青橄榄浸膏的提取及其抗氧化活性研究

为优化青橄榄浸膏提取工艺,并探讨其抗氧化性。以茂名盛产的青橄榄为原料,采用超声波辅助乙醇提取法,以总黄酮和总多酚得率为评价指标,考察各因素对青橄榄浸膏提取效果的影响。采用邻苯三酚自氧化法、结晶紫法和DPPH清除能力评价青橄榄浸膏的抗氧化活性。结果显示,浸膏的最佳提取工艺为:乙醇体积分数70%,料液比1∶18 (g∶mL),超声提取温度50℃,时间6 min(超声提取阶段);单纯有机溶剂提取温度60℃,时间45 min(有机溶剂浸提阶段);此条件下总黄酮得率为1. 76%,总多酚得率为15. 53%。终产物浸膏在0. 3 mg/mL浓度下对超氧阴离子自由基抑制率为22. 74%,相当于同等质量浓度的抗坏血酸抑制效果的23. 47%;在0. 02 mg/mL浓度下对羟基自由基的清除率为67. 32%,相当于同等质量浓度的抗坏血酸清除效果的112. 58%;在0. 2 mmol/mL的DPPH溶液体系中,0. 15 mg/mL的浸膏对DPPH的清除率为95. 40%,相当于同等质量浓度的抗坏血酸清除效果的140. 83%;总体来讲,浸膏具有良好的抗氧化能力,虽然对超氧阴离子自由基抑制率弱于抗坏血酸,但羟基自由基的清除率及DPPH清除率均优于抗坏血酸。     

响应面法优化金莲花总酚酸的提取工艺及其美白活性研究CSCD

采用响应面分析法中Box-Behnken设计实验优化乙醇回流提取金莲花总酚酸的工艺条件,同时研究了金莲花总酚酸对DPPH自由基、羟基自由基的清除能力、还原能力及其对酪氨酸酶的抑制作用。结果表明,金莲花总酚酸的最佳提取工艺为乙醇浓度60%,回流时间90 min,回流温度60℃,液料比40∶1(mL/g);在此条件下金莲花总酚酸得率为92.245 mg/g。此外,其对DPPH自由基、羟基自由基具有一定的清除能力和还原能力,并且能够显著性地抑制酪氨酸酶活性。本研究所得的提取工艺稳定可靠,金莲花总酚酸具有一定的体外抗氧化活性和酪氨酸酶抑制作用,为进一步科学合理开发利用金莲花奠定基础。     

广东石豆兰多糖的提取工艺及其抗氧化活性

为优化广东石豆兰多糖的提取工艺并评价其抗氧化活性。在单因素试验基础上,采用正交设计和方差分析,研究液料比、提取温度、时间及沉淀多糖的乙醇浓度对石豆兰多糖浸提量的影响并优化了工艺条件,确定最优条件为液料比50∶1 (mL/g),提取温度90℃,时间6 h,醇沉浓度为95%,此条件下多糖提取量为79.060 mg/g,RSD为0.132%。抗氧化结果表明广东石豆兰多糖的总还原力为L-抗坏血酸的3.46%;对DPPH、·OH、·O■自由基半清除浓度(EC₅₀)分别为2769.58、594.60、586.94μg/mL,其清除能力分别是L-抗坏血酸的0.68%、47.17%和29.00%;对Fe²⁺的半螯合浓度(EC₅₀)为160.83μg/mL,螯合能力是EDTA的2.12%。本研究结果为石豆兰多糖的提取及进一步开发利用提供参考依据。     

紫皮石斛总酚提取工艺优化及其抗氧化活性研究

目的：研究紫皮石斛总酚提取工艺及体外抗氧化活性。方法：在单因素试验的基础上，采用响应面法优化紫皮石斛总酚的超声波辅助提取工艺条件，通过测定紫皮石斛总酚对超氧阴离子、DPPH自由基及羟自由基的清除率，评价其抗氧化活性。结果：紫皮石斛总酚最优提取工艺条件为乙醇浓度69%，料液比1∶40 (g/mL)，提取时间31 min，在此条件下总酚提取量为1.56 mg/g，与理论值1.58 mg/g接近。紫皮石斛总酚对超氧阴离子、羟自由基及DPPH自由基的半数抑制浓度(IC₅₀)分别为19.40μg/mL、118.35μg/mL及30.75μg/mL。结论：优选的紫皮石斛总酚提取工艺合理可行，且其具有较强的体外抗氧化活性。     

纳豆多糖发酵工艺的优化及清除自由基研究

考察了纳豆菌接种量、料液比、发酵温度及发酵时间对纳豆菌发酵豆粕产生的纳豆多糖得率的影响,进行了响应面设计实验,得出最佳发酵工艺参数;探究了纳豆多糖的抗氧化活性,并与维生素C进行比较。实验结果表明:接种量为0. 6%,料液比为1∶3,发酵温度40℃,发酵时间48 h,在此工艺条件下水溶性纳豆多糖得率最高为4. 371%。纳豆多糖浓度为1. 5 mg/mL时,对羟基自由基的清除率是50. 07%,对超氧阴离子自由基的清除率达95. 79%,对DPPH自由基的清除率为16. 35%。     

新疆戈宝麻叶中芦丁的优化提取工艺

采用乙醇回流提取法提取戈宝麻叶中芦丁,高效液相层析法测定戈宝麻叶中芦丁含量,通过响应面法优化新疆戈宝麻叶中芦丁的提取工艺,提高芦丁得率。在提取温度、提取时间、提取次数、提取温度、料液比等单因素试验的基础上,采用响应面法建立芦丁得率的数学回归模型,分析了模型的有效性、单因素效应及各因素间的交互作用。响应面法优化后芦丁提取最佳工艺条件如下:提取时间为2.080 h、料液比为1∶14.866 (g∶mL)、提取3次、提取温度为60℃、乙醇浓度为86.189%,在此工艺条件下戈宝麻中芦丁理论得率为0.685%,实际结果得率为0.677%,与模型预测值吻合度高,说明该模型切实可靠,为戈宝麻叶中芦丁的加工利用提供了试验基础。     

莞香叶及成茶中黄酮类化合物的提取及其对亚硝酸盐的清除率研究

以莞香茶成茶和新鲜莞香叶为原料,乙醇超声辅助提取莞香茶中的黄酮类化合物,考察液料比、提取温度、提取时间、乙醇浓度等条件对黄酮类化合物得率的影响。结果表明,莞香茶黄酮类化合物的最优提取条件为:液料比为20∶1(mL∶g),提取温度为60℃,提取时间为3.5 h,乙醇浓度为60%。后采用紫外分光光度法测定莞香茶中黄酮类化合物在模拟胃液条件下对亚硝酸盐的清除率。试验结果表明,莞香茶中黄酮得率与新鲜莞香叶相比有上升也有下降,但下降幅度均不超过5%;3个品牌中黄酮对亚硝酸盐的清除能力也均有下降,但下降幅度不超过13%。     

黑小豆种皮花色苷的提取及体外抗氧化活性研究

为了探索新的花色苷资源,以黑小豆种皮为原料,对其花色苷类色素的提取工艺进行了研究。通过单因素和L_9(3~4)正交试验,考察了乙醇浓度、料液比、温度和p H对粗提液中花色苷含量的影响。结果表明,最佳提取条件为:乙醇浓度60%、料液比1∶20(g∶m L)、温度50℃、p H=2.0。此条件下,黑小豆种皮粗提液中花色苷的含量最大(5.912 mg/g);黑小豆种皮花色苷粗提物得率为19.1%,纯度为3.06%;粗提物具有一定的总抗氧化能力和清除O~(-·)_2、·OH和DPPH自由基的能力。黑小豆种皮可作为一种新型花色苷资源加以利用。     

超声辅助提取四齿四棱草中总黄酮及其抗氧化活性

本文采用正交实验优选超声辅助提取四齿四棱草中总黄酮的最佳工艺,测定其含量,并以Vc为对照,采用DPPH法、ABTS法和FRAP法对四齿四棱草总黄酮抗氧化活性进行综合评价。通过单因素实验和正交实验,研究乙醇浓度、超声时间、料液比、提取温度对四齿四棱草中总黄酮提取率的影响,优选出超声辅助提取四齿四棱草总黄酮的最佳工艺:乙醇浓度为70%,料液比为1∶30 g/m L,50℃超声提取两次,每次30 min,四齿四棱草总黄酮提取率为4.78%。四齿四棱草总黄酮对DPPH自由基(IC_(50)=42.91μg/m L,最大清除率为88.57%)、ABTS自由基(IC_(50)=44.61μg/m L,最大清除率为92.86%)的清除能力较好,对Fe~(3+)的还原能力(AEAC=5380μmol/g)亦较强,是一种天然的抗氧化剂。     

均质剪切辅助响应面法提取扛板归总黄酮及其抗氧化性能研究

为了研究扛板归中总黄酮的最佳提取工艺及其体外抗氧化活性,在高剪切及回流提取单因素的基础上,采用响应面法考察了回流温度、回流时间、料液比、乙醇浓度对提取率的影响。结果显示,扛板归总黄酮最优提取工艺为:回流温度79.86℃,回流时间2.03 h,乙醇浓度51.64%,料液比1∶59(m∶V),剪切次数7次,剪切温度50℃。最优工艺下总黄酮的提取率为8.37%。提取的总黄酮抗氧化性能良好,浓度为8 mg/mL时,对DPPH·、O■和·OH三种自由基的清除率在68%～90%之间。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.