酶解法提取纯化虎杖提取物中自藜芦醇的工艺研究

本文对虎杖提取物中虎杖苷的酶解条件及苷元白藜芦醇的提取纯化工艺进行研究,以样品中自藜芦醇的含量为指标,对纤维素酶、β-葡萄糖苷酶、复合酶进行筛选,结果表明以复合酶的水解效率最高:采用正交实验对影响复合酶酶解的因素:加酶量、温度、酶解时间进行考察;并对酶解后提取物中自藜芦醇的提取纯化工艺进行研究.得出如下较理想的酶解条件和提取纯化工艺:虎杖提取物,加水(pH 5)10倍,加20%的复合酶,于50℃保温24 h;酶解后的提取物经水、乙醇-水、碱溶液分步溶解沉淀,得白藜芦醇粗品,含量可达65%,工艺稳定可行.     

UV-C和水杨酸对虎杖叶中白藜芦醇和虎杖苷的诱导作用

以不同叶龄虎杖叶为材料,研究了不同剂量紫外线(UV-C)和10mmol/L水杨酸(SA)处理对叶中白藜芦醇和虎杖苷含量的影响。结果显示:2.4kJ/m2UV-C照射并经暗处理36h后可使虎杖嫩叶中白藜芦醇含量增加近1倍,暗处理24h后虎杖苷含量提高了30%以上,但是老叶中两者含量没有显著变化。SA处理48h后,嫩叶中白藜芦醇的含量提高约5倍,同时虎杖苷的含量下降了60%并且伴随着一个新成分的产生;老叶中白藜芦醇提高约2倍,虎杖苷的含量则没有显著变化。研究表明SA和UV-C对不同叶龄的虎杖叶片中白藜芦醇和虎杖苷合成均有诱导作用,且嫩叶比老叶表现得更为明显。     

虎杖中白藜芦醇的酶法制备

以白藜芦醇得率为指标,通过对酶制剂的筛选和酶解条件的考察,分别选出酶法提取和酶法转化制备虎杖中白藜芦醇的最佳条件,并对两种酶法进行比较.结果显示:(1)酶法提取最佳酶解条件为:酶解温度45℃,酶解时间60 min,最适pH 5.0,底物浓度17%;酶法转化最佳酶解条件为:酶解温度40℃,酶解时间48 h,最适pH 5.0,底物浓度15%.(2)与空白样品(不加酶)相比,酶法提取白藜芦醇得率增加了3.12 mg/g;酶法转化白藜芦醇得率增加了12.72 mg/g.研究表明,两种方法与不加酶提取相比均提高了白藜芦醇的得率,但酶法转化效果更显著,可用于白藜芦醇的制备.     

酶法提取葡萄穗轴中原花色素、白藜芦醇的研究

将纤维素酶用于葡萄穗轴中原花色素和白藜芦醇的提取工艺中.即在乙醇提取前,先用纤维素酶处理葡萄穗轴粗粉.通过实验确定最佳的酶解条件为:酶解体系pH 6,酶解温度30 ℃,酶解时间80 min,m(纤维素酶):m(葡萄穗轴粗粉)=1∶ 250.实验还对酶解后乙醇提取条件进行优化:40%乙醇溶液为提取剂,提取温度80 ℃,提取时间120 min.提取液通过溶剂萃取进行分离,用香草醛-盐酸法和紫外分光光度法分别测定其中原花色素和白藜芦醇的含量.与传统直接醇提法相比,原花色素的提取率提高了近4倍,白藜芦醇的提取率也有所提高.     

树脂法提取纯化白藜芦醇的新工艺研究

对虎杖中的白藜芦醇先酶解再提取,提取液采用一种新树脂进行纯化分离。考察了酶解物、不同树脂、上柱量、洗脱量等因素对白藜芦醇提取纯化的影响,确立了白藜芦醇的最佳提取纯化条件:用酿酒曲于35~40℃将原药材先酶解24 h,再用75%乙醇提取,提取液经回收乙醇后上XC-7大孔树脂柱,先加10%乙醇洗脱,然后再用60%乙醇洗脱并收集洗脱液,浓缩,真空干燥即可,产品中白藜芦醇含量达85%,白藜芦醇转化率达85%以上。     

大孔吸附树脂分离虎杖中白藜芦醇的研究

目的:采用大孔吸附树脂对虎杖粗提物中白藜芦醇进行初步富集、分离和纯化.方法:考察18种树脂对白藜芦醇的吸附量和解吸率,选择吸附量大、解吸率高的数种树脂进行吸附动力学研究,确定最佳的脱附工艺.结论:HPD-500树脂对白藜芦醇的吸附量可达58.67mg/g,解吸率为92.6%,经大孔吸附树脂的吸附与解吸,白藜芦醇的含量由粗提物中9.25%提高至39.5%.     

两种不同植物来源白藜芦醇生物合成关键酶——芪合酶催化效率比较

白藜芦醇是一种天然植保素,且具有特殊的药理和保健功能,芪合酶(Stilbene synthase,STS)是该化合物生物合成的关键酶和限速酶。白藜芦醇存在于有限几种植物且含量差异很大,虎杖中白藜芦醇含量比葡萄、花生高1 000倍以上,推测不同STS的催化能力有可能是白藜芦醇含量差异的原因之一。为验证上述推测,文中通过overlap PCR技术从葡萄叶片基因组DNA中克隆得到葡萄STS基因,连同前期工作中获得的虎杖STS基因(PcPKS5),进行了原核表达分析。诱导表达产物经过Ni2+亲和柱纯化和PD-10柱脱盐后,均得到分子量约43 kDa的可溶性纯化蛋白。酶促产物分析结果表明,两种酶催化产物均为白藜芦醇。酶动力学分析表明,虎杖STS催化效率(Kcat/Km)是葡萄STS的2.4倍。文中从植物类型Ⅲ聚酮化合物合酶(Polyketide synthase,PKS)超家族催化活性位点和保守位点角度分析了造成上述两种酶活性产生差异可能存在的原因。     

不同诱导子诱导虎杖愈伤组织白藜芦醇的生物合成

目的:研究不同胁迫条件对虎杖叶愈伤组织白藜芦醇含量的影响。方法:分别采用低温、热休克、紫外辐射、高盐、真菌诱激子、水杨酸(SA)、茉莉酸甲酯(MJ)处理虎杖叶愈伤组织,HPLC测定其中白藜芦醇的含量。结果:经过低温、紫外辐射、真菌诱激子、SA处理,白藜芦醇含量分别提高38%、20%、24%和18%(P<0.01),而热休克、NaCl高盐和MJ处理后,白藜芦醇含量与对照无显著差异(P>0.05)。结论:适当的胁迫条件能促进虎杖叶愈伤组织中白藜芦醇的合成。     

虎杖中白藜芦醇、白藜芦醇甙及大黄素的综合提取工艺研究

采用HPLC法,以白藜芦醇、白藜芦醇甙及大黄素的含量为指标,对虎杖中的有效成分进行了综合提取,通过正交实验,确定出乙醇溶剂提取的最佳工艺为：以80％的乙醇水溶液为提取剂,液固比为12：1,在70℃下提取2次,每次提取2h,HPLC法测定结果表明,从虎杖中提取的有效成分的含量分别可达：白藜芦醇为2．40mg／g,白藜芦醇甙为18．12mg／g,大黄素为16．82m/g。     

RP-HPLC法同时测定虎杖中白藜芦醇和白藜芦醇苷的含量

建立了国内首次用RP-HPLC同时测定虎杖中白藜芦醇和白藜芦醇苷含量的方法,并详细考察了2个指标成分的稳定性。对不同产地的虎杖药材、不同采收期的虎杖根及根茎以及虎杖的不同部位共25个样品中的白藜芦醇和白藜芦醇苷进行了含量测定,考察了两种活性成分的含量与产地、采收期及部位的关系,为虎杖资源的合理采收利用及进一步的研究提供了理论依据。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.