土茯苓中提取总黄酮的工艺研究

采用乙醇溶液提取土茯苓饮片中总黄酮,分析了乙醇浓度、温度、固液比、浸取时间对总黄酮提取率的影响。进行了单因素实验设计,得出优化实验条件：乙醇浓度50%,浸取温度80℃,固液比1:20,浸取时间3h,总黄酮提取率为75.8%。     

微波提取山楂中黄酮类化合物的工艺优化

以总黄酮得率为指标,采用微波法辅助提取山楂叶中的总黄酮,选取浸提时间、乙醇体积分数、微波辐射时间、液固比等参数进行单因素试验,选择影响较大的因素,利用Design-Expert 8.0.5b进行响应面分析,得到优化的提取工艺条件:乙醇体积分数56%,液固比51 m L/g,微波辐射时间3.7 min,在此条件下,山楂叶中总黄酮得率为8.923%。     

响应面法优化合萌总黄酮提取工艺

目的:利用响应面法优化合萌中总黄酮的提取工艺条件。方法:通过单因素试验分别考察提取时间、乙醇体积分数、液固比、提取温度及提取次数对合萌总黄酮得率的影响,并选取提取时间、乙醇体积分数、液固比、提取温度为影响因子,应用响应面法优化提取工艺。结果:合萌总黄酮的最佳提取条件为:提取时间60 min,乙醇浓度65%,液固比(g∶m L)25∶1,提取温度90℃,在此条件下,合萌总黄酮得率为4.08 mg/g,接近模型预测值4.11 mg/g。结论:响应面法在一定程度上可以提高合萌总黄酮得率,表明响应面法用于合萌总黄酮提取工艺的优化具有可行性。     

响应面法优化细果角茴香中总黄酮的超声提取条件

采用响应面法优化超声波辅助提取细果角茴香中总黄酮的工艺研究。在单因素试验的基础上,选择超声时间、乙醇浓度、料液比为自变量,以总黄酮的提取率为响应值,进行Box-Behnken中心组合实验设计,采用响应面法(RSM)评估了这些因素对总黄酮提取率的影响。结果表明:超声波法辅助提取细果角茴香中总黄酮的最佳工艺条件为液料比33 mL/g,乙醇浓度为58%,提取时间为34.5 min。在此条件下,总黄酮的提取率达1.525%。     

余甘子总黄酮超声波辅助提取工艺的优化

以余甘子干粉为材料,利用超声波辅助提取余甘子总黄酮。单因素试验分析液料比、乙醇浓度、超声时间、超声功率对余甘子总黄酮提取率的影响,在此基础上,利用响应面分析法对提取工艺进行优化。结果表明,余甘子总黄酮最佳提取条件为：液料比82:1(V/W)、乙醇浓度45%、超声时间41 min、超声功率210 W,在此条件下余甘子总黄酮的实际提取率为6.12%。     

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。     

响应面法优化蕤核叶片总黄酮提取工艺

采用超声波辅助提取的方法从蕤核叶片中提取总黄酮.利用响应面法(RSM法)研究了超声提取时间、乙醇浓度、液固比、提取温度等因素对总黄酮得率的影响,确定了超声波辅助提取蕤核叶片总黄酮的最佳工艺参数.结果表明,超声波辅助提取蕤核叶片总黄酮的最佳工艺务件为:超声时间50.1 min,乙醇浓度59.5%,液料比24.9:1,提取...     

响应面法优化益母草总黄酮的提取工艺研究

采用响应面法优化超声提取益母草总黄酮的工艺条件。方法:在超声时间、超声功率、超声温度、料液比等单因素的基础上,通过中心组合设计原理采用三因子三水平的响应面分析法设计,对单因子显著性和交互作用进行分析。结果:超声提取益母草总黄酮的最佳工艺条件为:超声时间35.54 min,料液比1∶30.63,乙醇浓度73.41%。此时吸光度为0.295 9。在此条件下益母草的总黄酮提取率为1.21%。结论:优化的提取工艺条件,益母草的总黄酮提取率高,节约资源。     

响应面法优化提取宽叶独行菜总黄酮工艺研究

研究了乙醇浓度、提取温度、提取时间、液料比对超声辅助提取宽叶独行菜总黄酮提取率的影响。采用Box-Bohnken试验响应面分析法优化提取工艺。结果表明最佳提取条件:乙醇浓度75%,提取时间89 min,液料比22.5 mL/g,提取温度79℃,所得的总黄酮提取量为36.5 mg/g。本试验为更好的开发利用宽叶独行菜资源提供一定科学依据。     

响应面法优化微波法提取荷叶中总黄酮的研究

采用微波提取法对荷叶总黄酮进行提取,通过响应面试验分析确定最佳的荷叶总黄酮的最佳提取工艺:微波功率346.57W,微波时间1.04min,料液比1:28.21,乙醇浓度69.65%,理论提取率为5.02%。经3次平行试验的实际平均提取率为4.98%。     

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     

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.     

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