茶多糖金属络合物的制备及清除自由基活性研究

粗老绿茶经弱碱性的大孔阴离子交换树脂D315柱层析分级,得到以酸性糖为主的多糖样品ATPS.将ATPS与金属离子Ca2+、Fe3+络合,制备得到ATPS-Ca(Ⅱ),ATPS-Fe(Ⅲ)络合物.研究发现茶多糖对不同的金属离子配位能力大小不同,ATPS-Ca(Ⅱ)的络合程度远高于ATPS-Fe(Ⅲ).红外光谱扫描发现茶多糖可能以仲羟基和羧基的C-O配位为主.采用化学发光体系产生自由基模型,以比较经金属离子络合后的不同结构的茶多糖清除自由基的能力.研究发现:ATPS及其络合物清除·OH活性远高于O2-,且ATPS-Ca(Ⅱ)清除羟自由基活性比ATPS减弱很多,ATPS-Fe(Ⅲ)清除羟自由基活性与ATPS接近,一方面,这可能与茶多糖ATPS与二价钙的络合程度远远强于与三价铁的络合程度,其清除·OH活性很大程度与络合金属离子位点的数目及络合强度有关,另一方面,可能与·OH相比,茶多糖与O2-的反应活性很弱有关.     

不同处理方法对白刺多糖抗氧化活性的影响

本文研究了不同处理方法对白刺多糖抗氧化活性的影响。实验通过热干、冷干、脱色等方法处理白刺多糖,从清除超氧自由基、DPPH自由基、抑制羟基自由基的产生、还原力4个指标系统地研究了不同处理方法对白刺多糖体外抗氧化活性的影响。经热干、冷干及脱色等不同方法处理得到的白刺多糖,实验所得EC50值小于0.1 mg/m L,总体来说,与经冷干得到的多糖样品相比,热干所得样品抗氧化能力有所下降,这可能是由于在热干过程中由于温度的原因引起多糖活性部分丧失,由实验数据可知经过脱色的样品对清除羟自由基(·OH)和DPPH的能力较强,而对于氧自由基(O_2~-·)的清除和还原力有所下降,相反,未经脱色的样品对氧自由基(O_2~-·)的清除能力和还原力较强,而对羟自由基(·OH)和DPPH的清除能力有所下降。结论:在体外抗氧化实验中,与热干、未脱色的多糖相比,经冷干及脱色处理得到的白刺多糖表现出较好的自由基清除能力,尤其是对超氧自由基(O_2~-·)和DPPH自由基的清除能力,因此,白刺多糖具有较好的抗氧化能力,可作为一种潜在的抗氧化剂运用于食品行业。     

旱莲草多糖的提取及其抗氧化活性研究

采用水/甲醇混合溶剂浸泡提取旱莲草的多糖组分,利用硅胶柱层析和中压液相色谱,对多糖进行分离纯化,纯化后的多糖组分经薄层层析分析发现,这些多糖主要组成单糖均为葡萄糖和果糖。旱莲草多糖在总还原能力、总抗氧化能力和FRAP抗氧化能力测试中均显示较好的活性,能够有效清除羟自由基和DPPH自由基,在1.5 mg/m L的浓度下,对羟自由基的清除效率为(12.33~56.81)%,粗多糖组分在1 mg/m L的浓度下对DPPH自由基的清除效率为(17.88~84.47)%,精分多糖组分在5 mg/m L的浓度下,对DPPH自由基的清除效率为(18.64~91.35)%;极性小的多糖抗氧化活性显著优于极性大的多糖,抗氧化活性最高可达后者的11倍之多;粗多糖组分的抗氧化活性一般优于纯化后的相应精多糖组分,这说明旱莲草的不同多糖分子之间可能存在协同抗氧化作用。     

桦褐孔菌活性物质的提取工艺及体外抗糖尿病活性

对桦褐孔菌活性物质的提取工艺及其体外抗糖尿病活性进行研究。桦褐孔菌子实体用乙醇浸提后,乙醇粗提物用不同有机溶剂萃取,醇提残渣再以热水浸提,用标准曲线法测定活性组分中活性成分的含量,并检测活性物质对羟基自由基(·OH)、超氧阴离子自由基(O2-·)的清除效果以及对关键糖代谢酶α-淀粉酶、α-葡萄糖苷酶的抑制作用。结果表明:4种活性组分(乙酸乙酯相、正丁醇相、水相和粗多糖)对羟基自由基(·OH)和超氧阴离子自由基(O2-·)都有较强的清除作用,其中乙酸乙酯组分的活性最高,乙醇粗提物萃取组分对α-淀粉酶有抑制活性,而粗多糖对α-葡萄糖苷酶有抑制作用;桦褐孔菌具有抗氧化和抗糖尿病活性,其活性与活性物质种类及其含量具有相关性。     

超声参数对白术多糖抗氧化活性的影响

采用热水浸提和超声辅助法提取白术多糖,研究白术多糖的总还原能力以及对超氧阴离子(O2-·)、羟基自由基(·OH)、1,1-二苯基-2-苦苯肼自由基(DPPH·)的清除作用.结果表明:超声频率80 kHz,功率220 W时,白术多糖提取率达到最大(8.017％),明显高于热水浸提法所得(6.832％).白术多糖对·OH和DPPH·具有较强的清除作用,随着质量浓度的升高,·OH清除率呈上升趋势.超声功率和频率均对白术多糖的抗氧化活性有影响且超声功率的影响较大.随着超声功率的提高,白术多糖清除·OH的能力增强,但对O2-·的清除能力影响较弱.     

冬葵果多糖的抗氧化作用研究

研究冬葵果多糖(Fructus Malvae polysaccharides,FMP)对氧自由基的清除作用及对脂质过氧化的抑制作用。采用分光光度法测定FMP清除Fenton体系产生的羟自由基(.OH)、邻苯三酚自氧化体系产生的超氧阴离子自由基(O2-.)的能力及评价对Fe(Ⅱ)-H2O2体系(.OH)诱导的脂质过氧化终产物丙二醛(MDA)的抑制作用。结果显示,在化学模拟体系中,冬葵果多糖对.OH具有很强的清除作用,与VC比较达到显著水平(P<0.01),对O2-.的清除能力与VC相当。在体外,多糖浓度达到1.72 mg/mL可明显降低MDA的含量,与空白液比较达到显著水平(P<0.01)。以上结果表明,FMP具有明显的抗氧化活性。     

杨桃提取物体外清除氧自由基作用

从杨桃果中提取得到三种提取物为匀浆提取物、蛋白提取物和多糖提取物。采用化学发光法测定这三种提取物清除氧自由基的活性,实验结果:匀浆提取物清除羟自由基(·OH)和H2O2的活性大小相近,而清除超氧阴离子自由基(O2–·)的活性较小,其IC50约为前两者的4倍。蛋白提取物清除O2–·和·OH的活性大小相近,而清除H2O2的活性明显小于前两者,IC50约为前两者的9倍。多糖提取物清除.OH的活性明显大于清除O2–·和H2O2的活性,其IC50约为O2–·的1/22,约为H2O2的1/65。结果表明,杨桃果具有清除O2–·、·OH和H2O2的作用,不同提取物对这些活性氧自由基的清除能力有所不同。     

野木瓜水溶性多糖的分离纯化及抗氧化活性研究(英文)

采用水提醇沉法获得了水溶性野木瓜粗多糖(CCCPs),经过脱蛋白、脱色及透析,得到了野木瓜精多糖(FCCPs),再经DEAE-纤维素和Sepharose CL-6B柱层析得到均多糖组分(CCP1)。高效液相色谱法测定CCP1的单糖组成为:鼠李糖、阿拉伯糖、果糖、甘露糖、葡萄糖,其摩尔比为0.034∶0.228∶0.045∶0.055∶0.638。体外抗氧化实验结果表明:不同纯度的野木瓜多糖都具有一定的抗氧化活性,并且随着多糖浓度增加,抗氧化活性增强,野木瓜粗多糖(CCCPs)对·OH和O-·2的清除能力比精多糖(FCCPs)和均多糖(CCP1)强。     

斜链拟青霉多糖活性组分的分离及其清除自由基活性

对斜链拟青霉胞外多糖进行体外清除自由基活性研究。利用醇沉法从斜链拟青霉发酵液中醇沉获得斜链拟青霉胞外多糖,经DEAE-纤维素-52柱层析后得到1个主峰P3和2个小峰P1与P2,对主峰P3进行Sephadex G-100柱层析,表明P3为纯化物; 应用DPPH-酶标法和化学发光法分别对P3进行清除DPPH·、·OH和O-2·能力测试。结果表明：P3对DPPH·、·OH和O-2·均具有明显的清除能力,且与浓度呈量效关系,IC50分别为0.083、0.121和0.214 mg/mL。     

软枣猕猴桃果实多糖提取工艺优化及其抗氧化研究

目的：为优化软枣猕猴桃果实多糖的超声辅助离子液体提取工艺，并评价抗氧化活性。方法：采用单因素和响应面试验探究最佳提取工艺，测定DPPH自由基（DPPH·）和羟自由基（·OH）清除能力以及总还原能力。结果：确定最佳提取工艺为：[BMIM]Br的浓度为0.5 mol/L，液料比35:1(mL/g)，超声功率为350 W，超声时间为70 min，该条件下软枣猕猴桃果实多糖的提取率为3.52%。去除DPPH·的能力为：SPS60>SPS30>SPS，去除·OH的能力为：SPS60>SPS30>SPS，并且SPS60的总还原能力高于SPS30和SPS。结论：SPS60具有更强的体外抗氧化能力，开发前景广阔。     

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.