土茯苓中总黄酮的含量测定方法研究

目的：建立土茯苓总黄酮的含量测定方法。方法：采用70%乙醇超声提取工艺和可见分光光度法测定土茯苓中总黄酮的含量,以芦丁为对照品,在500 nm波长处测量。结果：芦丁在0.008～0.048 mg.mL-1范围内线性关系良好（r=1.000）,平均加样回收率（n=6）以芦丁计为98.34%,RSD为3.4%。结论：此方法操作简单,精密度、稳定性和重复性良好,可用于土茯苓总黄酮含量测定。     

水龙骨中总黄酮的含量分析

目的:对水龙骨中总黄酮含量进行测定,为水龙骨质量评价提供依据.方法:芦丁-UV方法进行测定.结果:总黄酮在0.001 68～0.067 2 mg/mL范围有良好的线性关系(r=0.999 1),加样回收率为98.23%,RSD=3.52%.结论:该法样品处理简单、迅速,可以做为水龙骨中总黄酮的含量测定方法.     

广西不同产地番石榴叶总黄酮含量测定

目的对广西不同产地番石榴叶中总黄酮含量进行测定。方法应用紫外分光光度法,以芦丁为对照品,于357nm下测定吸光度,计算番石榴叶中总黄酮的含量。结果在1.7~14.3范围内总黄酮含量与吸光度A值线性关系良好,平均回收率=99.28%,RSD=3.69%,R2=0.9993。结论该方法简便可靠、快速、重现性好,适用于番石榴叶总黄酮含量测定。采收地区不同,番石榴叶中总黄酮的含量也不同。     

日本旋覆花总黄酮的微波提取与含量测定

目的:探讨提取日本旋覆花总黄酮的方法并对其含量进行分析.方法:采用微波技术提取日本旋覆花中的总黄酮,同时以芦丁为对照品,用分光光度法测定不同产地日本旋覆花的总黄酮含量.结果:日本旋覆花总黄酮在10.4～51.7μg/ml范围内线性关系良好,回归方程为:Y=12.1841X+0.0003 (r=0.9999,n=5),方法回收率为99.2％,RSD为1.49％.结论:微波提取技术操作简单,效果可靠,适用于日本旋覆花总黄酮的提取.     

以沙苑子苷为对照品测定沙苑子总黄酮含量

目的 :以沙苑子苷为对照品测定沙苑子总黄酮含量。方法 :80 %乙醇提取液 ,2 6 6nm测定紫外吸收度。结果 :总黄酮含量为 2 1.5mg/g ,RSD =1.0 0 % ;回收率 95 .4 % ,RSD =2 .2 7% ,线性范围 4～ 2 4ug/ml。结论 :本法测定沙苑子总黄酮含量 ,操作简便 ,稳定性好 ,可用于沙苑子的质量控制。     

不同部位艾纳香中总黄酮的含量测定

以芦丁为对照品,建立紫外分光光度法检测艾纳香总黄酮含量的方法,并检测艾纳香中不同部位总黄酮的含量。结果表明:芦丁在0~0.04832mg/mL(r=0.9998)范围内线性关系良好,平均回收率为99·7%,RSD=2.3%,其叶、小枝条、茎含总黄酮分别为2.94%,1.21%,1.36%,该方法简便、可靠、准确,结果可作为艾纳香中总黄酮含量的检测方法。     

荧光光度法测定萹蓄中总黄酮含量

目的:建立一种准确测定萹蓄中总黄酮含量的新方法.方法:以芦丁为标准样品,用荧光分光度法测得其荧光强度、绘制标准曲线.用60%乙醇加热回流提取萹蓄有效成分,在相同的条件下测定样品中总黄酮的荧光强度,根据回归方程求得其含量.结果:当芦丁的浓度范围在0μg/mL～22μg/mL时,荧光强度和芦丁浓度具有良好的线性关系,线性回归方程Y=-8.973X 22.581,相关系数r=0.9771.篇蓄中总黄酮的平均含量17.05μg/mL,所得率为6.82%.结论:用荧光分光度法测定萹蓄中总黄酮的含量,操作简便、快速、准确,建议推广应用.     

核桃仁内隔膜中总黄酮最佳提取工艺的研究

目的:从核桃仁内隔膜中提取并测定总黄酮含量,选择最佳提取工艺条件.方法:以芦丁为对照品,用分光光度法在最大吸收波长510nm对其含量进行测定.结果:测得样品中总黄酮含量C=6.430%,最佳提取工艺:乙醇浓度为75%、料液比为1:40、超声提取时间为60min、超声提取温度为80℃.结论:选用芦丁为对照品应用于紫外分光光度法测定核桃仁内隔膜总黄酮含量准确度较高,方法简单,可作为测定核桃仁内隔膜中黄酮含量的一种手段.     

白补药总黄酮含量测定方法的建立

以贵州省黔东南州雷公山白补药为研究对象,采用NaNO_2-Al(NO_3)_3-NaOH协同显色体系,紫外分光光度法测定白补药中总黄酮含量。对显色剂的用量及显色时间进行了研究。研究结果表明:以0.5 m L 5%NaNO_2(放置6 min)、0.5 m L 10%Al(NO_3)_3(放置6 min)和5 mL 4%NaOH(放置15 min)为最佳显色体系,芦丁为标准品,在505 nm波长下进行测定,标准品在10-62μg/m L范围内与吸光度呈现良好的线性关系,加标回收率为99.2%,RSD=1.2%,其回归方程和相关系数分别为y=11.0767x+0.0071,r=0.9991。该方法具有重现性好,可操作性强等优点。可以用于白补药中总黄酮含量的测定。     

四种绿绒蒿属植物中总黄酮含量测定

本文采用比色法测定了4种绿绒蒿属植物中总黄酮的含量,该方法线性关系良好(r2=0.9990),平均回收率为101.56%,精密度和重复性试验RSD分别为2.94%和1.22%,表明本试验的重复性较好。结果显示总黄酮含量以五脉绿绒蒿中最高,全缘和红花绿绒蒿次之,总状绿绒蒿中最低,4种药材总黄酮含量的变化与其用途差异基本吻合,与藏医用药品次习惯较为相符。本实验结果可以为绿绒蒿属药用植物资源的深入研究和开发利用提供一定的理论依据。     

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