含硒银杏叶清除羟基自由在的ESR研究

利用电子自旋共振技术（ＥＳＲ）研究了含硒银杏叶提取物对Ｈ２Ｏ２－Ｆｅ＾２＋体系产生的羟基自由基的清除作用。与ＳＯＤ、茶多酚相比,含硒银杏叶提取物对羟基自基也有很强的清除效果,增添了有实用价值的天然、无公害的清除羟基自由基的新资源。     

用ESR技术研究含硒蛋白抗羟基自由基作用的活性

用ＥＳＲ技术研究含硒蛋白抗羟基自由基作用的活性。与ＳＯＤ、茶多酚相比较,含硒蛋白对羟基自由基的清除也有显著作用。找到了一种有实用价值,天然无毒,抗羟基自由基的新资源。     

灰树花提取物清除氧自由基的研究

采用化学发光法比较了灰树花各提取物对超氧阴离子自由基、羟基自由基的清除效果。研究结果表明,灰树花子实体和菌丝体的提取物对羟基自由基均有很好的清除作用,灰树花菌丝体水提物(GFME)、灰树花子实体水提物(GFE)、灰树花子实体水提多糖(GFP)、灰树花子实体碱提多糖(GFAP)清除羟基自由基的IC50均小于1.0 mg/mL,其他提取物清除羟基自由基的IC50也均小于3.0 mg/mL。而对超氧阴离子自由基仅GFME、GFMP、GFE有清除作用,其他的提取物清除作用很弱。     

九种药用植物花黄酮类物质提取及对羟自由基清除能力的研究

微波辅助法提取九种药用植物花中黄酮类化合物,研究其提取物清除羟基自由基(·OH)的能力.九种药用植物花提取物对羟基自由基有不同程度的清除作用,且生态环境对该作用有较大影响,其中旋覆花中总黄酮含量最高,夏至草花总黄酮含量最低;荷兰菊、旋覆花、玫瑰花清除羟基自由基能力较强,清除率在一定浓度范围内与提取物浓度呈正相关.     

印度块菌提取物抗氧化活性的研究

对印度块菌Tuber indicum子实体的提取物,包括55%乙醇粗提物(ECE)、石油醚提取物(PEF)和乙酸乙酯提取物(EAF)的清除DPPH自由基和羟基自由基能力、铁离子鳌合能力以及各提取物的总酚含量等进行了研究和测定,结果显示,3种提取物的清除自由基能力和铁离子鳌合能力具有显著差异(P0.05);ECE对DPPH自由基的清除活性最高,其EC50值为1.61g/L;EAF对羟基自由基及铁离子表现出较强的清除或螯合的能力,其EC50值分别为3.31g/L和0.70g/L;EAF的总酚含量(2.964mg GAE/g提取物)最高,其次是ECE,总酚含量为(2.618mg GAE/g提取物);PEF的清除自由基和铁离子鳌合能力较差,其总酚含量也最低(1.124mg GAE/g提取物);总酚含量与印度块菌提取物清除自由基以及鳌合铁离子的能力密切相关。     

李氏块菌提取物抗氧化活性的研究

对李氏块菌Tuber liyuanum子实体的不同提取物,包括甲醇提取物(ME)、乙醇提取物(EE)、丙酮提取物(AE)、正丁醇提取物(BAE)和乙酸乙酯提取物(EAE),进行清除DPPH自由基、羟基自由基、超氧阴离子自由基、铁离子螯合能力、还原力以及总酚含量的测定和研究,发现ME对DPPH自由基、超氧阴离子自由基清除及还原力活性最高,EC50值分别为23.37mg/m L、11.65mg/m L和24.47mg/m L;EE对羟基自由基清除和铁离子螯合能力活性最高,EC50值分别为7.24mg/m L和小于0.5mg/m L;ME的总酚含量最高(3.08mg GAE/g提取物),其次是EE(1.34mg GAE/g提取物),提取物总酚含量与抗氧化活性呈现出一定的正相关性。     

沱茶中抗自由基化学成分的研究

对沱茶(Camellia sinensis var．assamica)的水提取物、50％甲醇提取物、甲醇提取物进行了DPPH自由基清除作用的研究,实验结果表明,水提取物和50％甲醇提取物均具有较强的清除自由基作用,其半数抑制率(IC50)分别为6．07μg／mL和5．01μg／mL,而甲醇提取物清除自由基作用的活性则较弱,其半数抑制率(IC50)为39．63μg/mL。利用层析等手段分别从抗自由基活性较强的水提取物的甲醇可溶部分分离获得了20种化合物,其中,10种化合物(2、5、6、11、12、13、16、17、18、19)为首次从该植物中得到的化合物;DPPH自由基清除活性研究结果表明,其中化合物(1、4、7、9、10、12、14、18)的活性强于阳性对照品抗坏血酸和咖啡酸。比较分析化合物的结构与其活性的关系,发现结构中苯环上有邻位羟基的化合物其清除自由基的活性较强,而且羟基越多活性越强。     

樟芝发酵液和菌丝体提取物抗氧化性能研究

采用甲醇、乙醇、异丙醇对樟芝发酵液和菌丝体进行提取,对其不同提取物进行还原力,DPPH、羟基自由基、超氧自由基、过氧化氢清除能力,亚铁离子螯合能力等抗氧化能力的测定。比较发酵液提取物和菌丝体提取物的抗氧化效果,比较不同提取剂提取物的抗氧化效果。结果显示:(1)发酵液提取物还原力最高的为异丙醇提取物,亚铁离子螯合能力最强的为乙醇提取物;DPPH清除能力乙醇和异丙醇提取物最高都达到97.88%;羟基自由基清除能力最高的为乙醇提取物,达到84.22%;3种提取物的超氧自由基清除能力都较高,具有最高清除率的异丙醇提取物达到94.89%;过氧化氢清除能力最高的为乙醇提取物的97.53%。(2)菌丝体提取物还原力最高和亚铁离子螯合能力最强的均为乙醇提取物;DPPH清除能力最高的为乙醇提取物的89.95%;3种提取物的羟基自由基清除能力普遍偏低,最高的仅为异丙醇提取物的37.28%;超氧自由基清除能力则普遍较高,最高为甲醇提取物的90.05%;过氧化氢清除能力最高的为乙醇和异丙醇提取物,最高清除率均为95.06%。抗氧化性能的研究比较,为进一步开发利用樟芝提供了依据。     

暴马丁香叶乙醇提取物的体外抗氧化活性

以乙醇为溶剂,采用超声波辅助提取,得到暴马丁香叶乙醇提取物。气相色谱-质谱(GC-MS)分析结果表明,暴马丁香叶乙醇提取物主要由烷烃类、酯类、醇类、芳香族化合物等组成,GC含量较高的化合物为十一烷(12.38%)、对二甲苯(6.58%)、乙苯(3.72%)、4-O-甲基-d-阿拉伯糖(2.22%)、乙酸丁酯(0.55%)、柏木醇(0.07%)等。暴马丁香叶乙醇提取物的抗氧化活性实验结果表明,清除50%DPPH自由基的暴马丁香叶乙醇提取物浓度(IC_(50))值为0.014 mg/mL,清除50%羟基自由基的暴马丁香叶乙醇提取物浓度(IC_(50))值为4.171 mg/mL。暴马丁香叶乙醇提取物对羟基自由基的清除效果优于抗坏血酸。     

水淹对杨树木材提取物清除DPPH有机自由基活性影响初探

以生长在长江滩地三种类型(江滩、洲滩、湖滩)上、三种水淹状况下2个品系的人工林杨树木材(欧美杨无性系72杨、美洲黑杨无性系69杨)木材为研究对象,用二苯基苦基苯肼自由基(DPPH)酶标仪法,对其80%甲醇提取物的自由基清除活性进行了比较,发现相同立地上杨树边材和心材提取物的自由基清除活性存在显著差异;且边材提取物的自由基清除活性普遍较高.不同立地上杨树心材提取物的自由基清除活性差异不显著;但边材提取物的自由基清除活性存在较大的差异,其中水淹深度为1 m和3 m的杨树边材提取物自由基清除活性差异达到极显著水平.相关性分析表明,心材提取物的IC50与水淹深度呈显著的负相关,边材提取物的IC50与水淹深度呈极显著的正相关.     

枇杷花茶水提物的镇咳、抗炎与抗氧化作用研究

采用小鼠氨水致咳法研究枇杷花茶水提物镇咳效果,以二甲苯致小鼠耳肿胀法研究其抗炎效果,并从枇杷花茶的还原能力及对超氧阴离子和羟自由基的清除作用分析枇杷花茶水提物的抗氧化效果。结果表明,枇杷花茶的水提物高剂量组(3000 mg·kg-1)、低剂量组(700 mg·kg-1)均有镇咳抗炎效果,水提物的浓度越高,效果越好。各浓度枇杷花茶水提物均表现出一定的还原能力,对于羟基自由基和超氧阴离子都有一定的清除效果。其中,20 mg·mL-1水提物还原效果最好(吸光值0.903),超过0.2 mg·mL-1抗坏血酸(吸光值0.814);10 mg·mL-1的水提物对超氧阴离子的清除率为47.32%;20 mg·mL-1水提物对于羟基自由基的清除效果非常明显,清除率为91.62%。枇杷花茶水提物镇咳、抗炎、抗氧化效果明显。     

Antioxidant activity of extract from Polygonum cuspidatum

Numerous diseases are induced by free radicals via lipid peroxidation, protein peroxidation and DNA damage. It has been known that a variety of plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum cuspidatum Sieb. et Zuce has antioxidant activity is unknown. In this study, dried roots of Polygonum cuspidatum were extracted by ethanol and the extract was lyophilized. Free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays were employed to study antioxidant activities. The results indicate that the IC50 value oí Polygonum cuspidatum extract is 110 microg/ml in free radical scavenging assays, 3.2 microg/ml in superoxide radical scavenging assays, and 8 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum cuspidatum extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 641.1 +/- 42.6 mg/g and 62.3 +/- 6.0 mg/g. The results indicate that Polygonum cuspidatum extract clearly has antioxidant effects.     

In vitro antioxidant activity of Diospyros malabarica Kostel bark

Antioxidant activity of defatted methanol extract of D. malabarica bark was studied for its free radical scavenging property on different in vitro models e.g. 1,1-diphenyl-2-picryl hydrazyl (DPPH), nitric oxide, superoxide, hydroxyl radical and lipid peroxide radical model. The extract showed good dose-dependent free radical scavenging property in all the models except in hydroxyl radical inhibition assay. IC50 values were found to be 9.16, 13.21, 25.27 and 17.33 microg/ml respectively in DPPH, nitric oxide, superoxide and lipid peroxidation inhibition assays. In hydroxyl radical inhibition assay 1000 microg/ml extract showed only 10% inhibition with respect to the control. Measurement of total phenolic compounds by Folin-Ciocalteu's phenol reagent indicated that 1 mg of the extract contained 120.7 microg equivalent of pyrocatechol. The results indicate that the antioxidant property of the extract may be due to the high content of phenolic compounds. However, the underlying mechanism may not involve hydroxyl radical scavenging property.     

Antioxidant activity of extract from Polygonum aviculare L

Free radicals induce numerous diseases by lipid peroxidation, protein peroxidation, and DNA damage. It has been reported that numerous plant extracts have antioxidant activities to scavenge free radicals. Whether Polygonum aviculare L. (Polygonaceae) has antioxidant activity is unknown. In this study, dried Polygonum aviculare L. was extracted by ethanol, and the extract was lyophilized. The antioxidant activities of extract powder were examined by free radical scavenging assays, superoxide radical scavenging assays, lipid peroxidation assays and hydroxyl radical-induced DNA strand scission assays. The results show that the IC50 value of Polygonum aviculare L. extract is 50 microg/ml in free radical scavenging assays, 0.8 microg/ml in superoxide radical scavenging assays, and 15 microg/ml in lipid peroxidation assays, respectively. Furthermore, Polygonum aviculare L. extract has DNA protective effect in hydroxyl radical-induced DNA strand scission assays. The total phenolics and flavonoid content of extract is 677.4 +/- 62.7 microg/g and 112.7 +/- 13 microg/g. The results indicate that Polygonum aviculare L. extract clearly has antioxidant effects.     

Evaluation of antioxidant activity of <Emphasis Type="Italic">Melothria maderaspatana in vitro</Emphasis>

In this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant.     

罗汉果不同溶剂提取物抗氧化及清除活性氧自由基作用

以水、甲醇、乙醇和乙酸乙酯为溶剂,对罗汉果干果进行提取,分别采用磷钼酸铵体系、邻苯三酚自氧化体系、Fenton反应体系和卵黄脂质过氧化体系测定各种提取物的总抗氧化性能、超氧阴离子自由基和羟基自由基清除性能及其抗脂质过氧化作用。结果表明,四种溶剂提取物均具较强的抗氧化性和活性氧自由基清除性能,其能力的大小顺序为:乙酸乙酯提取物>水提物>甲醇提取物>乙醇提取物。     

Antioxidant activity and protective effect on DNA strand scission of Rooibos tea (Aspalathus linearis)

Rooibos tea (Aspalathus linearis) was extracted by refluxing with water and 75% ethanol as a solvent. Antioxidant activity and protective effect on DNA strand scission were investigated by using different antioxidant assay systems and DNA strand nicking assay, respectively. 75% Ethanol extract has higher content of total soluble phenolics and flavonoid than water extract. Antioxidant activities such as hydrogen donating capacity and scavenging activity of hydrogen peroxide were higher in 75% ethanol extract than in water extract except the rate constant with hydroxyl radical. Peroxyl radical induced DNA strand scission was prevented by both 75% ethanol and water extract and hydroxyl radical induced DNA strand scission was not. This result indicates that total soluble phenolics, specially flavonoid, of Rooibos tea are responsible for several kinds of antioxidant activities and preventive activity on peroxyl radical induced DNA strand scission.     

Superoxide anion and hydroxyl radical scavenging activities of vegetable extracts measured using electron spin resonance.

Radical scavenging by reconstituted lyophilized powders of water extracts from 16 common vegetables was measured using electron spin resonance (ESR) with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), hydroxyl radicals, (.OH) or superoxide anion radicals (O2.-), as DMPO-OH or DMPO-OOH spin adducts. On a dry weight basis, eggplant, and red, yellow and green bell pepper extracts showed potent superoxide anion radical scavenging activities (SOD-like activities). Ascorbate oxidase- or heat-treatments, decreased SOD-like activities in bell pepper extracts suggesting that ascorbate accounts for much of their free radical scavenging activity. Eggplant epidermis extract exhibited the most potent hydroxyl radical scavenging and SOD-like activities. Eggplant SOD-like activity did not decrease after ascorbate oxidase treatment, but decreased following ultrafiltration demonstrating that SOD-like activity is partially due to high molecular weight substances. Nasunin, an anthocyanin in eggplant epidermis, showed markedly potent superoxide anion radical scavenging activity, while it inhibited hydroxyl radical generation probably by chelating ferrous ion.