四个方面的性能有着固定的顺序:三叶（福建）>三叶（河北）>西南（河北）>西南（福建）,但在清除DPPH自由基方面,其强弱顺序为:西南（福建）>三叶（河北）>西南（河北）>三叶（福建）,且与VC和PG相比,清除DPPH自由基的能力相差无几。      

肉桂精油抗氧化性能及清除自由基能力的研究

对肉桂精油(CEO)的抗氧化和清除游离基活性的比较是基于总体抗氧化能力、清除超氧阴离子自由基能力、清除羟基自由基能力、抗亚油酸脂质过氧化能力、清除DPPH自由基5个方面,并与其他的合成抗氧化剂如BHT、PG做比较。实验结果表明,在一定浓度范围内,CEO的羟自由基清除能力强于BHT和PG;清除超氧阴离子自由基的能力强于PG;清除DPPH自由基能力、抗氧化活性比BHT和PG弱;CEO抑制亚油酸的过氧化能力比BHT和PG略弱。实验表明了CEO在某些方面具有良好的抗氧化效果。     

月桂精油抗氧化性能及清除自由基能力的研究

文章对月桂精油(LEO)的抗氧化和清除游离基活性的比较是基于总体抗氧化能力、清除超氧阴离子自由基能力、清除羟基自由基能力、抗亚油酸脂质过氧化能力、清除DPPH自由基五个方面,并与其它的合成抗氧化剂如BHT、PG做比较.实验结果表明,在一定浓度范围内,LEO的抗氧化活性、羟自由基清除能力、清除DPPH自由基能力强于BHT和PG;清除超氧阴离子自由基的能力弱于PG;精油抑制亚油酸的过氧化能力与BHT和PG相当.实验表明了LEO具有良好的抗氧化效果.     

The phenolic constituents and free radical scavenging activities of Gynura formosana Kiamnra

Gynura formosana Kiamnra (Compositae) is a herbal folk medicine that is a popular vegetable in Taiwan. The free‐radical scavenging activities of a 70% aqueous acetone extract from the herb G formosana were evaluated. Bioassay‐guided fractionation, column separation on Diaion, Toyopearl HW 40(C), Sephadex LH‐20 and MCI CHP20P, and high‐performance liquid chromatography (HPLC) were used to isolate for the first time in G formosana four potent phenolics [caffeic acid ( I ), quercetin 3‐O‐rutinoside ( II ), kaempferol 3‐O‐rutinoside ( III ) and kaempferol 3‐O‐robinobioside ( IV )]. The IC₅₀ values of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity for compounds I – IV were 6.7, 7.7, 300.3 and 286.7 µM , respectively, and, for superoxide radical scavenging activity, they were 187.3, 25.8, 55.3 and 87.4 µM , respectively. Using a spin trapping electron spin resonance (ESR) method, caffeic acid ( I ) and quercetin 3‐O‐rutinoside ( II ) exhibited good hydroxyl radical activity. The free radical scavenging activity of G formosana phenolics may improve the economic value of this herb and assist in its development as a health food. Copyright © 2004 Society of Chemical Industry     

调味香料草果挥发油的抗氧化性能及清除自由基能力

利用水蒸气蒸馏法提取了调味香料草果的挥发油,产率为1.62%。从总体抗氧化能力、清除超氧阴离子自由基能力和清除羟基自由基能力三个方面,测定了该挥发油的抗氧化活性,并与合成抗氧化剂没食子酸丙酯(PG)做了比较。实验结果表明,在一定浓度范围内,草果挥发油清除超氧阴离子自由基的能力和清除羟基自由基的能力均强于PG。从而说明草果挥发油具有良好的抗氧化效果。     

天然调味香料众香子精油的抗氧化性能及清除自由基能力研究

文章研究了众香子精油的总体抗氧化能力、清除超氧阴离子自由基能力、清除羟基自由基能力,并与合成抗氧化剂没食子酸丙酯(PG)进行了比较。实验结果表明,在一定浓度范围内,众香子精油清除超氧阴离子自由基的能力和清除羟基自由基的能力均强于PG。从而说明众香子精油具有良好的抗氧化效果。     

Antioxidant and antibacterial activities of various seabuckthorn (Hippophae rhamnoides L.) seed extracts

Seabuckthorn (Hippophae rhamnoides L.) seeds were successively extracted with chloroform, ethyl acetate, acetone and methanol (MeOH) using a Soxhlet extractor for 8 h each. The crude extracts were screened for antioxidant and antibacterial activities. The reducing power and antioxidant activities evaluated in various in vitro models (1,1-diphenyl-2-picrylhydrazine and liposome model system) showed the highest activity for MeOH extract. The MeOH extract was also found to posses maximum antibacterial activity. The MIC values, with respect to MeOH extract for Bacillus cereus, Bacillus coagulans, Bacillus subtilis, Listeria monocytogenes, Yersinia enterocolitica, were found to be 200, 300, 300, 300, and 350 ppm, respectively. These results indicated the possibility of using seabuckthorn seeds for medicinal uses and food preservation.     

Antioxidant and free radical scavenging activities of pigments extracted from molasses alcohol wastewater

The pigments from molasses alcohol wastewater were extracted by the macroporous resin adsorption method. The antioxidant and free radical scavenging activities of these pigments were also investigated. The adsorptive characteristics of five macroporous resins including HPD-600, HPD-500, D301-R, NKA-II and D296-R were studied and the results showed that the macroporous resin HPD-600 was most appropriate for extracting the pigments from molasses alcohol wastewater. The antioxidant and free radical scavenging activities of pigments extracted from alcohol wastewater were evaluated using nitrate, hydroxyl radical, superoxide anion radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) in vitro model systems. The pigment extract exhibited a concentration-dependent radical scavenging activity in all the systems. Meanwhile, scavenging activity of pigment extract in the DPPH system was found to be significantly (P < 0.05) higher than that in other systems and the 50% inhibitory concentration (IC₅₀ value) was about 0.07 mg/ml. The scavenging effect of pigment extract on superoxide anion radical was very weak with IC₅₀ value greater than 10 mg/ml.     

染料木素乙酰阿魏酸酯抗氧化及清除自由基活性研究

采用几种化学及生物学模型考察了染料木素乙酰阿魏酸酯的清除自由基能力、螯合金属离子能力及保护DNA免受自由基损伤能力.研究结果表明,染料木素酯化修饰物比染料木素具有更强的清除DPPH·、·OH自由基的能力,且保护DNA免受羟基自由基损伤的能力与染料木素相当,但染料木素酯化修饰物比染料木素螯合金属Fe2+离子的能力有一定程度的减弱.此外,本文还探讨了酯化产物与其抗氧化及清除自由基活性之间的构效关系,为寻求与自由基相关疾病新药的发现、食用功能因子的开发等奠定实验基础.     

酵母源金属硫蛋白体外清除自由基及抑菌活性的研究

目的:比较两种异构体形式酵母源金属硫蛋白与动物源金属硫蛋白体外清除自由基及抑菌活性。方法:以VC为对照,分光光度法测定金属硫蛋白对自由基清除率,以金黄色葡萄球菌、大肠杆菌和李斯特氏菌为指示菌,研究金属硫蛋白对致病菌的抑制作用。结果:金属硫蛋白对羟基自由基及DPPH自由基清除能力明显强于VC,但对超氧阴离子自由基的清除效果却低于VC,金属硫蛋白对金黄色葡萄球菌、李斯特氏菌具有一定的抑制作用。金属硫蛋白清除自由基关系为Zn-MT>MT-Ⅰ>MT-Ⅱ。结论:金属硫蛋白具有较强的清除自由基能力,对部分致病菌具有一定的抑制作用,作用效果因金属硫蛋白来源、纯度及构型而不同。      

麦麸膳食纤维抗氧化和·OH自由基清除活性的研究

从麦麸中分离得到的水溶性和水不溶性膳食纤维具有抗氧化活性和·ＯＨ自由基清除能力，两者对·ＯＨ的清除率分别为８０．２％和５８．３％。     

油茶叶黄酮类化合物清除自由基及抑菌作用研究

以油茶叶为原料,测定其黄酮类化合物对羟自由基和超氧自由基清除能力;并对常见食品腐败菌及部分致病菌抑制特性进行探讨.研究结果表明,黄酮类化合物对羟自由基和超氧自由基具有较好清除效率,清除率均在59％以上;黄酮类化合物对部分食品腐败菌和致病菌具有一定抑制作用;当黄酮浓度达2.5 mg/mL时,对试验菌种呈现明显抑制作用.     

金边瑞香提取物抗氧化及清除自由基活性研究

采用不同的化学模型评价了金边瑞香(Daphne odora var.marginata)乙醇提取物的乙酸乙酯组分(EA)及其三个子组分(乙酸乙酯组分上硅胶柱层析,用石油醚-丙酮按照体积比为8:3、4:3和1:4梯度洗脱得到,分别命名为F1、F2和F3)的抗氧化及清除自由基的能力.研究结果表明,组分F2清除超氧自由基和羟基自由基的能力最强,组分F1清除DPPH·的能力最强,EA还原铁离子和螯合亚铁离子的能力最强,所有组分对羟基自由基所致DNA损伤均有很好的保护作用,预测了活性较强的组分F2可能含有活性先导物.     

Proximate composition and free radical scavenging activity of edible fruits from the Argentinian Yungas

The proximate composition and free radical scavenging effect of native food plants gathered in the Argentinian Yungas have been assessed. Some 25 samples were collected for proximate analysis and free radical scavenging effect of their MeOH‐soluble extracts. Total acidity, phenolics and solid content of 16 preserves prepared from native fruits have been determined. The samples belong to 13 different species corresponding to eight plant families, mainly Myrtaceae, Solanaceae and Ulmaceae. The highest organic acid contents (as citric acid) were found in the preserves of Psidium guineense and Cyphomandra betaceae with the lowest in Sideroxylon obtusifolium and Myrciantes pungens. Total phenolics in the preserves ranged from 0.34 g kg^?1 DM in Rhipsalis flocosa to 7.30 g kg^?1 DM in Celtis iguanae. The MeOH‐solubles of the fruits/petioles as well as the preserves were assessed for inhibition of the enzyme xanthine oxidase (XO), decoloration of the free radical 2,2‐diphenyl‐1‐picryl‐hydrazyl (DPPH) and scavenging of the superoxide anion. The highest effect of the solubles towards the DPPH assay was observed for M pungens and Rubus imperialis before processing. None of the samples was effective as a XO inhibitor or superoxide anion scavenger. The best protein sources in our study were the fruits of Carica quercifolia, Celtis iguanae and Sambucus nigra. Copyright © 2005 Society of Chemical Industry     

中国、印度产白豆蔻精油清除自由基能力研究

从总体抗氧化能力、清除超氧阴离子自由基能力、清除羟基自由基能力三个方面,以合成抗氧化剂没食子酸丙酯(PG)作为参照物,分别评价了白豆蔻精油的抗氧化活性,并进一步比较了中国与印度产白豆蔻的抗氧化性能。结果表明:在精油浓度为0.5～2.0mg/mL的浓度范围内,中国、印度产白豆蔻精油清除超氧阴离子自由基的能力强于PG。在1×10-5～5×10-5mg/mL的浓度范围内,中国、印度产精油清除羟基自由基的能力强于PG。从而说明白豆蔻精油具有良好的抗氧化效果,且印度产白豆蔻精油抗氧化性略强于中国产白豆蔻精油。     

Thermal characteristics,chemical composition and polyphenol contents of date-pits powder

Polyphenol contents in date-pits varied from 21–62 mg gallic acid equivalents (GAE)/g date-pits when acetone–water, ethanol–water, methanol–water and water alone were used as solvents for extraction at temperatures 22, 45, and 60 °C. The BET and GAB monolayer values of date-pits were estimated as 4.3 and 4.1 g/100 g dry-solids. The DSC thermogram of freeze-dried date-pits showed an endothermic peak due to the melting of oil, and a second endothermic peak for solids-melting (i.e. non-fat). The first shift indicated the glass transition (i.e. T_g) while the second exothermic shift after solids-melting indicated the interactions of the components in melted solids. The melting peak temperature was decreased due to the plasticization of solids with water and the melting enthalpy was increased with the increasing water content due to the formation of more order in the amorphous, semi-crystallites and crystallites parts. The Flory–Huggins modelling of peak temperature estimated the water–solids interaction parameter as 0.0068. The melting peak temperature increased exponentially with increasing heating rate and the data was fitted with Mehl–Johnson–Avrami and Kissinger models. Annealing close to the onset of melting indicated that melting peak temperature increased exponentially with increasing annealing time, while melting enthalpy decreased with the increasing annealing time.