硬脂酰氯改性对核桃青皮多酚纯化物抗氧化功效的影响

通过对比核桃青皮多酚纯化物及其硬脂酰氯改性产物的还原力、体外清除自由基能力以及抗油脂氧化能力,分析硬脂酰氯改性对核桃青皮多酚纯化物抗氧化功效的影响。结果表明:核桃青皮多酚纯化物具有较强的抗氧化能力;在所选的浓度范围中,除了DPPH自由基清除率外,核桃青皮多酚纯化物和改性后的物质的还原力、羟基自由基、ABTS自由基与亚硝酸盐清除能力以及抗油脂氧化能力均大于V_C和BHT;核桃青皮多酚纯化物改性后,其还原力和体外清除自由基能力均低于改性前,但其抗油脂氧化能力比改性前增强。     

红外与微波预处理油茶籽对其原油DPPH自由基清除能力的影响

为了研究油茶籽油氧化稳定性机制,了解不同预处理方式对油茶籽油抗氧化能力的影响,以DPPH自由基清除能力为指标,对油茶籽分别经红外与微波预处理后得到的油茶籽原油及其极性组分和非极性组分抗氧化能力进行分析。结果表明：油茶籽分别经红外和微波预处理后,得到的油茶籽原油及其极性、非极性组分DPPH自由基清除能力变化显著;红外预处理的油茶籽所制油茶籽原油及其非极性组分的DPPH自由基清除能力高于相应微波预处理,其最大值分别高3.53μg/g和6.47μg/g;微波预处理的油茶籽所制油茶籽原油中极性组分的DPPH自由基清除能力最大值比相应红外预处理的高38.77μg/g。油茶籽原油对DPPH自由基的清除能力主要来自其极性组分,非极性组分的DPPH自由基清除能力弱于极性组分。     

核桃分心木提取物的抗氧化活性及其对油脂氧化稳定性的影响

为充分利用核桃副产品资源,该研究采用超声辅助乙醇提取核桃分心木抗氧化活性成分,初步研究核桃分心木提取物的抗氧化活性。根据DPPH自由基清除能力和总酚、总黄酮含量测定结果,对核桃分心木的不同浓度乙醇溶液提取物及4种不同极性溶剂萃取物进行抗氧化活性评价。测定正丁醇萃取物DPPH自由基、ABTS+自由基和羟基自由基的清除能力,并以菜籽油为底物,研究该萃取物对菜籽油氧化稳定性的影响。结果表明：核桃分心木60%乙醇溶液提取物抗氧化活性较高,且抗氧化活性较强的物质主要集中在正丁醇萃取相。正丁醇萃取物DPPH自由基、ABTS+自由基清除能力的IC50值均为0.010 mg/mL。油脂氧化稳定性大小顺序依次为0.02%特丁基对苯二酚>0.05%正丁醇萃取物>0.04%正丁醇萃取物>0.03%正丁醇萃取物>0.02%VC>0.02%正丁醇萃取物>0.01%正丁醇萃取物>空白对照。添加0.04%正丁醇萃取物的油脂,其抗氧化活性与添加0.02%VC相当。说明核桃分心木提取物具有较好抗氧化活性,可作为天然抗氧化活性物质的良好资源。     

蜂胶不同溶剂萃取物组成和抗氧化性的研究

以蜂胶为原料,分别以甲醇、乙醇、氯仿、蒸馏水为溶剂进行萃取,测定各萃取物总酚与黄酮类物质的含量,通过测定还原能力,清除DPPH 自由基能力的测定来比较4 种不同萃取物的抗氧化性。结果表明：甲醇萃取物具有较强的抗氧化性。甲醇萃取物浓度为0.25mg/ml 时还原力高达1.162,且浓度为0.05mg/ml 时对DPPH 自由基清除率为64.676%。乙醇萃取物通过石油醚、氯仿、乙酸乙酯、丙酮依次分级萃取后所得到4 种萃取物各项指标测定结果表明,氯仿萃取了蜂胶乙醇萃取物中主要成分,但乙酸乙酯和丙酮萃取物的还原能力及清除DPPH 自由基清除能力较佳,在浓度为0.05mg/ml 时还原力分别为2.087 和1.798,DPPH自由基清除率达87.724% 和88.013%。     

植物油甲醇萃取物的自由基清除能力及其与多酚、生育酚含量的相关性

研究评估10种常见植物油甲醇萃取物的ORAC、FRAP、ABTS和DPPH自由基清除能力,并将自由基清除能力与多酚、生育酚含量进行相关性分析。结果表明:所有样品对4种自由基平均清除能力依次为FRAPORACABTSDPPH;各种植物油甲醇萃取物清除不同自由基的能力不同,芝麻油甲醇萃取物的ORAC清除能力最强,高达1 187.43μmol TE/100 g;植物油多酚含量较生育酚含量与其甲醇萃取物的自由基清除能力具有更好的相关性,ORAC和ABTS自由基清除能力与植物油多酚含量在P0.01水平上呈显著相关,相关系数分别达0.819和0.946;DPPH和FRAP自由基清除能力与植物油多酚、生育酚含量均在P0.05水平显著相关。     

石榴皮分级提取物的抗氧化性能比较

研究比较四段分级提取石榴皮多酚产物的体外抗氧化活性的差异,并与VC进行了比较。结果表明:各级石榴皮多酚提取物都具有较强的清除自由基的能力,它们清除三种自由基的能力由大到小为:ABTS+自由基DPPH·自由基·OH自由基。石榴皮多酚粗提物经大孔树脂纯化以及乙酸乙酯萃取后,多酚含量提高,清除自由基的能力增强。各阶段产物对三种自由基的清除能力强弱顺序均为:乙酸乙酯相萃取物树脂纯化物水相保留物VC粗提物,它们的总抗氧化能力强弱顺序为:VC乙酸乙酯相萃取物树脂纯化物水相保留物粗提物,它们的还原能力强弱顺序为:乙酸乙酯相萃取物树脂纯化物VC水相保留物粗提物。这些结果说明:经过粗提、树脂纯化及乙酸乙酯萃取得到的石榴皮多酚具有相对最高的抗氧化性能。     

全叶青兰提取物抗氧化活性的研究

以全叶青兰经超临界CO2萃取后的萃取物为原料,采用乙醇提取后,根据极性差异经乙醚、乙酸乙酯和正丁醇依次萃取,对所得提取物的抗氧化活性进行了研究。结果表明,3种提取物对DPPH自由基和羟基自由基均具有比较强的抗氧化活性。其清除DPPH自由基的能力比较接近,而对羟基自由基的清除能力三者差异较大。其中,乙酸乙酯和乙醚提取物清除羟基自由基的半数清除率要明显小于同等条件下的对照品芦丁和BHT的清除浓度,正丁醇提取物清除DPPH自由基的半数清除率的浓度明显要小于清除羟基自由基的浓度,乙酸乙酯萃取物和乙醚萃取物在两个体系内的差异较小。     

核桃内生真菌LTS-6-6代谢产物的体外抗氧化活性及对油脂氧化稳定性的影响

以核桃内生真菌LTS-6-6为研究对象,通过ABTS自由基清除法、羟基自由基清除法及Fe3+还原能力测定等明确其代谢产物不同极性萃取物的体外抗氧化活性;采用Schaal烘箱法,以油脂过氧化值、酸值作为指标,测定添加高活性萃取物对菜(籽)油氧化稳定性的影响.研究结果表明,4种萃取物中,乙酸乙酯萃取物(Ethyl acet...     

不同极性柳叶蜡梅叶萃取物总酚含量及其抗氧化、抑菌能力研究

采用甲醇回流提取、梯度萃取得到正己烷萃取物、二氯甲烷萃取物、乙酸乙酯萃取物、正丁醇萃取物和水萃取物5个不同极性部分,以多酚含量、还原能力、对1,1-二苯基-2-三硝基苯肼(DPPH)自由基的清除能力及抑制微生物生长为评价指标,研究其体外抗氧化和抑菌活性能力。结果表明:柳叶腊梅叶多酚量较为丰富,乙酸乙酯萃取物含量最多,为(309.5±4.81)mg/g。柳叶腊梅叶萃取物具有较强的抗氧化活性,其还原能力和对DPPH自由基清除能力随其浓度的增加而增强。甲醇、正己烷、二氯甲烷、乙酸乙酯、正丁醇和水萃取物对DPPH自由基清除能力的半数抑制浓度(IC50)值分别为1.24,1.11,0.61,0.48,0.98,1.36 mg/mL。柳叶腊梅叶萃取物对大肠杆菌、金黄葡萄球菌、枯草芽孢杆菌和绿脓杆菌均有抑制作用,二氯甲烷萃取物的抑菌活性最显著,其对4种受试菌的最低抑制浓度为2 mg/mL。故柳叶腊梅叶萃取物具有较好的抗氧化和抑菌特性,为进一步分离提取活性化合物提供依据。     

DHA油脂在精炼过程中氧化稳定性的变化

分析了DHA毛油依次经历脱胶、碱炼、脱色、脱臭等环节后,油脂的微组成及氧化稳定性变化.结果显示,在整个精炼过程中各微组分的含量整体呈下降趋势. DHA油脂对光稳定性:精油＞脱色油＞毛油/脱胶＞碱炼油;DHA油脂对热稳定性(Rancimat法):脱色油＞精油＞脱胶油＞毛油＞碱炼油.DHA油脂在脱色环节之前,氧化稳定性差归因于其中促进氧化的微组分过多.在脱色环节之后油脂对热稳定性变差,归因于内源性的抗氧化组分在脱臭环节中大量损失.     

芝麻林素的酸催化反应与抗氧化性分析

采用石油醚、甲醇和乙醇溶解芝麻林素,研究不同溶剂体系芝麻林素酸催化反应的现象;以1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力评价芝麻林素及其分解产物的抗氧化能力;采用磷钨杂多酸（phosphotungstic heteropoly acid,HPW）催化芝麻油中芝麻林素的转化,研究芝麻林素酸催化对冷榨芝麻油氧化稳定性的影响。结果表明：芝麻林素在3 种溶剂体系中酸催化反应的产物不尽相同,芝麻酚是共同产物,石油醚体系产生Semin和芝麻素酚,甲醇和乙醇体系均出现不同未知物;芝麻林素和芝麻素的DPPH自由基清除能力远低于特丁基对苯二酚、丁基羟基茴香醚、丁基羟基甲苯和芝麻酚,但石油醚体系芝麻林素酸催化产物的DPPH自由基清除能力大幅提高,为HPW催化芝麻林素提高冷榨芝麻油氧化稳定性提供了理论依据;随着HPW催化剂添加量的增加,冷榨芝麻油中的芝麻林素含量逐渐减少,芝麻酚和芝麻素酚的含量逐渐升高,同时冷榨芝麻油的氧化诱导时间逐渐延长,氧化稳定性增强。     

Oregano and rosemary extracts inhibit oxidation of long-chain n-3 fatty acids in menhaden oil

ABSTRACT:  Capabilities of methanol extracts from oregano and rosemary in retarding oxidation of long-chain polyunsaturated fatty acids, docosahexaenoic acid C22:6 (DHA) and eicosapentaenoic acid C20:5 (EPA), in menhaden oil were investigated. The fish oils after mixing with the extracts at different concentrations were oxidized in an accelerated study by heating at 150 °C for 30 min or incubating at 60 °C for 5 d. After heating at 150 °C, only 15.9% of DHA and 18.5% of EPA remained in the fish oil without extract, while 38.8% to 65.9% of DHA and 44.7% to 69.0% of EPA were retained in the fish oil mixed with 1% to 5% of oregano extract. The highest retained DHA (56.9%) and EPA (58.0%) in the fish oils mixed with rosemary extract were observed at 2.5% addition. Increasing rosemary extract to 5% lowered its capability of inhibiting DHA and EPA oxidation. After incubation at 60 °C for 5 d, the highest inhibition capability was also found at 2.5% of added rosemary extract, and the oil retained 88.2% DHA and 88.3% EPA. However, only 18.8% DHA and 23.6% EPA were retained in the fish oil mixed with 5% of oregano extract and no DHA and EPA were detected in the fish oil without extract after 5-d incubation at 60 °C. Thus, antioxidant activity of the rosemary extract was greater than that of oregano extract, but was sensitive to heat. The rosemary extract also demonstrated higher DPPH (2,2'-diphenyl-1-picrylhydrazyl) free radical scavenging capability, which was approximately 3 times higher than oregano extract, although there was no significant difference in the total phenolic contents between both extracts.     

ANTIOXIDANT PROPERTIES OF MOLDAVIAN DRAGONHEAD (DRACOCEPHALUM MOLDAVICA L.)

The antioxidant power of acetone oleoresin (AO), deodorized acetone extract (DAE) and methanol extract (ME) isolated from Moldavian dragonhead ( Dracocephalum moldavica L.) leaves and flowering parts was tested in stripped corn oil and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging system. The activity of ME or rosmarinic acid mixtures with α-tocopherol was also determined in corn oil. The results showed that methanol was a considerably more effective solvent to extract antioxidative substances from dragonhead than acetone. Dragonhead ME was efficient both in retarding corn oil peroxidation and in scavenging DPPH free radicals. The effectiveness of dragonhead AO isolated from the whole herb and DAE isolated from deodorized herb was significantly lower. Their activities were similar in DPPH radical scavenging, whereas DAE was more efficient in stripped corn oil than AO. Dragonhead ME was fractionated by thin     

菜籽油低共熔溶剂萃取物抗氧化活性研究

以菜籽油为材料,DPPH自由基清除活性为指标,比较了氯化胆碱-尿素、氯化胆碱-甘油、氯化胆碱-乙酰丙酸3种低共熔溶剂(DES)和80%甲醇萃取物的抗氧化活性,筛选出最优的低共熔萃取剂,并分析了其与80%甲醇萃取物的抗氧化成分差异。研究表明：氯化胆碱-乙酰丙酸低共熔溶剂菜籽油萃取物的抗氧化活性显著高于80%甲醇萃取物,而氯化胆碱-尿素和氯化胆碱-甘油低共熔溶剂萃取物的抗氧化活性低于80%甲醇。通过总酚含量测定、薄层层析-DPPH显色、HPLC等方法,比较了氯化胆碱-乙酰丙酸低共熔溶剂和80%甲醇萃取物成分的差别,氯化胆碱-乙酰丙酸低共熔溶剂萃取物的总酚含量是80%甲醇的143.27%,抗氧化物质的种类和数量也比80%甲醇萃取物有显著的提升。因此氯化胆碱-乙酰丙酸低共熔溶剂可用于植物油脂抗氧化成分萃取和分析。     

DHA油脂在精炼过程中氧化稳定性的变化

分析了DHA毛油依次经历脱胶、碱炼、脱色、脱臭等环节后,油脂的微组成及氧化稳定性变化。结果显示,在整个精炼过程中各微组分的含量整体呈下降趋势。DHA油脂对光稳定性:精油>脱色油>毛油/脱胶>碱炼油;DHA油脂对热稳定性(Rancimat法):脱色油>精油>脱胶油>毛油>碱炼油。DHA油脂在脱色环节之前,氧化稳定性差归因于其中促进氧化的微组分过多。在脱色环节之后油脂对热稳定性变差,归因于内源性的抗氧化组分在脱臭环节中大量损失。      

Antioxidation activity of oil extracts prepared from various seeds

The anti-oxidative activity of ethanol and methanol extracts from various seed oils (perilla seed oil, camellia seed oil, pine seed oil, flaxseed oil, and olive oil) was investigated using DPPH free radical scavenging activity (DPPH-RSA), hydroxyl radical scavenging activity (Hydroxyl-RSA), fluorescent development, browning level development, microsomal lipid peroxidation (MLP), and t-BOOH-induced cytotoxicity assays. Both browning and fluorescence level were observed higher value in methanol extract of camellia seed oil (CSO-ME). This meant that CSO-ME had more available antioxidant matters. Radical scavenging activity of CSO-ME was the highest among all seed oil extracts, and was 61.1% in the DPPH-RSA and 64.5% in the Hydroxyl-RSA test. Based on in vitro tests, all extract treatments significantly reduced both thiobarbituric acid-reactive substrate formation and lactate dehydrogenase release, indicating high antioxidant activity. These results suggest that ethanol and methanol extracts from seed oils can be a potentially good dietary lipid supplement source against oxidative stress.     

Antioxidant properties of methanolic extracts from different parts of Sclerocarya birrea

The methanolic extracts from Sclerocarya birrea leaves (SCL), roots (SCR), barks (SCB), and kernel oil cake (SCK) were examined for radical scavenging capacities and antioxidant activities. The total phenolics of the extracts was determined spectrophotometrically according to the Folin‐Ciocalteau method using gallic acid as standard solution. The total phenolic compounds were found as 304.5, 367.5, 593, 148.0 and 258.0 mg g^‐1 of dry product, respectively. The extracts of SCL, SCR, SCB and SCK were markedly effective in inhibiting the oxidation of linoleic acid and subsequent bleaching of β‐carotene in comparison with the control. Based on oxidation of β‐carotene/linoleic acid, the SCK extract is the most effective followed by SCR, SCL and SCB extract. The antioxidant activity determined by the DPPH (1,1‐diphenyl‐β‐picrylhydrazyl) method revealed that the SCK extract had the highest antioxidant activity on DPPH free radicals followed by SCB, SCR and SCL extracts. The effect of different extracts on the oxidative stability of sunflower oil at 70 °C was tested in the dark and compared with BHA. The oil peroxide values (PVs) were generally lower with the addition of extract in comparison to a control.     

天然抗氧化剂对辣椒鸡油抗氧化性能的影响

为了筛选出适合辣椒鸡油的天然抗氧化剂,以延长其保质期,研究并比较了6种天然抗氧化剂（迷迭香提取物、维生素E、茶多酚、维生素C、槲皮素和硫辛酸）对辣椒鸡油酸值、过氧化值、DPPH自由基清除能力和总还原能力的影响。结果表明：6种天然抗氧化剂在辣椒鸡油中均具有一定的抗氧化能力;在抑制酸值方面,槲皮素效果最佳,维生素C最差;在抑制过氧化值方面,槲皮素效果最佳,维生素E最差;在DPPH自由基清除能力方面,迷迭香提取物效果最佳,硫辛酸最差;在总还原能力方面,槲皮素效果最佳,维生素E最差;槲皮素、迷迭香提取物和茶多酚在酸值、过氧化值、DPPH自由基清除能力和总还原能力方面均位于前三。综合考虑抗氧化效果、抗氧化剂稳定性、成本等因素,可优先选择迷迭香提取物和茶多酚作为辣椒鸡油的抗氧化剂以提高其储藏性能。     

Fatty acid profile, thymoquinone content, oxidative stability, and antioxidant properties of cold-pressed black cumin seed oils

Six different batches of cold-pressed black cumin seed oils (BCSO) were evaluated for their fatty acid profiles, thymoquinone contents, oxidative stability, and antioxidant properties. Linoleic, oleic, and palmitic acids were the major fatty acids in the tested oils. The cold-pressed BCSO samples differed in their oxidative stability measured as the oxidative stability index (OSI). The greatest OSI was about 155 h, and the lowest OSI was proximately 76 h, reflecting a 2-fold difference in their oxidative stability. These BCSO contained significant level of phenolic components with a concentration ranging from 1.02 to 1.40 mg gallic acid equivalents/g oil. In addition, BCSO contained about 3.48-8.73 mg/g thymoquinone and trace amount of dithymoquinone. Electron spin resonance (ESR) analysis showed that cold-pressed BCSO contained natural antioxidants and was able to suppress radical mediated lipid peroxidation in fish oil. The methanol extracts of BCSO could directly react with and quench DPPH radicals, which further confirmed the antioxidant property of these BCSO. The results from the present study suggest that cold-pressed black cumin seed oil may serve as an excellent dietary source of thymoquinone and natural antioxidants.     

秦岭山脉野生蒲公英提取物的抗氧化活性及其对胡麻油氧化稳定性的影响

以秦岭山脉野生蒲公英全草为原料,采用超声波纤维素酶同步法提取总活性成分。对蒲公英提取物的DPPH自由基清除能力、超氧阴离子自由基清除能力、羟自由基清除能力和总还原能力进行了测定,并与人工合成VC进行了比较,同时采用加速氧化的方法评价蒲公英提取物对胡麻油氧化稳定性的影响,并与BHT、迷迭香提取物进行比较。结果表明:蒲公英提取物比人工合成VC有更高的抗氧化活性; 3种抗氧化剂抗氧化能力大小为迷迭香提取物(700 mg/kg)>蒲公英提取物(700 mg/kg)> BHT(200 mg/kg),并且蒲公英提取物添加量与胡麻油的氧化稳定性呈正相关。因此,秦岭山脉野生蒲公英全草总活性成分提取物可作为天然抗氧化剂用于延缓食用油氧化。