硫脲壳聚糖Zn(Ⅱ)配合物的制备、表征及生物活性

利用FT-IR、UV、TG-DTA和XRD手段,对合成的硫脲壳聚糖及硫脲壳聚糖-Zn(Ⅱ)配合物进行了表征,研究了壳聚糖、硫脲壳聚糖及硫脲壳聚糖-Zn(Ⅱ)配合物对细菌大肠杆菌、金黄色葡萄球菌和真菌黑曲霉的抑菌性能.结果表明:合成的硫脲壳聚糖-Zn(Ⅱ)配合物对大肠杆菌、金黄色葡萄球菌的抑菌性能比单一的壳聚糖、硫脲壳聚糖显著提高,对真菌黑曲霉亦具有较强的抑制作用.     

几种天然产物的抑菌性能研究

将羧甲基壳聚糖等四种天然产物作为供试样,分别测定其对大肠杆菌、金黄色葡萄球菌、绿脓杆菌、枯草杆菌的最低抑菌浓度,结果表明,四种供试样对其均有一定的抑制作用,其中壳寡糖对大肠杆菌、金黄色葡萄球菌、枯草杆菌的抑制作用最强,羧甲基壳聚糖、壳寡糖、白芨多糖对绿脓杆菌的抑制能力差不多。再根据单体实验结果,选择羧甲基壳聚糖、壳寡糖、白芨多糖进行两两复配实验,结果表明,壳寡糖与白芨多糖的复配液对于金黄色葡萄球菌、枯草杆菌有较明显的协同增效抑菌作用。     

低聚壳聚糖美拉德衍生物抑菌性能研究

本文研究了基于与葡萄糖、麦芽糖和木糖进行美拉德反应的低聚壳聚糖衍生物的抑菌性.测定低聚壳聚糖及其衍生物对大肠杆菌和金黄色葡萄球菌的抑制效果.结果显示:壳聚糖及其衍生物对金黄色葡萄球菌的抑制作用强于对大肠杆菌的抑制作用,且随着浓度增加,对两种菌的抑菌效果增强.大多数壳聚糖衍生物的抑菌效果优于壳聚糖本身,其中CG 1∶1 8 h(低聚壳聚糖的氨基与葡萄糖的羰基的物质量比为1∶1,反应8h)的抑菌效果最好,CM 1∶3 8 h(低聚壳聚糖的氨基与麦芽糖的羰基的物质量比为1∶3,反应8 h)抑菌性最差,这可能与参加反应的还原糖种类、反应物比例以及反应时间相关.     

抗菌脂肽制备羧甲基壳聚糖纳米粒稳定混悬液及其抑菌活性

利用抗菌脂肽解决羧甲基壳聚糖纳米粒制备过程中出现的团聚问题,并考察其对羧甲基壳聚糖纳米粒的抑菌效果影响.通过抗菌脂肽乳化分散离子交联法制备羧甲基壳聚糖纳米粒,静置观察其稳定性,乌氏粘度计测定其粘度变化,扫描电镜考察其形态改变,比浊法测定不同浓度纳米粒溶液对金黄色葡萄球菌和大肠埃希菌的抑制作用.实验发现,加入抗菌脂肽制备的纳米粒稳定性好,粘度降低,形态均一,并能显著增强对金黄色葡萄球菌和大肠埃希菌的抑制作用.结果表明,抗菌脂肽的加入能很好的解决纳米粒制备过程中出现的团聚现象,而且其抑菌效果也有很大改善.     

11种食药同源植物提取物对果蔬常见腐败菌的抑菌活性研究

本文以花椒、高良姜等11种食药同源植物提取物为供试材料,分别研究了其对扩展青霉、灰葡萄孢、链格孢和大肠杆菌、金黄色葡萄球菌等5种常见果蔬腐败菌的抑制作用。结果表明,花椒对三种霉菌抑制作用最强,高良姜和莱菔子对扩展青霉和链格孢有一定抑制作用。花椒对三种霉菌的最小抑菌浓度分别为25. 00、25. 00、50. 00 mg/m L,最小杀菌浓度分别为50. 00、100. 00、100. 00 mg/m L。花椒对三种霉菌的孢子萌发有显著抑制作用。花椒提取液处理樱桃番茄可显著降低果实发病率,延长果实保鲜期。11种食药同源植物提取液对大肠杆菌抑菌效果较差。高良姜和天麻对金黄色葡萄球菌抑菌效果突出,可显著抑制金黄色葡萄球菌生长,二者对金黄色葡萄球菌的MIC分别为7. 50和30. 00 mg/m L,MBC分别为15. 00和60. 00 mg/m L。     

添加壳聚糖的藻酸盐印模材料抗菌性能研究

目的:对添加壳聚糖的藻酸盐印模材料的抗菌性进行测试,为口腔抗茵印模材的研究奠定基础.方法:分别以不同的添加比将不同分子量和脱乙酰度的壳聚糖加入藻酸盐印模材料中,采用薄膜密着法分别测试添加抗菌成分后印模材料对大肠杆菌,金黄色葡萄球菌的抗茵活性.结果:壳聚糖分别以1%和1.4%的添加比添加到藻酸盐印模材料中,对大肠杆菌和金黄色葡萄球菌有最好的抗菌性.随着脱乙酰度的提高,抑菌率均可达到100%.结论:添加壳聚糖的藻酸盐印模材料具有良好的抗茵效果.     

壳聚糖中胺基对其抑菌性能的影响及与DNA的作用

采用抑菌圈法研究了壳聚糖对大肠杆菌(E.coli)和金黄色葡萄球菌(St.aureus)的抑菌活性。利用壳聚糖的席夫碱反应,对壳聚糖的胺基进行保护后,研究了壳聚糖中胺基对其抑菌性能的影响。同时,运用紫外吸收光谱和电化学的方法,研究了壳聚糖与DNA的相互作用,提出了壳聚糖对E.coli和St.aureus的抑菌机理。研究结果表明,壳聚糖对E.coli和St.aureus具有很好的抑制作用,且抑菌活性与其胺基有关;壳聚糖能与细胞内带负电的核酸结合,使细胞正常DNA复制生理功能受到影响,抑制细菌的繁殖,从而达到抑菌的目的。     

壳聚糖微球分散体系的抑菌性研究

以乳化交联法制备的壳聚糖微米微球(CMs)为试验材料,研究其对金黄色葡萄球菌和大肠杆菌的抑菌行为,并对其浓度因素、粒径因素和抑菌机理做了探讨。结果表明CMs的抑菌作用随其浓度的增加和粒径的减小而增强。在浓度<0.7 mg/mL时,CMs对细菌的生长具有先抑制后促进的作用;当浓度≥0.7 mg/mL时对细菌有杀灭作用。CMs对两种细菌的最小抑菌浓度和最小杀菌浓度分别为0.8、1.4 mg/mL和1.0、1.8 mg/mL,表明壳聚糖微球对金黄色葡萄球菌和大肠杆菌均具有明显的抑制作用,且金黄色葡萄球菌对微球抑制作用的反应比大肠杆菌更敏感。扫描电子显微镜观察发现,细菌能迅速贴附在CMs表面,并且贴壁后的细菌发生了明显的形态变化,有的甚至完全被破坏。     

十八种辛香料对五种食源性致病菌的抑菌研究(英文)

本实验研究18种辛香料对五种食源性病原菌:单增李斯特菌,大肠杆菌O157∶H7,肠炎沙门氏菌,副溶血性弧菌和金黄色葡萄球菌的抑制作用。辛香料以60℃蒸馏水浸提。研究各种辛香料的最低抑菌浓度(80~5 mg/mL)以及经100℃处理15 m in和121℃处理15 m in的稳定性。结果表明,大部分辛香料具有良好的抑菌效果,尤其是丁香和桂皮对副溶血弧菌和金黄色葡萄球菌的最低抑菌浓度为5 mg/mL。经热处理部分香料失去了抑制作用,如八角,茴香,五香粉,海南白和黑胡椒,但大多数香料保持抑菌效果。这些结果表明,香料可抑制感染海产品的病原菌,同时在加工香料的过程中应该避免高温处理。     

苦瓜总皂甙对金黄色葡萄球菌抑制作用的研究

研究苦瓜总皂甙的抑菌作用及抑菌条件。以苦瓜正丁醇浸提物为原料,研究其对金黄色葡萄球菌的抑菌作用。试验结果表明,苦瓜总皂甙对金黄色葡萄球菌的抑制作用明显,最低抑菌浓度为30 mg/mL;抑菌最适pH值范围5~8;苦瓜总皂甙的热稳定性好,在121℃处理10 min仍具有较好的抑菌活性。金黄色葡萄球菌生长曲线表明,对数生长期的金黄色葡萄球菌对苦瓜总皂甙较敏感,而对接近稳定期的菌体抑制作用较弱。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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.     

Synthesis and antimicrobial studies of hydrazone derivatives of 4-[3-(2,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid and 4-[3-(3,4-difluorophenyl)-4-formyl-1H-pyrazol-1-yl]benzoic acid

Microbial resistance to antibiotics is an unresolved global concern, which needs urgent and coordinated action. One of the guidelines of the Centers for Disease Control and Preventions (CDC) to combat antibiotic resistance is the development of new antibiotics to treat drug-resistant bacteria. In our effort to find new antibiotics, we report the synthesis and antimicrobial studies of 30 new pyrazole derivatives. These novel molecules have been synthesized by using readily available starting materials and benign reaction conditions. Some of these molecules have shown activity with MIC values as low as 0.78?µg/mL against four bacterial strains; Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, and Acinetobacter baumannii. Furthermore, active molecules are non-toxic to mammalian cell line.

     

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.     

Novel compounds with potent CDK9 inhibitory activity for the treatment of myeloma

Cyclin-dependent kinases (CDKs) and Polo-like kinases (PLKs) play key role in the regulation of the cell cycle. The aim of our study was originally the further development of our recently discovered polo-like kinase 1 (PLK1) inhibitors. A series of new 2,4-disubstituted pyrimidine derivatives were synthesized around the original hit, but their PLK1 inhibitory activity was very poor. However the novel compounds showed nanomolar CDK9 inhibitory activity and very good antiproliferative effect on multiple myeloma cell lines (RPMI-8226).