利用精氨酸和缬氨酸设计新型α-螺旋抗菌肽

摘要：【目的】抗菌肽是生命体的自身免疫系统的重要组成部分。其中两性的α-螺旋抗菌肽在抗菌肽家族中又占有重要的地位,发挥着重要的作用。为了得到具有更高抗菌活性同时具有很低细胞毒性的抗菌肽,根据α-螺旋二级结构衍生出来的螺旋轮模型,设计了一条在疏水一侧含有8个缬氨酸和亲水一侧含有5个精氨酸的新型16残基抗菌肽。【方法】测定了设计得到的新型抗菌肽的最小抑菌浓度、对于红细胞和哺乳动物肾细胞的细胞毒性以及杀菌动力学。 【结果】抗菌活性检测表明,新型抗菌肽VGR16显示了强并快速的杀菌作用,其最小抑菌浓度在16－64     

重组人β防御素-3抗菌活性及其影响因素研究

采用琼脂扩散法对重组人β防御素-3(rhβD-3)的抗菌谱、最小抑菌浓度及其抗菌活性影响因素进行研究。结果表明,rhβD-3对G~+、G~-及真菌均有抑制作用。rhβD-3对金黄色葡萄球菌的最小抑菌浓度为15μg/mL,对大肠杆菌的最小抑菌浓度为20μg/mL。对rhβD-3的抗菌活性影响因素进行测定,结果表明rhβD-3在pH6.0时抗菌活性最高;而且在-70℃~100℃条件下仍具有较高的抗菌活性;在高于100 mmol/L NaCl浓度下,抗菌活性随着NaCl浓度的升高而降低。     

余甘子不同溶剂提取物抗炎活性的研究

本试验旨在筛选出余甘子不同溶剂提取物的最佳抗炎活性部位。试验以水、乙醇、乙酸乙酯和石油醚为提取溶剂得到余甘子不同溶剂提取物(水提取物分成三个组分:水(1)组分分子量小于6000;水(2)组分分子量在6000到10000之间;水(3)组分分子量大于10000),采用LPS诱导RAW264.7巨噬细胞建立炎症模型;以NO分泌量和细胞因子(TNF-α、IL-1β、IL-6)释放量为指标,筛选出余甘子不同溶剂提取物最佳抗炎活性部位。余甘子不同溶剂提取物在浓度25~400μg/m L之间对细胞无明显细胞毒性(P0.05)。与模型组相比,水(1)、水(2)和乙醇提取物能显著抑制LPS诱导巨噬细胞分泌NO(P0.05)。在细胞因子实验中,乙醇提取物极显著抑制LPS诱导RAW264.7巨噬细胞分泌IL-1β和TNF-α(P0.01);乙酸乙酯提取物抑制LPS诱导RAW264.7巨噬细胞分泌IL-6的效果最佳。综合评价得出余甘子乙醇提取物作为筛选出的最佳抗炎活性部位,其极显著抑制LPS诱导RAW264.7巨噬细胞分泌NO和细胞因子(TNF-α、IL-1β、IL-6),可以作为后续分离鉴定抗炎活性物质单体的活性部位。     

糙苏提取物抑菌活性的初步评价

目的:比较糙苏甲醇提取物和丙酮提取物的抗菌活性.方法:对糙苏的丙酮提取物和甲醇提取物进行体外抗菌活性实验,测定其最小抑菌浓度(MIC)和最小杀菌浓度(MBC),比较相应的MIC和MBC值.结果:两种提取物对所选取的8种菌株均具有抑菌效果,丙酮提取物的抑菌活性高于甲醇提取物.巨大芽孢杆菌是对提取物最敏感的细菌.结论:糙苏提取物作为天然抗菌物质,具有广谱抗菌效果,具有较高的应用潜力和综合开发前景.     

金樱子多糖的抑菌和抗炎作用研究

研究了金樱子多糖的抗菌活性和抗炎作用。实验表明:金樱子多糖具有一定的抑菌活性,如对大肠杆菌、副伤寒杆菌、白葡萄球菌以及金黄色葡萄球菌等均有较强的抑制作用;能抑制二甲苯引起小鼠的耳肿胀,与NS组比较有明显差异(P<0.01),具有一定的抗炎作用。     

合成多肽对结核分枝杆菌的胞内抑制作用

评价合成多肽对人白血病单核巨噬细胞THP-1的毒性和对结核分枝杆菌H37Rv的胞内抑菌作用。通过多肽的不同给药浓度,确定多肽对结核分枝杆菌的最小抑菌浓度(MIC),利用流式细胞术方法和MTT法检测2号肽对细胞THP-1的毒性作用,同时采用CFU方法检测其对H37Rv菌株的胞内抑菌作用。筛选的4条多肽均有抑菌作用,其中2号肽的最小抑菌浓度(MIC)最小,为200μg/m L。2号肽与细胞THP-1作用时,浓度为1 200μg/m L时表现出细胞毒性,与INH细胞毒性无显著差别。对于胞内H37Rv,2号肽抗结核作用具有时间和剂量依赖效应,随给药时间和剂量的增加H37Rv菌落数明显下降。2号肽不仅对巨噬细胞THP-1的毒性小,而且具有较好的抗胞内结核分枝杆菌活性,是一种潜在的抗结核新型药物。     

基于PI3K/AKT/mTOR通路的三百棒促进脂多糖诱导的RAW 264.7细胞自噬并抑制炎症CSCD

三百棒来源于芸香科植物飞龙掌血Toddalia asiatica(L.)Lam的根,是一种天然土家族中草药,具有抗炎、抗风湿、抗肿瘤、抗微生物等药理活性。其毒副作用小,疗效显著的特点使之成为当前研究热点。许多天然产物已被证明可通过靶向PI3K/AKT/mTOR介导的自噬来抑制炎症及自身免疫性疾病,本项研究通过调节PI3K/AKT/mTOR信号通路来研究三百棒醇提物(Toddalia asiatica alcohol extract,TAAE)对自噬的影响,用脂多糖(LPS)诱导单核巨噬细胞(RAW 264.7)建立炎症模型,通过细胞毒性检测试剂盒检测TAAE对细胞活力的影响,并筛选出药物的浓度及干预时间,透射电镜和单丹磺酰尸胺染色检测巨噬细胞的生物学功能,酶联免疫吸附法检测上清液中相关炎症因子水平,Western blot检测自噬和通路相关蛋白的表达水平;并采用自噬早期抑制剂(3-MA)和通路PI3K激动剂(740Y-P)进一步验证自噬对炎症和信号通路的影响。实验结果表明TAAE可能通过抑制PI3K/AKT/mTOR信号通路,促进自噬泡的形成、自噬体溶酶体融合和降解,降低LPS处理的RAW 264.7细胞中炎性细胞因子的表达和分泌。总体而言,本研究结果为三百棒的抗炎机制的研究提供了新的线索,并为临床更好的应用三百棒治疗炎症性疾病提供理论依据。     

生物抗菌多肽在换牙期儿童专用牙膏中的应用

目的:由于换牙期儿童牙齿及口腔的独特特点(疼痛、易出血、有炎症、易引起发烧),故迫切需要一款专用牙膏。研究了本公司研制的新型生物牙膏中的活性多肽对口腔微生物的抗菌作用。方法:测定生物抗菌多肽(包括:MSI-1,BF-30,Cbf-14,Cbf-K_(16))对口腔微生物的最小抑菌浓度(Minimal inhibitory concentration,MIC),最小杀菌浓度(Minimal bactericide concentration,MBC)及杀菌曲线(Killing curves,KCs),同时评估抗菌多肽牙膏对平板培养微生物的抑菌效果强弱,分析其对口腔微生物的作用。结果:几种多肽对三种细菌均具有良好的杀菌活性,MIC范围为4-32μg/ml,且都能在4 h之内杀灭所有细菌,同时生物活性多肽复合物对微生物也有明显的抑制效果。结论:生物抗菌多肽牙膏中的几种活性多肽具有广谱的杀菌作用,具有潜在的实用价值和临床指导意义。     

超声微波协同提取小米糠总黄酮工艺及其抗炎活性研究

对小米糠总黄酮的超声微波协同提取工艺和抗炎活性进行研究。在单因素试验基础上,采用Box-Behnken方法设计多因素试验,研究超声微波时间、乙醇浓度、料液比、微波功率对小米糠总黄酮提取量的影响,建立试验工艺参数与提取量之间的数学模型,确立最佳提取工艺,并对其进行光谱表征;并通过小米糠总黄酮对脂多糖(LPS)诱炎症RAW264.7巨噬细胞的增殖及促炎性细胞因子试验,测定其抗炎活性。超声微波协同萃取小米糠总黄酮的最佳工艺参数为:超声微波时间为0.87 h,乙醇浓度为77%,料液比为1∶19 g/m L,微波功率为486 W,此时提取量为31.26 mg/g,较传统的乙醇回流法提高205%;结果表明小米糠总黄酮结构与芦丁基本一致;小米糠总黄酮浓度在50~200μg/m L范围内,可以明显降低LPS对巨噬细胞增殖的抑制作用、修复细胞形态及显著下调胞内促炎性因子的分泌,并且呈剂量依赖性关系。这表明小米糠总黄酮具有一定的抗炎效果,是一种潜在的免疫调节剂。     

香椿嫩芽和老叶萃取物抗菌活性的比较研究

采用琼脂扩散法对香椿嫩芽和老叶萃取物的氯仿、乙酸乙酯和正丁醇萃取部分的抗菌活性进行了研究.嫩芽萃取物的抗菌活性明显高于老叶萃取物,其中嫩芽萃取物的乙酸乙酯部分表现出最强的抗菌活性,其最小抑菌浓度(MIC)为1.3 mg/mL.实验结果表明,香椿叶中的抑菌物质随着生长时间的延长而逐渐降低.     

Nano silver entrapped in phospholipids membrane: Synthesis,characteristics and antibacterial kinetics

Abstract

The antimicrobial property of stabilized silver nanoparticles (AgNPs) with phospholipid membrane was investigated on both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial strains. The influence of phospholipid concentrations on antibacterial kinetics actions of AgNPs was studied with two different methodologies in order to understand the bactericidal and bacteriostatic effects. The bacterial inactivation of synthesized AgNPs fitted well to the Chick-Watson model with a high regression coefficient, R² > 0.91. The antibacterial properties of AgNPs depend on the particle size, stabilizer and lecithin concentrations. Only the stabilized AgNPs that have the K_lec/Ag values of 1 and 2 presented the inhabitation zone, while unstabilized AgNPs agglomerated quickly, settled on the wells and did not diffuse in agar. In addition, the specific coefficient of lethality depends on the lecithin concentration. An increase in lecithin concentration caused multilayer creation on the AgNPs' surface and reduced the release of AgNPs which led to low bacterial killing rate.     

Characterization and functional study of a Cecropin‐like peptide from the Chinese oak silkworm,Antheraea pernyi

In present study, a Cecropin‐like peptide from Antheraea pernyi (ApCec) was cloned and characterized. The full‐length ApCec cDNA encoded a protein with 64 amino acids including a putative 22‐amino‐acid signal peptide, a 4‐amino‐acid propeptide, and a 38‐amino‐acid mature peptide. ApCec gene was highly expressed in Malpighian tubules of A. pernyi after induction for 24 h by Escherichia coli in PBS. Pro‐ApCec (including propeptide and mature peptide) and M‐ApCec (just mature peptide) were synthesized chemically and analyzed by HPLC and mass spectroscopy. The antibacterial activity of M‐ApCec is more potent than pro‐ApCec against E. coli K12 or B. subtilus in both minimum inhibitory concentration and inhibition zone assays. Hemolytic assay results showed M‐ApCec possessed a low cytotoxicity to mammalian cells. The secondary structure of M‐ApCec forms α‐helical structure, shown by circular dichroism spectroscopy. Transmission electron microscopy analysis suggested that M‐ApCec killed bacteria by disrupting bacterial cell membrane integrity. Our results indicate ApCec may play an important role in defending from pathogenic bacteria in A. pernyi, and it may be as a potential candidate for applications in antibacterial drug development and agriculture.     

Ciprofloxacin: review on developments in synthetic,analytical, and medicinal aspects

In the current practices of antiinfective therapy, ciprofloxacin is a very popular fluoroquinolone having a broad spectrum of activity and diverse therapeutic prospects. The reasons for its wide use include multiresistant pathogens susceptible only to ciprofloxacin. The available clinical evidence suggests the potentially enhanced efficacy of this drug in the treatment of various community acquired and nosocomial infections, e.g. respiratory tract, urinary tract, and skin infections and sexually transmitted diseases. As compared to other agents of its class, the pharmacokinetic profile of ciprofloxacin demonstrates equivalent or greater bioavailability, higher plasma concentrations, and increased tissue penetration, as reflected in the greater volume of distribution. Various molecular modifications of this drug have been made to further improve its characteristics. Several methods of analytical determination of ciprofloxacin and its metabolites in biological fluids employing various techniques have been reported. The present article is focused on the synthetic development, pharmacotherapeutic, and analytical evaluation vistas of ciprofloxacin.     

Callinectin, an Antibacterial Peptide from Blue Crab, Callinectes sapidus, Hemocytes

This paper describes the isolation of an approximately 3.7 kDa, basic, antibacterial peptide (designated callinectin), which represents the major antibiotic activity in blue crab, Callinectes sapidus, hemocytes. A single-step purification using low-pressure cation-exchange chromatology yielded a highly purified (>95%) peptide. Purity was confirmed by C₄ reverse-phase high-performance liquid chromatography (RP-HPLC), native gel electrophoresis, sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), capillary electophoresis, and mass spectral analysis. The partial amino acid sequence obtained via Edman degradation revealed no significant homology to other reported peptides in the Basic Local Alignment Search Tool (BLAST) program database. Received April 21, 1998; accepted July 3, 1998.     

Synthesis,spectroscopic, and antibacterial activity of tetraazamacrocyclic complexes of trivalent chromium,manganese, and iron

A new series of macrocyclic complexes of type [M(TML)X]X₂, where M = Cr(III), Mn(III), or Fe(III), TML is tetradentate macrocyclic ligand, and X = Cl^?, NO₃^?, CH₃COO^? for Cr(III), Fe(III) and X = CH₃COO^? for Mn (III), has been synthesized by condensation of benzil and succinyldihydrazide in the presence of metal salt. The complexes have been so formulated due to the 1:2 electrolytic nature of these complexes as shown by conductivity measurements. The complexes have been characterized with the help of various physicochemical techniques such as elemental analysis, molar conductance, electronic and infrared spectral studies, and magnetic susceptibility. On the basis of these studies, a five-coordinate distorted square pyramidal geometry, in which two nitrogens and two carbonyl oxygen atoms are suitably placed for coordination toward the metal ion, has been proposed for all the complexes. The complexes have been tested for their in vitro antibacterial activity. Some of the complexes show remarkable antibacterial activities against some selected bacterial strains. The minimum inhibitory concentrations shown by these complexes have been compared with those shown by some standard antibiotics such as linezolid and cefaclor.     

Antibacterial,antifungal, insecticidal,cytotoxicity and phytotoxicity studies on Indigofera gerardiana

The antibacterial, antifungal, acute cytotoxicity, phytotoxicity and insecticidal profile of the crude extract and various fractions of Indigofera gerardiana have been studied. Six bacterial and fungal strains were used, of which Samonella typhi and Microsporum canis were the most susceptible strains with MICs 0.37 mg/mL and 0.09 mg/mL, respectively. The crude extract and the fractions showed low insecticidal activity against Sitophilus oryzae, Rhyzopertha dominica and Callosbruchus analis but no activity against Tribolium castaneum. The brine shrimp lethality assay showed absence of any measurable cytotoxicity of the crude extract and fractions, showing a good safety profile at a preliminary level. All the fractions except crude extract revealed profound and highly significant herbicidal activity against Lemna minor at the concentration of 1000 μg/mL. Indigofera gerardiana was shown by in-vitro assays to be a potential source for natural antifungal, antibacterial and herbicidal agents.     

Synthesis,Cytotoxic, and Antibacterial Evaluation of Quinazolinone Derivatives with Substituted Amino Moiety

A series of novel quinazolinone derivatives containing a substituted amino moiety were synthesized, evaluated for their cytotoxic and antibacterial activities. The results of MTT assay showed that all synthesized target compounds 5A  –  5O showed potent cytotoxicity against SGC‐7901 (IC₅₀, 0.72 – 1.41 μm ). Moreover, the compounds 5D , 5I , and 5K showed better selectivity as compared with positive controls pemetrexed and MTX due to weak cytotoxicity against normal tissue cell line HUVSMC. Among synthesized compounds, the compounds 5E , 5J , 5L , and 5N showed broad‐spectrum cytotoxic activities against at least four cancer cell lines at a micromolar level. The results of antibacteria evaluation revealed that all synthesized compounds showed good to moderate antibacterial activities against Gram‐negative bacteria Escherichia coli. Among them, the MIC values of the compounds 5C , 5F , and 5M were 0.31 μg/mL.     

Isolation,Characterization, and Metabolic Profiling of Ceratorhiza hydrophila from the Aquatic Plant Myriophyllum spicatum

The goal of the present study was to investigate the antibacterial properties, enzyme production, and metabolic profiling of a new Ceratorhiza hydrophila strain isolated from the submerged aquatic plant Myriophyllum spicatum. Furthermore, the fungus'' morphological characterization and DNA sequencing have been described. The fungus has been identified and submitted to the GenBank as Ceratorhiza hydrophila isolate EG19 and the fungus ID is {"type":"entrez-nucleotide","attrs":{"text":"MK387081","term_id":"1552064574","term_text":"MK387081"}}MK387081. The enzyme analyses showed its ability to produce protease and cellulase enzymes. According to the CSLI standard, the ethyl acetate extract of C. hydrophila showed intermediate antibacterial activity against Streptococcus pneumonia, Micrococcus luteus, and Staphylococcus aureus. Metabolic profiling has been carried out using 700 MHz NMR spectroscopy. Based on the ¹H and ¹H-¹³C heteronuclear single quantum coherence (HSQC) NMR data and NMR databases, 23 compounds have been identified. The identified metabolites include 31% amino acids, 9% sugars, 9% amines, 4% sugar alcohols, and 4% alkaloids. This is the first report for the metabolic characterization of C. hydrophila, which gave preliminary information about the fungus. It is expected that our findings not only will pave the way to other perspectives in enormous applications using C. hydrophila as a new promising source of antimicrobial agents and essential metabolites, but also it will be valuable in the classification and chemotaxonomy of the species.