慈竹竹叶抗氧化活性成分的提取工艺研究

慈竹资源丰富,慈竹叶提取物为天然无毒的植物抗氧化剂。为有效地开发和利用慈竹叶资源,研究了慈竹叶抗氧化活性成分的提取工艺。通过单因素试验考察了提取溶剂乙醇浓度、样品粒度、提取方式、提取时间、料液比、提取温度、提取次数7个因素对慈竹竹叶抗氧化活性成分得率的影响。基于单因素试验结果,进一步运用L9(34)正交设计试验优化慈竹竹叶抗氧化活性成分的提取条件,并确定最佳提取工艺:20~28目竹叶粉末,70℃下,料液比为1∶10(g/m L),以60%乙醇静置提取1.5 h。验证试验确定此工艺稳定可行,可从1 g竹叶粉末中提取得到7.44 mg抗氧化活性成分。含量测定结果表明1 g竹叶粉末中含有总酚4.73 mg,总黄酮5.52mg。     

竹柏叶总黄酮不同提取方法比较

本研究采用正交试验设计分别优选回流提取和超声波提取竹柏叶总黄酮的最佳工艺条件。在单因素试验的基础上,以总黄酮得率为参考指标,选取液料比、乙醇体积分数、温度和时间4个影响因子,进行正交试验,分别确立回流提取和超声波提取最佳提取工艺条件。结果表明,回流提取优化工艺条件为:液料比30∶1(m L∶g),乙醇体积分数为70%,回流时间1.0 h,回流温度80℃;超声波提取优化工艺为:液料比25∶1(m L∶g),乙醇体积分数为70%,超声时间30 min,超声水浴温度60℃。两种提取方法的最终提取效果比较,回流提取的总黄酮得率为15.522%,超声波提取总黄酮得率为13.637%,回流提取法总黄酮得率高于超声波提取法。本实验结果为后续竹柏叶总黄酮的开发利用提供了参考。     

微波提取香水莲花总黄酮的工艺研究

该文研究了微波法提取香水莲花总黄酮的工艺。采用比色法测定黄酮的含量。利用单因素实验和正交实验考察了乙醇浓度、微波功率、微波时间、料液比对黄酮得率的影响,确定了最佳工艺为:用70%的乙醇溶液,微波功率250W,提取时间40 min,液料比25∶1,提取的总黄酮得率最高。     

正交设计优选橙皮苷提取工艺研究

采用碱-醇提酸沉法提取陈皮中橙皮苷,首先针对提取温度、提取时间、pH值、碱液料液比、醇液料液比、提取次数等因素对提取率的影响进行单因素实验考察,并进一步利用正交实验对橙皮苷的提取工艺进行优化。得到最优浸提条件为:陈皮粉与食用乙醇料液比为1:10、与0.5%NaOH溶液料液比1:10,浸提温度70℃,浸提时间4 h,提取率最高。     

超声波法提取荷叶多酚工艺研究

研究利用超声波辅助提取荷叶中多酚类化合物的最佳条件,考察了超声作用时间、提取次数、料液比和乙醇体积分数等因素对荷叶多酚提取率的影响,并在单因素实验的基础上进行正交实验,确定其优化工艺条件为:乙醇体积分数60%,作用时间15 m in,料液比为1:14,提取次数为4次。     

野西瓜低聚糖的提取及含量测定

目的:确定野西瓜低聚糖提取工艺参数并测定其含量.方法:对提取温度、提取时间、料液比和乙醇浓度进行了单因素和L9(34)正交试验;用分光光度法测定了野西瓜中低聚糖含量.结果:影响野西瓜低聚糖提取率的4个因素的影响程度依次为:提取时间>提取温度>乙醇浓度>料液比.最佳提取条件为:提取温度70℃、提取时间70min、料液比1/25、乙醇浓度80%,在此实验条件下低聚糖得率为3.70%.结论:实验结果为野西瓜低聚糖的进一步研究提供科学依据.     

超声波法提取短毛柽柳中总黄酮

目的：测定短毛柽柳中的总黄酮含量并确定其提取条件。方法：在提取过程中通过单因素实验分析了料液比、超声时间、乙醇浓度及超声温度等主要因素对提取率的影响。在此基础上通过正交设计法进行实验,优化短毛柽柳黄酮提取工艺条件。结果：短毛柽柳总黄酮的最佳提取工艺条件为料液比为1∶15,超声处理时间为40min,乙醇浓度为45%,超声温度50℃。根据实验测得的短毛柽柳总黄酮平均得率为33.675mg/g,含量为22.75%。结论：实验结果可靠、方法简便、省时且无污染,是提取短毛柽柳中黄酮化合物的有效途径。     

陇蜀杜鹃叶中金丝桃苷提取工艺研究

通过单因素和正交实验,提取陇蜀杜鹃叶中主要活性成分金丝桃苷,采用高效液相色谱法测定,确定金丝桃苷的最佳提取工艺。结果显示影响陇蜀杜鹃叶中金丝桃苷得率的主要因素是乙醇浓度,各因素影响顺序为乙醇浓度料液比提取温度提取时间,金丝桃苷最佳提取工艺为:乙醇浓度50%、料液比1∶25、提取温度80℃、提取时间1 h,得率为0.68%。该方法提取陇蜀杜鹃叶中的金丝桃苷得率高,稳定性好,工艺可控性强。     

诃子中总多酚含量的测定及其超声提取工艺的研究

目的：利用超声波辅助法提取诃子中总多酚。方法：考察了超声波的提取时间、乙醇浓度、料液比三个单因素对多酚提取率的影响,并在单因素实验基础上进行正交实验。结果：确立了诃子中总多酚的最佳工艺条件为：60%乙醇;料液比为1：20;超声提取60min。总多酚得率为13.27%。结论：此提取方法能够避免多酚在高温下的分解,极大地缩短了提取时间。     

锈毛莓总黄酮的提取工艺优化

采用乙醇回流提取法,对提取温度、乙醇浓度、时间、料液比进行单因素考察,结合正交试验,确定锈毛莓总黄酮最佳提取工艺。结果显示,最佳提取工艺为料液比1∶25、乙醇浓度60%、提取温度70 ℃、提取时间2.5 h,提取2次,总黄酮得率可达6.78%。     

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.     

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.     

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