木奶果醇提物的抗氧化活性及其对Aβ25-35致PC12细胞损伤的神经保护作用

为了探明木奶果不同部位的总酚含量和抗氧化活性及其对Aβ25-35致PC12细胞损伤的神经保护作用的差异,以期为木奶果高价值产品开发提供理论依据。以木奶果果皮、果肉、果核3个部位醇提物为研究对象,采用Folin-Ciocalteu法、DPPH、ABTS、羟基自由基清除能力测定体外抗氧化活性,并采用Aβ25-35诱导PC12细胞成阿尔兹海默病细胞模型测定醇提物对不同浓度Aβ25-35所致PC12细胞损伤的神经保护作用。结果显示:木奶果果皮、果肉、果核3个部位的总酚含量分别为(101.03±5.99)、(16.03±1.13)、(51.27±4.02)mg GAE/g干物质;抗氧化活性与样品浓度存在剂量关系,其中果皮的抗氧化活性最强,果核次之,果肉最差;果皮醇提物对Aβ25-35所致PC12细胞损伤的神经保护作用最佳,当木奶果果皮醇提物浓度为1 mg/m L时,能将Aβ25-35诱导的PC12细胞致死率从(41.6±1.36)%降为(11.95±1.98)%;PC12细胞的凋亡率从(84.69±5.78)%降至(25.26±3.18)%。可见,木奶果醇提物对Aβ25-35所致PC12细胞氧化损伤具有很好的保护作用。     

火龙果茎多糖的超高压提取及抗氧化活性研究

为研究火龙果茎多糖的超高压提取工艺及抗氧化活性。在单因素试验基础上,采用Box-Behnken设计和响应面分析方法,确定超高压提取的最优工艺,并从清除ABTS自由基和DPPH自由基能力方面来评价火龙果茎多糖的体外抗氧化能力。结果表明,火龙果茎多糖的超高压提取的最佳工艺条件为:液固比10∶1(m L∶g)、超高压压力300 MPa、超高压时间4 min。在此工艺条件下多糖得率为(2.83±0.02)%。火龙果茎对ABTS自由基和DPPH自由基具有清除作用,对ABTS自由基和DPPH自由基的清除率IC_(50)分别为浓度为4.3 mg/m L和5.5 mg/m L时。     

大孔树脂纯化白背天葵多酚及其体外抗氧化研究

为了分离纯化白背天葵多酚,并探讨其体外抗氧化活性,本研究比较了8种大孔树脂对白背天葵多酚的静态吸附和解吸能力,优选出D101为最适宜纯化白背天葵多酚的树脂,并对其分离纯化的工艺进行了优化。采用DPPH和ABTS法评价其抗氧化活性。结果表明,D101树脂最佳纯化工艺为上样液浓度1 mg/mL、pH 3.1、上样液流速2 mL/min,解吸的乙醇体积分数70%、体积60 mL、流速2 mL/min;白背天葵多酚的含量由14.73%提高到45.21%;其清除DPPH及ABTS自由基的能力为 Vc>纯化物>粗提物。研究结果为进一步开发利用白背天葵多酚提供了数据支持。     

牛蒡子75%乙醇提取物总酚含量及抗氧化活性研究

目的本文主要测定牛蒡子75%乙醇提取物的体外抗氧化活性。方法:采用ABTS自由基、DPPH自由基清除方法以及还原法和总酚含量测定法,并利用紫外分光光度计法测定牛蒡子乙醇提取物的抗氧化活性。结果牛蒡子醇提物对DPPH、ABTS+自由基的清除率IC50值分别为0.055mg/m L、0.121 mg/m L;当浓度为1.24 mg/m L水平,其吸光度值为2.390,显示较强的还原性,其中总酚含量为48.3μg/mg。结论牛蒡子的75%醇提取物具有较好的抗氧化活性,在天然抗氧化剂的食品保鲜和药物的治疗方面,牛蒡子的醇提取物可以作为一种新的抗氧化材料,应用价值较好。     

苦丁茶不同提取物抗氧化活性比较及其GC-MS分析

利用气相色谱-质谱联用技术（GC-MS）,对苦丁茶超声辅助不同有机溶剂（乙醇、乙酸乙酯、石油醚）提取物及超临界CO₂萃取物的体外抗氧化活性（DPPH自由基清除能力、羟基自由基清除活性、超氧阴离子自由基清除活性和ABTS ⁺自由基清除能力）进行比较分析。结果表明,苦丁茶不同提取物DPPH清除能力和超氧阴离子自由基清除活性依次为：超声-乙醇提取物>超临界CO₂萃取物>超声-乙酸乙酯提取物>超声-石油醚提取物,羟基自由基和ABTS ⁺自由基清除能力依次为：超声-乙醇提取物>超声-乙酸乙酯提取物>超临界CO₂萃取物>超声-石油醚提取物。GC-MS结果显示,苦丁茶不同提取物中主要有5类物质,共有49种化学成分,7种共有成分。     

大麻叶中总黄酮提取工艺的优化及其抗氧化活性测定

为优化大麻叶总黄酮提取工艺并评估大麻叶总黄酮抗氧化活性,研究在单因素试验基础上,以提取时间、提取温度、料液比和乙醇体积分数为影响因素,总黄酮浸提量为评价指标,采用响应面试验设计优化提取工艺。采用FRAP总抗氧化能力测定试验、DPPH自由基清除试验以及ABTS自由基清除试验对总黄酮提取物进行抗氧化活性评价。结果表明:提取大麻叶总黄酮的最佳工艺条件为乙醇体积分数50%、料液比1∶20(g/m L)、提取时间2.0 h、提取温度70℃。在该最优提取条件下,大麻叶总黄酮浸提量为14.28 mg/g。抗氧化试验表明,大麻叶总黄酮的总抗氧化能力相当于1.288 mmol/L Fe SO4,对DPPH自由基的清除能力(IC50=3.7μg/m L)低于VC的清除能力(IC50=2.3μg/m L),而对ABTS自由基的清除力相当于0.391 mmol/L的Trolox。该工艺提取大麻叶得到的总黄酮含量较高,且具有一定的抗氧化性,可为未来大麻叶总黄酮的开发提供一定的科学依据。     

紫薯花色苷的提取及抗氧化活性研究

以紫薯‘济黑’为原料,酸化乙醇为溶剂提取其中的花色苷成分,单因素实验探讨不同因素对提取效果的影响,并通过响应面法建立二次多项数学模型,确定紫薯花色苷最佳浸提条件为:乙醇浓度60%、浸提时间127 min、液料比18∶1,该条件下紫薯花色苷实际浸提值为2.680 mg/g。以VC作为对照,从DPPH自由基、超氧阴离子自由基(O2·-)、羟自由基(·OH)清除率及总抗氧化活性4个方面考察了紫薯花色苷的体外抗氧化能力,结果表明,紫薯花色苷粗提物对DPPH、O_2~-·和·OH均有较好的清除活性,其IC50值分别为1.245、332.291和70.830 mg/L,均小于VC的IC50值,紫薯花色苷粗提物的总抗氧化能力为101.38 U/mg,具有较强的抗氧化活性。     

白背天葵多酚的提取及其抗氧化活性

本文研究了白背天葵多酚的超临界CO₂提取工艺及其体内外抗氧化活性,为白背天葵的开发利用提供依据。以萃取压力、萃取时间、萃取温度、CO₂流量和夹带剂浓度为单因素,以多酚提取得率为指标,采用响应面法对提取工艺条件进行优化。采用体外抗氧化活性试验分析提取物对DPPH及ABTS自由基的清除能力。体内抗氧化活性试验以D-半乳糖致衰小鼠为模型,白背天葵多酚提取物150、300、600 mg/kg连续灌胃30 d,测定其血清及肝组织中超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量。结果表明,白背天葵多酚的超临界CO₂最优提取工艺为萃取压力35 MPa、萃取时间2 h、萃取温度40 ℃、CO₂流量20 L/h,多酚提取得率为5.32%。体外抗氧化试验表明,多酚对DPPH及ABTS自由基的清除率随其浓度的提高而提高。与空白组比较,衰老模型组血清及肝组织中的SOD、GSH-Px、CAT活性显著性降低,MDA含量显著性升高,白背天葵多酚提取物能显著提高衰老模型组血清及肝组织中的SOD、GSH-Px、CAT活性,并降低MDA含量。     

胡椒叶抗氧化物质提取条件初探

采用系统溶剂提取法处理胡椒叶,确定了胡椒叶的乙醇提取相和水提取相具有较强的DPPH自由基清除能力和较高的多酚含量;通过对胡椒嫩叶、完全稳定叶和老叶的乙醇和水提取液的DPPH自由基清除能力和多酚含量的测量,得出胡椒嫩叶的多酚含量较高,抗氧化活性较高,老叶次之;采用不同浓度的乙醇水溶液常温搅拌浸提胡椒老叶,得出50%左右的乙醇水溶液提取液具有较强的清除自由基能力,较高的多酚含量(5.4 g/100g)和黄酮类化合物含量(0.8 g/100g)。     

树仔菜中多酚物质的提取工艺及其清除DPPH的抗氧化作用的研究

为研究树仔菜中多酚物质的提取工艺条件并测定其提取物清除DPPH的抗氧化活性,通过单因素试验,分析不同浸提溶剂、料液比、浸提时间、浸提温度对树仔菜多酚提取量的影响,通过正交试验确定树仔菜多酚的最佳提取条件。结果表明：提取剂为蒸馏水,料液比1∶25,提取温度30℃,提取时间8 h。提取条件下,树仔菜平均多酚提取量达到17.45 mg/g;80%甲醇树仔菜提取物对DPPH自由基清除率达到93.66%,明显高于BHT。采用正交试验法优化了树仔菜多酚提取工艺条件,提升了树仔菜多酚提取量,同时树仔菜提取物具有较好的抗氧化作用。     

NR/ENR/SiO_2复合材料的阻尼性能研究

采用机械混炼的方法制备不同ENR含量的NR/ENR/SiO2复合材料,使用动态热机械分析仪(DMA)和橡胶加工分析仪(RPA)对NR/ENR/SiO2复合材料的动态力学性能和阻尼性能进行分析。结果表明:ENR对NR/ENR/SiO2复合材料的阻尼性能具有显著影响。动态热机械分析测试结果表明,随着ENR用量的增多,NR/ENR/SiO2复合材料在使用温度范围内的损耗因子积分面积增大,阻尼性能提高。橡胶加工分析频率扫描和应变扫描测试结果表明,在频率小于10 HZ不同应变时,加入了ENR的NR/ENR/SiO2复合材料的阻尼因子均高于NR/SiO2复合材料。扫描电镜分析结果证实,ENR的加入减少了SiO2的自聚,改善了填料在橡胶基体中的分散,从而使NR/ENR/SiO2复合材料力学性能得到提高。     

纳米TiO_2/天然橡胶复合材料的抗菌性研究

采用溶胶凝胶法,以钛酸四丁酯掺杂金属Ag制备纳米二氧化钛(Ag-TiO2)水溶胶,并与天然胶乳湿法共混制备得到纳米TiO2/天然橡胶复合材料。紫外可见光谱表明,金属Ag能提高TiO2的光催化性能;透射电子显微镜观察到TiO2颗粒粒径为50nm左右,并且均匀的吸附在胶粒表面。研究此复合材料的抗菌性能结果表明,其具有良好的抗细菌和抗霉菌效果,对大肠杆菌的抗菌率达到90%以上,特别是硫化过后的纳米TiO2/天然橡胶复合材料的抗细菌率更达98.5%。     

In VitroDigestion of Wheat Microstructure with Xylanase and Cellulase fromTrichoderma reesei

Resistant starch (RS), producedin vitroby hydrolysis of retrograded pea starch gels and amylose gels by porcine pancreaticalpha-amylase, was characterised by X-ray diffraction, size exclusion chromatography and methylation analysis. These techniques showed that RSin vitroconsisted of semi-crystalline, mostly linear material that was present in two main molecular size subfractions (DP_n>100 andDP_n20–30) with a third, minor subfraction (DP_n≤5). The extent of retrogradation of amylose was found to be of primary importance in determining the RS content of starch. Analysis ofin vivoRS, recovered during an ileostomy study, produced results that were similar to those obtained from RSin vitro. Anin vitromodel for the structure of resistant starch is proposed.     

Physicochemical Studies on Resistant StarchIn VitroandIn Vivo

Resistant starch (RS), producedin vitroby hydrolysis of retrograded pea starch gels and amylose gels by porcine pancreaticalpha-amylase, was characterised by X-ray diffraction, size exclusion chromatography and methylation analysis. These techniques showed that RSin vitroconsisted of semi-crystalline, mostly linear material that was present in two main molecular size subfractions (DP_n>100 andDP_n20–30) with a third, minor subfraction (DP_n≤5). The extent of retrogradation of amylose was found to be of primary importance in determining the RS content of starch. Analysis ofin vivoRS, recovered during an ileostomy study, produced results that were similar to those obtained from RSin vitro. Anin vitromodel for the structure of resistant starch is proposed.     

细旦涤麻棉针织物的纤维素酶整理

本文介绍了酶整理技术在细旦涤麻棉针织物上的应用，提出了现在主要三种纤维素酶处理细旦涤麻棉针织物的最佳工艺及效果。     

巴西橡胶树AnnHb1基因的克隆及表达分析

根据一个从巴西橡树胶乳cDNA文库中获得的EST片段的序列设计引物,通过RACE的方法获得了橡胶树编码annexin的cDNA,命名为AnnHb1。序列分析表明,AnnHb1长为1 198 bp,含有945 bp的阅读框,62 bp的5'-UTR和191 bp的3'-UTR,编码314个氨基酸,分子量为35.99 ku,等电点为8.18。该氨基酸序列与蓖麻、麻疯树、棉花、苜蓿、烟草和拟南芥中的annexin的同源性分别为82%、72%、72%、64%、60%和60%。半定量RT-PCR分析结果表明AnnHb1基因在愈伤、花、树皮、叶、胶乳中均有表达,其中在愈伤组织中表达量最低,树皮中表达量最高。     

Polymorphism of Low Mr Glutenin Subunits in Triticum tauschii

A collection of 173 Triticum tauschii accessions was analysed to evaluate the variability of low molecular weight (M_r) glutenin subunits. These proteins were analysed by one-step one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and were divided into B-, C- and D-subunits in accordance with their electrophoretic mobility. Extensive polymorphism, both in the number and electrophoretic mobility, was detected in lowM_r glutenin subunits present in T. tauschii. Thirty different patterns for B-subunits and forty-three for C-subunits were identified, some of which were with identical electrophoretic mobility than those observed in hexaploid wheat. Glutenin subunits with the same electrophoretic mobilities of low M_r D-glutenin subunits as well as subunits encoded at the Glu-D4 and Glu-D5 loci, were also detected in accessions of T. tauschii. These results provide new basic knowledge regarding the genetics variability of the low M_r glutenin subunits, as well as their potential to create novel germplasm for the improvement of wheat quality in breeding programs.     

Comparative Enzyme Kinetics of Two Allelic Forms of Barley (Hordeum vulgare L.) Beta -amylase

The barley (Hordeum vulgare L.) varieties, Franklin and Schooner, contain two different allelic forms of beta -amylase (EC 3.2.1.2) encoded on chromosome 4H by the Bmy 1-Sd1 and Bmy 1-Sd2L alleles, respectively. The corresponding enzymes, referred to as Sd1 and Sd2L, were purified from both mature barley grain and germinated barley (green malt), and their physical and kinetic properties studied. Approximately 4 kDa were cleaved from both Sd1 and Sd2Lbeta -amylases after germination. The K_mvalue for green malt beta -amylase was less than that of mature grain beta -amylase for both varieties when potato starch was used as a substrate, although V_maxwas similar. This indicated that proteolysis after germination increased the affinity of beta -amylase for potato starch. No significant kinetic differences were observed between beta -amylase from mature grain and green malt of the two barley varieties when amylose (degree of polymerisation 100 and 18) and maltopentaose were used as substrates. Kinetic differences were also observed between the two allelic forms of beta -amylase. Sd1 beta -amylase from green malt exhibited a lower K_mvalue for potato starch than Sd2L beta -amylase, demonstrating that at non-saturating starch concentrations Sd1 beta -amylase is better able to hydrolyse starch than Sd2L beta -amylase. As the degree of polymerisation of the substrates decreased from approximately 740 (potato starch) to 5 (maltopentaose), the K_mvalues for beta -amylase increased, whereas V_maxvalues decreased. Maltose, the hydrolytic product of beta -amylase, was found to be a weak competitive inhibitor of both Sd1 and Sd2L green malt beta -amylases with respect to potato starch and amylose. Taken together the kinetic observations for bet a-amylase suggest that the allelic differences and C-terminal proteolysis might be exploited to improve the efficiency of starch hydrolysis during the mashing stage of the brewing process.     

杜鹃红山茶离体快速繁殖

以杜鹃红山茶实生小苗为试验材料,探讨离体快速繁殖的方法。结果表明:茎段外植体在MS+BA 1 mg/L+IBA 0.01 mg/L+GA3 10 mg/L的培养基上培养60 d,侧芽萌发率高达68%;将这些萌发的侧芽连同原来的茎段外植体移至添加BA 0.2～0.4 mg/L的培养基培养1个月,74%的侧芽能够继续生长并形成丛生芽;再将丛生芽移至1/2 MS+IBA 4 mg/L+0.1%活性炭的培养基上培养1个月,得到大量伸长的芽条;将芽条切离母体后插植于1/2 MS+IBA 8 mg/L的培养基,60 d后生根率达到90%。通过以上过程繁殖得到的小苗质量良好,移栽1个月后的成活率可达90%。     

Protein Inhibitors ofAlpha-amylase in Mature and Germinating Grain of Rye (Secale cereale)

The activities of endogenous (R-type) and exogenous acting (D-type) protein inhibitors ofalpha-amylase and the activities ofalpha- and total amylase were determined in milling fractions of rye. High D-type amylase inhibitor activities were detected in the embryo (255 IU/g) and in the endosperm fraction (64·9 IU/g), low inhibitor activities were found in the aleurone layer fraction (25·9 IU/g). The highest R-typealpha-amylase inhibitor activity was found in the aleurone layer fraction (32·6 IU/g), and the lowest value in the epidermis containing fraction (5·0 IU/g). The D- and R-typealpha-amylase inhibitor activities varied with growing conditions. D-type amylase inhibitor activities were found to be high in those samples which grew under drought conditions and low in samples cultivated under wet and cool weather. Higher R-typealpha-amylase inhibitor activities were found in rye genotypes cultivated under wet conditions and lower values under dry weather. There were small variations inalpha-amylase inhibitor activities between sprout-stable and sprout-sensitive rye genotypes. The D- and R-typealpha-amylase inhibitor activities of all varieties were stable during 72 h of germination. Similar soil conditions will therefore lead to differentialalpha-amylase inhibitor activities depending on weather conditions during growth.