化学衍生-溶剂结晶法从植物甾醇混合组分中分离豆甾醇

采用化学衍生和溶剂结晶法,建立起一条从植物甾醇混合组分分离豆甾醇的技术途径。通过对植物甾醇的乙酰化,溴化-脱溴和皂化反应,并结合相应试样的重结晶操作以分离豆甾醇。利用此方法从植物甾醇混合组分分离豆甾醇,其产率为6.9%,回收率45.7%,具有生物工业应用潜力。     

微波辐射一步法合成香料富马酸二苄酯的研究

目的:在微波辐射下,以顺丁烯二酸酐和苄醇为原料,在复合催化剂对甲苯磺酸-硫脲存在下以甲苯为带水剂一步合成了富马酸二苄酯.方法:通过熔点测定和红外光谱分析对产物进行了结构表征.采用正交试验法研究了反应物的摩尔比、催化剂用量、反应温度、辐射反应时间等对产物收率的影响.结果:实验结果表明,在微波功率为700W,n(顺丁烯二酸酸酐):n(苄醇)=1:5,复合催化剂用量为总投料量的7%,甲苯20mL,一酯化、转化、二酯化的温度分别为140℃、145℃、135℃,回流分水90min的条件下,富马酸二苄酯的收率可达92.50%.结论:采用微波辐射法复合催化合成富马酸二苄酯具有操作简便、反应时间短、产物收率高等特点.     

β-谷甾醇烟酸酯的制备

采用酯化反应,将烟酰氯和β-谷甾醇合成了β-谷甾醇烟酸酯,并用红外光谱和质谱对其进行了分析。结果表明,酯化反应的最优工艺条件为mol(β-甾醇):mol(烟酰氯):mol(吡啶)= 1:3:5;反应温度91℃;反应时间6 h;用95%的乙醇进行重结晶,产率可达到75%以上;红外光谱和质谱分析表明合成产物为β-谷甾醇烟酸酯。     

酶法合成糖及糖醇酯

以脂肪酸为酰基供体,糖和糖醇为酰基受体,利用吸附到涤棉布上的假丝酵母脂肪酶作催化剂,在含叔丁醇的系统中,研究了酯化反应条件。酯化最适温度和pH值分别为40℃～45℃和50～75。在酰基供体中,以亚油酸和油酸最好,C8到C22的饱和脂肪酸的酯化程度相仿。在23种糖和糖醇中,果糖、木糖、海藻糖、山梨糖、木糖醇、甘露醇以及异丙基葡萄糖和甲基葡萄糖比其它酰基受体的酯化率高。糖醇的酯化程度明显高于相应的糖。此外,酰基供体与受体的摩尔比大于2∶1时,有利于酯化。在由30mmol(085g)油酸,02mmol山梨醇(0036g),3mL叔丁醇和30mg固定化酯肪酶(600u)组成的反应系统中,40℃震荡反应48h,以等摩尔的底物计算,酯化程度达到90%以上。反应产物经薄层色谱鉴定为单酯和双酯。     

超声辅助酶促合成丙二酸单对硝基苄酯

为了研究超声对固定化脂肪酶Novozym 435催化合成丙二酸单对硝基苄酯反应的影响。对超声辅助酶促酯化反应条件进行了优化,确定最佳反应条件:以甲苯为溶剂,固定化脂肪酶Novozym 435质量浓度为3.0 g/L,对硝基苄醇质量浓度为4.0 g/L,反应温度为30℃,反应时间为5 h,超声声强为0.8 W/cm2,超声频率为20 k Hz,丙二酸单对硝基苄酯收率为89.7%。与振荡水浴条件相比,超声辅助酶催化反应能强化传质,在反应温度降低15℃,时间缩短3 h和固定化酶浓度减少1.5 g/L的同时,产物收率增加了18.2%。超声作用下,Novozym 435重复使用性能较佳,应用于酯化反应8次后,丙二酸单对硝基苄酯收率为69.3%。     

程序降温法固相酶催化棕榈油甘油解的研究

单脂肪酸甘油酯(单甘酯)的酶法合成工艺中最具有工业化前景的当属固体相油脂甘油解。彭立风、谭天伟[1～2]以猪胰脂肪酶固相催化牛油、棕榈油甘油解合成单甘酯,甘油与油脂摩尔比为2～4∶1,最佳反应温度下反应24ｈ后单甘酯含量最高分别达1951%和2417%,将反应物于更低温度下…     

非水溶剂中Rhizopus arrhizus脂肪酶催化合成三种酯的最佳条件(英文)

以少根根霉 (Rhizopusarrhizus)脂肪酶为催化剂 ,有机溶剂为反应介质 ,合成了 3种短链脂肪酸酯 .研究了反应温度、溶剂、底物浓度、底物摩尔比、吸水剂用量等因素对酯化反应的影响 .确定了3种酯的最佳合成条件 :(1)己酸乙酯 :反应温度为 4 0℃ ,环己烷为溶剂 ,0 2 5mol L底物浓度 ,酸醇摩尔比为 1∶1 2 ;(2 )乙酸异丙酯 :5 0℃ ,环己烷为溶剂 ,0 15mol L底物浓度 ,摩尔比为 1∶1;(3)乙酸异戊酯 :5 0℃ ,异辛烷为溶剂 ,0 2 0mol L底物浓度 ,摩尔比为 1∶1.三种酯合成时均需 0 12 5g ml的0 5nm分子筛为吸水剂 ,在 8h后 ,合成酯转化率达到 97%～ 99% .     

邻甲苯甲酸催化合成邻甲苯腈的研究

采用连续流动塔式气固催化法合成邻甲苯腈,通过正交实验得出最佳反应条件为:反应温度270℃,反应物摩尔比n_(邻甲苯甲酸):n_(氨气)=1:1.6。由于主要反应物为固体,在实验室采取间歇投料小规模实验,单次投料量为5g(投料间隔时间为30min),最高的摩尔产率为99.3%。     

双氧水介导制备对硝基苯甲酸乙酯的初步研究（英文）

目的：探讨双氧水催化合成对硝基苯甲酸乙酯的可行性,并考察了反应物的摩尔比、催化剂用量、反应温度及反应时间对产物收率的影响。方法：分别采用单因素设计实验与正交设计实验,分析比较这两种方法的最佳反应条件。采用数字熔点仪测定样品的熔点;用GC112A型气相色谱仪测定了产物的纯度;用傅里叶变换红外光谱仪测定产物的结构。结果：双氧水可以作为合成对硝基苯甲酸乙酯的催化剂。综合分析可知：当无水乙醇和对硝基苯甲酸的摩尔比为4：1,催化剂含量为10%,反应温度为80℃,反应时间为2.5-3h时酯化产率可达到最高值。结论：双氧水催化对硝基苯甲酸、无水乙醇合成对硝基苯甲酸乙酯的效率较高,产品纯度高,环境污染小,不失为一种新的合成方法。     

双氧水介导制备对硝基苯甲酸乙酯的初步研究

目的:探讨双氧水催化合成对硝基苯甲酸乙酯的可行性,并考察了反应物的摩尔比、催化剂用量、反应温度及反应时间对产物收率的影响.方法:分别采用单因素设计实验与正交设计实验,分析比较这两种方法的最佳反应条件.采用数字熔点仪测定样品的熔点:用GC112A型气相色谱仪测定了产物的纯度;用傅里叶变换红外光谱仪测定产物的结构.结果:双氧水可以作为合成对硝基苯甲酸乙酯的催化剂.综合分析可知:当无水乙醇和对硝基苯甲酸的摩尔比为4:1,催化剂含量为10%,反应温度为80℃,反应时间为2.5-3h时酯化产率可达到最高值.结论:双氧水催化对硝基苯甲酸、无水乙醇合成对硝基苯甲酸乙酯的效率较高,产品纯度高,环境污染小,不失为一种新的合成方法.     

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.     

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.     

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.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

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).     

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.