亚热带部分常见芳香油树种鲜叶提取物清除自由基的活性研究

用二苯基苦基苯脱自由基(DPPH)酶标仪法，对亚热带常见的80余种芳香油树种鲜叶80％甲醇提取物的自由基清除活性进行了比较，发现所有树种提取物的自由基清除率都随质量浓度的增加和随着37℃下孵育时间的延长而增大。其中，黄连木、枫香、杨梅、木香花、小果蔷菇等树鲜叶的提取物有很强的自由基清除活性，它们在相当于鲜叶质量浓度为0．5mg／mL、37℃下孵育20min时的自由基清除率分别达90．6％、85．7％、79．1％、62．5％和61．3％。同时，紫楠、湿地松、大果山胡椒、红果山胡椒、月季、刺柏、豹皮樟等也有较强的清除自由基活性，它们在质量浓度为0．5mg／mL时的自由基清除率都在50％以上。这些树种均有较大的开发潜力。     

松树皮多聚原花青素片段化产物的分离鉴定及活性

采用多种柱层析手段,分别从基于茶多酚的思茅松和马尾松树皮多聚原花青素片段化反应产物中分离得到1个主要产物。通过MS、1H NMR和13C NMR波谱解析,其化学结构鉴定为(-)-表儿茶素-(4β-8)-(-)-表没食子儿茶素3-O-没食子酸酯(1)。结果表明,茶多酚中的(-)-表没食子儿茶素3-O-没食子酸酯(EGCG)在片段化反应中扮演着重要角色,化合物1是EGCG通过4β-8与(-)-表儿茶素C-4位上的正离子键合形成而来。采用DPPH、ABTS自由基清除活性测定方法评价了化合物1的抗氧化活性,其清除DPPH、ABTS自由基的能力均高于茶多酚、多聚原花青素及其片段化总产物,SC50值分别为6.12±0.03 g/m L和41.41±0.66 g/m L。     

金花茶组植物花朵内多酚组分含量分析

[目的 ]研究金花茶组植物花朵及不同花器官中多酚组分的组成和含量,为多酚组分在金花茶植物分类中的应用提供参考。[方法 ]利用HPLC方法测定金花茶组22种植物全开期花朵的花瓣、雄蕊、萼片3类器官中9种多酚组分含量,并利用聚类分析方法解析其与金花茶组植物分类的关系。[结果 ]在所测的9种多酚组分中,GCG、ECG、CG在全部样品中均检测到,而GA、GC、EGC、C、EC、EGCG在不等数量的样品中未被检测到。多酚含量最高的组分为EC,其次是EGC、GCG和ECG,剩余5种组分含量很低,前4种组分是花朵多酚总量的主要成分。在3类器官中,多酚总量及EGC、C、EC、EGCG、GCG、ECG 6种组分含量的排序为:萼片雄蕊花瓣;CG组分含量的排序为:花瓣雄蕊萼片;GA和GC组分含量的排序为:雄蕊萼片花瓣。聚类分析发现,雄蕊多酚组分聚类结果与各分类系统的相似率最高,达80.00%～90.00%,萼片多酚分类结果相似率为75.00%～88.89%,花瓣多酚分类结果相似率为58.33%～81.82%。[结论 ]金花茶花朵中多酚组分含量最高的为EC,主要多酚组分为EC、EGC、GCG和ECG,在3类器官中多酚含量的排序为:萼片雄蕊花瓣。雄蕊多酚组分的聚类结果可以作为金花茶组植物系统分类的有效补充。     

油茶叶乙醇提取物清除DPPH自由基作用的研究

用二苯基苦基肼自由基(DPPH·)法测定了油茶叶乙醇提取物的抗氧化活性,并与芦丁、二丁基羟基甲苯(BHT)进行了比较,在波长517 nm、反应时间40 min的条件下测定了DPPH·的清除率为50%时抗氧化剂的质量浓度(EC50)值.结果表明,油茶叶乙醇提取物时DPPH·具有明显的清除作用,且随着油茶叶乙醇提取物纯化程度的提高,其清除能力也相应增强.测得油茶叶粗提物、油茶叶精提物、芦丁和BHT清除DPPH·的EC50值分别为12.19、6.765、9.481和37.53 mg/L,清除DPPH·能力的大小顺序依次为油茶叶精提物＞芦丁＞油茶叶粗提物＞BHT.     

山楂叶总黄酮清除DPPH和超氧阴离子自由基的活性研究

以山楂秋日落叶为原料,70%乙醇为溶剂,提取得到山楂叶总黄酮。以芦丁和VC为对照,采用分光光度法研究了山楂叶总黄酮对DPPH自由基和超氧阴离子自由基的体外清除活性。结果表明,山楂叶总黄酮对DPPH自由基和超氧阴离子自由基均具有一定的清除作用。对DPPH自由基的清除率随加入量的增加而增加,当加入量为2 mg时,清除率为50.29%;而对超氧阴离子自由基的清除在加入量为1.2 mg时达到最高值27.36%。芦丁对二自由基的最高清除率分别为63.83%和32.55%;而VC则分别为69.93%和99.04%。经比较发现,山楂叶总黄酮的清除自由基活性稍低于芦丁,远低于VC。     

迎春叶黄酮的提取纯化及清除自由基活性研究

研究迎春叶总黄酮(FLJN)的提取、分离、纯化条件及其体外清除自由基的能力.正交试验结果显示最佳提取方法为:采用75%的乙醇水溶液为提取液,1: 15(g: mL)的固液比,水浴回流热提取3次,每次40min.粗提物经过活性炭吸附法进一步处理后,可得总黄酮质量分数为97.6%的精制产品.体外实验表明,FLJN可以有效地清除二苯基苦基苯肼自由基(DPPH · )和羟自由基( · OH),自由基清除率为50%时溶液的质量浓度(IC_(50)值)分别为8.40和2.24mg/L,其清除自由基的能力与芦丁基本相当,比2,6 - 二叔丁基 - 4 - 甲基苯酚(BHT)稍弱.     

黄藤笋和4种常见茎菜抗氧化活性的比较研究(英文)

以纯水和100%乙醇作为提取溶剂,采用超声波和50℃水浴萃取法获得了黄藤笋和4种常见茎类蔬菜(芦笋、茭白、莴笋和甜麻竹)的提取液,并通过DPPH法测定了这些提取液的总抗氧化活性(DPPH自由基清除率)。结果表明:黄藤笋提取液的抗氧化活性最强,其次是芦笋,甜麻竹提取液的抗氧化活性最低。黄藤笋、芦笋和莴笋乙醇提取液的抗氧化活性高于水提取液的抗氧化活性,而茭白和甜麻竹则相反。除甜麻竹外,其余4种茎菜提取液的抗氧化活性不因萃取方法的不同而有显著差异。研究还表明,黄藤笋提取液在稀释到3200倍时,DPPH自由基清除率仍有0.33%,而其他4种常见茎菜在稀释2～10倍后已丧失自由基清除能力。研究表明,黄藤笋作为保健品的添加剂具有很高的潜在利用价值。     

50种木材提取物清除自由基活性初探

用二苯基苦基苯肼自由基(DPPH·)酶标仪法,对亚热带常见的50种木材甲醇提取物的自由基清除活性进行了比较,发现不同木材提取物的自由基清除活性差别很大,最大相差15.48倍,其中刺槐、桑树、李树、桃树和杉木的木材提取物具有较强的清除自由基活性,它们单位质量干样的半数清除质量浓度(IC50)分别为:0.52、0.64、0...     

木麻黄树皮提取物的清除羟自由基活性

考察了4种木麻黄树皮水提取物的化学组成及其对绝对分子质量分布的影响因素,用邻二氮菲-Fe2+氧化法测定了不同树种和不同溶剂提取物对羟自由基的清除率.结果表明,不同提取溶剂对木麻黄树皮提取物组成、绝对分子质量分布影响较大.盐酸-丙酮-水溶液(HAW,1.0%盐酸与丙酮溶液质量比7∶3)作提取溶剂可大幅提高提取物的总固形物和多酚含量.应用激光散射-凝胶渗透色谱(SEC)技术测得山地木麻黄树皮HAW提取物的绝对分子质量为5×102～2×105.木麻黄提取物清除羟自由基的活性高,质量浓度为2g/L的山地木麻黄树皮HAW提取物对羟自由基的清除率高达81.6%.提取物的组成影响其清除羟自由基活性.     

东紫苏挥发油的化学组成及其抗氧化活性研究

通过蒸馏对东紫苏挥发油进行提取，利用气相色谱-质谱联用技术(GC-MS)分析其化学成分，并采用DPPH自由基清除法对其抗氧化活性进行测定。结果显示：东紫苏挥发油中检测出16种化合物，占总挥发油质量的80.32%,其中桉树醇的相对质量分数最高，占43.57%。东紫苏挥发油在1.83～8.29 mg/mL浓度范围内，与DPPH自由基清除率呈现出良好的量效关系，IC50值为12.25 mg/mL,表明东紫苏挥发油具有良好的抗氧化活性。     

密蒙花总黄酮清除自由基活性研究

为了解密蒙花总黄酮清除自由基的能力,利用紫外-可见分光光度法对比研究了密蒙花总黄酮对1,1-二苯基-2-苦基肼自由基(DPPH.)、羟基自由基(.OH)、2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基(ABTS+.)和超氧阴离子自由基(O2-.)的清除作用。结果表明,密蒙花总黄酮能有效清除DPPH.、.OH、ABTS+.和O2-.。当密蒙花总黄酮质量浓度达到4.8 mg/L时,对DPPH.、.OH、ABTS+.和O2-.清除率分别可达77.88%、35.42%、85.08%和56.91%。     

Preparation of A-type proanthocyanidin dimers from peanut skins and persimmon pulp and comparison of the antioxidant activity of A-type and B-type dimers

We have established a simple method for preparing large quantities of A-type dimers from peanut skin and persimmon for further structure–activity relationship study. Peanut skins were defatted with hexane and oligomeric proanthocyanidins were extracted from it with 20% of methanol, and the extract was fractionated with ethyl acetate. Persimmon tannin was extracted from persimmon with methanol acidified with 1% hydrochloric acid, after removing the sugar and small phenols, the high molecular weight persimmon tannin was partially cleaved with 6.25% hydrochloric acid in methanol. The ethyl acetate fraction from peanut skins and persimmon tannin cleaved products was chromatographed on AB-8 macroporous resin followed by Toyopearl HW-50F resin to yield about 378.3 mg of A-type (epi)catechin (EC) dimer from 1 kg dry peanut skins and 34.3 mg of A-type (epi)catechin-3-O-gallate (ECG) dimer and 37.7 mg of A-type (epi)gallocatechin-3-O-gallate (EGCG) dimer from 1 kg fresh persimmon fruit. The antioxidant properties of the A-type and B-type dimers were compared in five different assays, namely, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical, hydroxyl radical, lipid peroxidation in mice liver homogenate and erythrocyte hemolysis in rat blood. Our results showed that both A-type and B-type dimers showed high antioxidant potency in a dose-dependent manner. In general, B-type dimers showed higher radical scavenging potency than A-type ones with the same subunits in aqueous systems. But in tissue or lipid systems, A-type dimers showed similar or even higher antioxidant potency than B-type ones.     

Identification and evaluation of antioxidant activities of bamboo extracts

The antioxidant activity of solvent extracts from two main bamboo species, moso bamboo (Phyllostachys pubescens) and madake bamboo (P bambusoides) in Japan, was first evaluated by scavenging free radical of 1,1-diphenyl-2-picrylhydrazyl (DPPH), the inhibition activity for peroxidation of linoleic acid, and the reduction power. The methanol-extracts of moso bamboo culms and madake bamboo leaves presented stronger antioxidant activity compared with DPPH scavenging activity. Methanol-extract of moso bamboo culms was further fractionated by different solvents and n-butanol soluble fraction exhibited the most significant activity in the DPPH scavenging assay. The fractionation of n-butanol soluble extract was isolated by silica gel column with gradient mixture solvent of chloroform and methanol. The isolated fractions were directed by the antioxidant activity measured by scavenging the stable DPPH free radical. It was observed that most of the eluted fractions showed the antioxidative activity. Fractions acquired from elution with the mixture solvent of chloroform and methanol (10:1-5:1) showed stronger antioxidant activity than the other fractions.     

Reactive oxygen species scavenging activities and inhibition on DNA oxidative damage of dimeric compounds from the oxidation of (−)-epigallocatechin-3-O-gallate

The dimeric catechins dehydrotheasinensin A (2) and theacitrin C (3) were prepared from the oxidation of (−)-epigallocatechin-3-O-gallate (EGCG, 1), and their antioxidant activity was investigated using a chemiluminescence (CL) method in vitro. Both compounds showed significant inhibitory effects on reactive oxygen species (O₂⁻, H₂O₂ and •OH) and DNA oxidative damage, with 2 being more potent than 3 and EGCG itself.     

Extraction, purification and antioxidant activity of polysaccharides from bamboo leaves

Ultrasonic extraction (UE) was employed for the extraction of bamboo leaf polysaccharides (BLP). The influential parameters of UE procedure including extraction time, ultrasonic power and solid/liquid ratio were optimized by orthogonal experiments. DEAE-cellulose col- umn chromatography was applied to purify BLP and then the radical scavenging activity of BLP was also evaluated. Optimal extraction conditions were: extraction time of 15 min, ultrasonic power of 300 W, and solid/liquid ratio of 1:15. Four kinds of polysaccharides were obtained by DEAE-cellulose column chromatography; the maximum superoxide radical scavenging rate (20.4%) of BLP was inferior to that of vitamin C (VC, the control) and the hydroxyl radical scavenging rate (50%) was equivalent to that of VC.     

Development of an isocratic HPLC method for catechin quantification and its application to formulation studies

The aim of this study was to develop a simple, rapid and accurate isocratic HPLC analytical method to qualify and quantify five catechin derivatives, namely (+)-catechin (C), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epicatechin (EC) and (-)-epigallocatechin gallate (EGCG). To validate the analytical method, linearity, repeatability, intermediate precision, sensitivity, selectivity and recovery were investigated. The five catechin derivatives were completely separated by HPLC using a mobile phase containing 0.1% TFA in Milli-Q water (pH 2.0) mixed with methanol at the volume ratio of 75:25 at a flow rate of 0.8ml/min. The method was shown to be linear (r(2)>0.99), repeatable with instrumental precision<2.0 and intra-assay precision<2.5 (%CV, percent coefficient of variation), precise with intra-day variation<1 and inter-day variation<2.5 (%CV, percent coefficient of variation) and sensitive (LOD<1μg/mL and LOQ<3μg/mL) over the calibration range for all five derivatives. Derivatives could be fully recovered in the presence of niosomal formulation (recovery rates>91%). Selectivity of the method was proven by the forced degradation studies, which showed that under acidic, basic, oxidation temperature and photolysis stresses, the parent drug can be separated from the degradation products by means of this analytical method. The described method was successfully applied in the in vitro release studies of catechin-loaded niosomes to manifest its utility in formulation characterization. Obtained results indicated that the drug release from niosomal formulations was a biphasic process and a diffusion mechanism regulated the permeation of catechin niosomes.     

偃松松塔多糖的单糖组成分析及活性研究

偃松松塔经乙醇提取后,渣经热水提取、喷雾干燥、醇沉制备偃松松塔多糖(PPCP),并用苯酚硫酸法检测多糖的含量,气相色谱法测定PPCP的单糖组成。研究结果表明:PPCP是一种杂多糖,主要由阿拉伯糖、甘露糖、葡萄糖和半乳糖组成,具有典型的多糖红外光谱特征,4种单糖物质的量比为2.33∶1.00∶2.20∶1.94。通过测定PPCP清除DPPH·、·ABTS^+的能力以及还原能力评价PPCP抗氧化活性,然后通过体外实验评估其对RAW 264.7巨噬细胞免疫调节活性,结果表明:偃松松塔多糖有较强的自由基清除能力和Fe^3+还原能力,偃松松塔多糖以浓度依赖性方式表现出较强的抗氧化活性,在多糖质量浓度为2.0 g/L时,DPPH·的清除率(79.72%)达到最大,·ABTS^+清除率(39.63%)达到最大,其Fe^3+还原能力也达到最大值(0.78);松塔多糖能够刺激RAW 264.7巨噬细胞产生大量的NO,并没有对细胞增殖产生影响。     

O/W型山苍子精油微乳的制备及其性能研究

通过加水法制备山苍子精油微乳,单因素试验考察了不同的表面活性剂、助表面活性剂、表面活性剂与助表面活性剂的质量比(Km)以及制备温度对山苍子精油微乳形成的影响,再通过正交试验,得到水包油(O/W)型山苍子精油微乳的最佳制备条件为:曲拉通X-100(TritonX-100)为表面活性剂,无水乙醇为助表面活性剂,Km值为1,制备温度为25℃。以最佳制备条件中混合表面活性剂与山苍子精油的质量比为9∶1,含水率为70%制得标样1,微乳的平均粒径、多分散系数(PDI)、电导率和pH值分别为13.43nm、0.125、83mS/m和5.82。对标样1进行性能测试分析,发现其在1000~4000r/min的速率下进行离心时,微乳外观无变化,可证明其离心稳定性较好;在标样1和精油中加入等量的亚甲基蓝水溶液,亚甲基蓝水溶液在标样1中的扩散速度显著快于在精油中的,可证明微乳的水溶性显著优于精油;在缓释12h后,微乳中缓释的柠檬醛含量显著少于精油中缓释的,说明微乳的缓释性优于精油;在10~30g/L的质量浓度范围内,山苍子精油微乳液标样1比精油表现出更高的1,1-二苯基-2-苦肼基自由基(DPPH·)和2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基(·ABTS^+)清除率,质量浓度30g/L下山苍子精油微乳液标样1的DPPH·和·ABTS^+清除率为95%和54.7%,而山苍子精油的DPPH·和·ABTS^+清除率仅为44.79%和16.4%,说明将山苍子精油制备成微乳可以显著提高其抗氧化性,且微乳对DPPH·的抗氧化性显著优于对·ABTS+的。     

连香树人工幼林群落营养元素含量、积累分配和循环

研究了 1 0年生连香树人工群落 8种营养元素的含量、积累分配和循环。主要结论是 :( 1 )连香树营养器官中各种元素的平均含量顺序为Ca>N >Al>K >Mg>P >Fe >Mn。 ( 2 )元素量在各营养器官的分配顺序为根 >叶 >去皮干 >皮 >枝 ,各元素含量顺序为Ca>N >K >Al>Mg>P >Fe >Mn。 ( 3)连香树群落 8种元素的吸收量、存留量和归还量分别是 72 9 82kg·hm- 2 a- 1 、2 0 6 72kg·hm- 2 a- 1 和 52 3 1 0kg·hm- 2 a- 1 。 ( 4) 51 2 %的归还总K量靠降水淋溶归还 ,其余元素总归还量的 55 7%～ 96 5%靠凋落物归还。Fe、Al归还量的 4 1 3%和 4 4 3%通过死根归还。 ( 5) 8种元素的利用系数、归还比和周转期分别为 0 2 3～ 0 54、0 57～ 0 82和 2 2 6～7 63。文中改进了降水淋溶归还的算法 ,提出了群落归还系数、积累系数和吸收系数 ,讨论了落叶树种元素生物循环的算法