Radical scavenging activity of canola hull phenolics

Possible use of canola hulls as a source of natural anti-oxidants was explored. Cyclone canola hulls were extracted with methanol (30 to 80%, vol/vol) and acetone (30 to 80%, vol/vol). The free radical-scavenging activity of phenolic extracts so prepared was evaluated using the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical ion (ABTS^o−), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and chemiluminescence assays. The total content of phenolics in prepared extracts from canola hulls ranged from 15 to 136 mg sinapic acid equivalents per gram of extract. Higher levels of condensed tannins were detected in the acetone extracts than in the corresponding methanolic counterparts. Seventy and 80% (vol/vol) acetone extracts displayed markedly stronger antioxidant activity than any of the other extracts investigated. Statistically significant linear correlations were found between TEAC (Trolox equivalent antioxidant capacity) values (expressed in mM of Trolox equivalents per gram of extract) and total pehnolics, TEAC and total condensed tannins (i.e., determined using the modified vanillin and pronthocyanidin assays), as well as TEAC and protein precipitation activity of phenolic extracts (i.e., measured using the dye-labeled assay). The antioxidant activities of extracts as determined by the ABTS^o− radical ion assay correlated highly with those of the chemiluminescence and DPPH radical assays.     

山楂酒甲醇含量的测定及清除DPPH和ABTS自由基活性的研究

建立了山楂酒中甲醇测定的GC分析方法,并对清除DPPH和ABTS自由基活性进行了研究。结果表明:山楂酒在发酵9~425 d时,其甲醇含量呈逐渐上升的趋势,在564~730 mg/L之间。山楂酒具有较强的DPPH和ABTS自由基活性的能力。随着时间的延长,山楂酒DPPH·和ABTS+·清除能力呈下降趋势。     

Effect of cooking on total vitamin C contents and antioxidant activity of sweet chestnuts (Castanea sativa Mill.)

In this work the total vitamin C contents (ascorbic acid + dehydroascorbic acid) and antioxidant activity of raw and cooked chestnuts was evaluated. The vitamin C contents of raw chestnuts varied significantly between the different cultivars (cv) studied and it varied from 400 mg/kg dry weight (cv Lada) to 693 mg/kg dry weight (cv Martaínha). The different cultivars behave differently during the cooking process concerning the loss of vitamin C. A significant decrease in the vitamin C content of the chestnuts was observed, 25–54% for the boiling process and 2–77% for the roasting process. Boiled and roasted chestnuts can be good sources of vitamin C since it may represent 22.4%, 16.2%, 26.8% and 19.4%, respectively, of the recommended dietary intake for an adult man and woman. The cooking process significantly changed the antioxidant activity of the chestnuts. A difference was observed between the cultivars during the cooking processes, concerning the antioxidant activity. For the raw chestnuts the variation in vitamin C content of the chestnuts explains 99% of the antioxidant activity variation but for the roasted and boiled chestnuts this percentage significantly decreases to 51% and 88%, respectively. Although a high antioxidant activity is still present in the cooked chestnuts, the cause for this antioxidant activity is less dependent on the vitamin C content of the chestnuts, probably due to the conversion of ascorbic acid to dehydroascorbic acid. The increase in gallic acid during the cooking process, presumably transferred from the peels to the fruit, also contributes to the high antioxidant activity observed for the cooked chestnuts.     

反应时间对DPPH·法、ABTS+·法评价抗氧化性结果的影响

由于DPPH·法、ABTS+·法操作简单,不需要特殊的检测设备(通过反应体系颜色的改变评价试样抗氧化性),因此,常被选作抗氧化性能评价方法。用这两种方法进行抗氧化性评价时,通常用固定反应时间下算得的EC50值(自由基清除率为50%时所需试样浓度)表征抗氧化剂的抗氧化性强弱(对于DPPH·法,固定时间为30min;对于ABTS+·法,固定时间为6min),结果表明:不同抗氧化剂因其组成、结构的差异,与DPPH·、ABTS+·反应速率不同,反应到达平衡的时间不同,将反应时间固定在某一值时,可能对抗氧化剂的抗氧化性评价带来错误的判断。     

草菇子实体GC-MS分析及不同极性部位体外抗氧化活性研究

目的:研究草菇乙醇提取物不同极性部分的抗氧化活性及子实体GC-MS分析。方法:用95%的乙醇回流提取草菇,依次用有机溶剂萃取获得石油醚层、氯仿层、乙酸乙酯层、正丁醇层4个不同极性部位。以2,6-二叔丁基对甲酚（BHT）为对照,分别考察其总抗氧化能力、DPPH自由基清除活性、铁离子还原能力、ABTS自由基清除活性,比较草菇乙醇提取物不同极性部位的抗氧化作用。结果:通过GC-MS分析,分析出49个化合物,以烷烃类、脂肪酸类、醛类、酯类、酮类为主,含量分别为22.54%、19.94%、15.38%、13.08%、7.33%。通过四种体外抗氧化能力的测定,草菇乙醇提取物的不同极性部位均有抗氧化活性,其中乙酸乙酯层和正丁醇层表现出较好的抗氧化活性,氯仿层的抗氧化活性最弱。在所设定浓度范围内,其乙酸乙酯层的总抗氧化能力、DPPH自由基清除率、铁离子还原能力明显高于其它层（p<0.05）。在ABTS自由基清除体系中,正丁醇层的ABTS自由基清除率高于乙酸乙酯层,但差异不显著（p>0.05）。结论:通过对草菇子实体GC-MS分析及抗氧化活性测试,草菇提取物的乙酸乙酯层和正丁醇层的抗氧化作用强,是天然抗氧化剂的良好来源,应对其进一步分离纯化。      

广林9号桉叶多酚抗氧化活性研究

采用不同极性有机溶剂对广林9号桉叶提取物进行系统萃取分离,用福林-酚法测定各组分的总酚含量,以1,1-二苯基-2-三硝基苯肼(DPPH)、2,2＇-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)(ABTS)、还原能力3种体外抗氧化活性方法测定了桉叶各组分的抗氧化活性。结果表明,不同萃取组分中,乙酸乙酯组分总酚含量最高,达到502.67mg/g;其对DPPH自由基和ABTS＋·的清除能力和还原能力也最强,优于阳性对照物茶多酚,其清除两种自由基的IC50分别为0.097mg/mL 和0.034mg/mL;通过总酚含量与抗氧化活性比较发现,其抗氧化活性与总酚含量成正相关,由此判断桉叶提取物的抗氧化活性成分主要为多酚类物质;桉叶粗提物中多酚含量达到30%以上,与茶叶粗提物中多酚含量相当,具有开发意义。     

Effects of various solvents on the extraction of antioxidant phenolics from the leaves, seeds, veins and skins of Tamarindus indica L.

The effects of solvents, of varying polarities, on the extraction of antioxidant phenolics from the leaves, seeds, veins and skins of Tamarindus indica (T. indica) were studied. The efficiencies of the solvents for extraction of the antioxidant phenolics were in the order: methanol > ethyl acetate > hexane. Phenolic content ranged from 3.17 to 309 mg of gallic acid equivalents/g. Methanol leaf extract (MEL) had the highest phenolic content and was the most potent scavenger of DPPH and superoxide radicals. Methanol vein extract had the highest ferric reducing activity whereas methanol seed extract was the most potent ABTS radical-scavenger. A positive correlation existed between phenolic content and antioxidant activities of the plant parts. HPLC analyses of MEL revealed the presence of catechin, epicatechin, quercetin and isorhamnetin. Overall, methanol was the most effective solvent for extraction of antioxidant phenolics from T. indica. T. indica, particularly the leaf, can be a useful source of natural antioxidants.     

无梗五加叶体外抗氧化活性研究

研究无梗五加叶及其不同部分的抗氧化活性,研究其作为食用天然抗氧化剂的可行性.采用DPPH·、ABTS·+自由基及还原性反应体系,利用分光光度法测定无梗五加叶总提液及其不同组分在不同浓度下的抗氧化能力和总酚含量.结果表明:无梗五加叶的不同部分对DPPH·、ABTS·+自由基均具有较强的清除能力,对Fe3+有较强的还原能力...     

Changes in Phenolic Content and Antioxidant Activity of Italian Extra‐Virgin Olive Oils during Storage

ABSTRACT: Phenolic composition and antioxidant activity of extra‐virgin olive oils extracted from several Italian varieties were studied at production and during storage. The antioxidant activity was measured according to the following tests: in the aqueous phase, by radical scavenging of the 2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulfonic acid) (ABTS) radical cation; and in the lipid phase, using the β‐carotene bleaching method. The phenolic content was not correlated to the oxidation indices (peroxide value and spectrophotometric constants). The phenolic contents and profiles of the various cultivars showed remarkable differences. The phenolic content was strongly correlated with the antioxidant activity measured according to the β‐carotene test and weakly correlated with the radical scavenging ability.     

Cultivar differences of total anthocyanins and anthocyanidins in red and purple-fleshed potatoes and their relation to antioxidant activity

Total anthocyanins (TAC) and individual anthocyanidins (AN) after hydrolysis were measured in 15 red and purple-fleshed potato cultivars produced in five different locations in the Czech Republic and a new cultivar Blaue St. Galler from Switzerland. It was found that TAC, expressed as cyanidin content, varied between 0.7 mg 100 g⁻¹ FW (cv. Blue Congo) and 74.3 mg 100 g⁻¹ FW (cv. Blaue Ludiano). Major differences in cultivars were found for AN relative abundance. For cv. Highland Burgundy Red a high proportion of pelargonidin (98.7%) was characteristic, whereas cv. British Columbia Blue contained almost exclusively cyanidin. Cultivars Violette and Vitelotte showed a relatively high content of malvidin. Cultivar Shetland Black differed from others with its higher content of peonidin (on average 36.7%). High petunidin abundance in the cultivars Valfi, Blue Congo, Salad Blue, Blaue St. Galler, Blaue Hindel Bank, Blaue Ludiano, Blaue Schweden, Farbe Kartoffel and Salad Red was found. TAC and AN contents highly corresponded with antioxidant activity (AA) determined with the ABTS, FRAP and DPPH assays in vitro. High AA was shown by the cultivars Vitelotte, Violette, Blaue Ludiano, Hafija, and Highland Burgundy Red. Increased height above sea level, higher annual sum of precipitation, and lower annual average temperatures caused higher AA and TAC. A high degree of hydroxylation and/or methoxylation of individual anthocyanidins could contribute in conjunction with other phenolics to high AA (peonidin, delphinidin and malvidin in the cultivars Blue Congo, Highland Burgundy Red and Shetland Black). Consequently, new red and purple-fleshed cultivars with high TAC and highly methoxylated and/or hydroxylated AN could be a promising source of favourable antioxidants in human nutrition.