几种中草药提取液对沙门氏菌抑菌效果研究

用醇提和水煎两种方法从30种中草药中筛选抑菌作用显著的4种材料为鹿蹄草、山豆根、石榴皮、五倍子。用二倍稀释法测定测定这4种中草药对沙门氏菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),然后进一步研究其对温度、介质pH、紫外线照射的稳定性。结果表明:鹿蹄草最小抑菌浓度(MIC)为125mg/mL,最小杀菌浓度(MBC)为250mg/mL,五倍子和石榴皮MIC为62.5mg/mL,MBC为125mg/mL,山豆根MIC为250mg/mL,MBC为500mg/mL。温度、介质pH、紫外线照射对这4种中草药提取液稳定性有一定影响。     

An in vitro study on the dental caries preventing effect of oligomeric procyanidins in sorghum episperm

Procyanidins are abundant in sorghum episperm. In this study, the effects of procyanidins from Sorghum bicolor (L.) moench episperm (sorghum procyanidins, SPC) in preventing dental caries were investigated through analysis on SPCs’ effects on cariogenic bacteria and ability in scavenging superoxide anion free radicals. In addition, the SPC with activity in preventing dental caries were identified. The ESI-MS/MS analysis results revealed that the compositions of SPC purified by macroporous resin were dimmers, trimers, tetramers, pentamers and hexamers of procyanidins and catechin/epicatechin monomers. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of SPC on Streptococcus mutans (Ingbritt C) and Streptococcus sobrinus 6715 were 8 and 16 mg/ml, respectively. The SPC had a remarkable inhibition effect (P < 0.05) on acid production of S. sobrinus (Ingbritt C) and S. mutans 6715 compared with the control group, and a dose-dependent relationship was observed. By increasing the concentration of SPC in the experimental condition (200–600 mg/L), the scavenging ratio of superoxide anion radicals increased significantly, indicating that SPC could be used as a potential dental-caries-preventative medicine with its antibacterial and antioxidant ability.     

纳米Ag@TiO2、Fe@TiO2和Zn@TiO2的抑菌活性比较研究

探索常见金属离子掺杂对抑菌片的抑菌性能的影响,为新型纳米TiO₂抑菌片的制备与改善提供技术基础。选择固定质量分数的Ag⁺、Zn²⁺和Fe³⁺掺杂TiO₂,通过抑菌圈、MIC与MBC方法综合评价其抑菌性能,对微观结构进行表征分析,探讨抑菌性能差异的原因。结果表明:抑菌性能大小顺序为Ag@TiO₂> Zn@TiO₂> Fe@TiO₂,Zn@TiO2 的抑菌活性较好但抑菌稳定性差Ag@TiO2对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是10、20 mg/L,Zn@TiO₂对大肠杆菌和金黄色葡萄球菌的MIC、MBC均是30、50 mg/L。表征发现抑菌活性强弱主要归因于纳米TiO₂表面与金属离子共同产生的活性位点数量及稳定性,与孔结构或表面宫能团的关联不大。     

稀土乙酸8-羟基喹啉三元配合物/羟基磷灰石的纳米有机/无机主客体组装复合抗菌生物材料

采用湿法原位合成了Tb、Y、Gd 3种稀土乙酸8-羟基喹啉三元配合物与羟基磷灰石的纳米有机/无机主客体组装复合材料。通过扫描电子显微镜、X射线粉末衍射、红外光谱对样品进行结构分析测定;采用最低抑菌浓度(MIC)和最低杀菌浓度(MBC)实验来检测其抗菌能力。结果表明,  3种复合材料纳米晶平均粒径为50～60 nm,皆对金黄葡萄球菌和大肠杆菌具有较高的抗菌作用,并对金黄葡萄球菌的抑制作用强于大肠杆菌。经过对3种复合材料抗菌作用的比较得出抗菌能力的次序为：  Tb-HQ/HAP < Y-HQ/HAP < Gd-HQ/HAP。     

Construction of functional aliphatic polycarbonates for biomedical applications

Aliphatic polycarbonates are one important kind of biodegradable polymers and have been commonly used as integral components of engineered tissues, medical devices and drug delivery systems. As far as the biomedical application is concerned, traditional aliphatic polycarbonates usually suffer from the strong hydrophobicity, deficient functionality, and insufficient compatibility with cell/organs. Consequently, the application is quite limited in scope. Due to the imparted appealing properties, aliphatic polycarbonates bearing specifically designed functional/reactive groups attract great interest from researchers in the recent years. The present review outlines the development up to date concerning the design and biomedical application of functional aliphatic polycarbonates, with an emphasis on their ring-opening (co)polymerization preparation.     

Evaluation of the antimicrobial activity of aqueous extracts from dry Vaccinium corymbosum extracts upon food microorganism

As blueberries are rich in phenolic compounds, which possess a demonstrated antimicrobial activity, it may be interesting to further elucidate its real potential and properties. As such, the main goal of this work was to evaluate the potential antimicrobial activity of Vaccinium corymbosum dry fruits and leaves aqueous extracts against several contaminants/pathogenic microorganisms while at the same time assessing the effect of V. corymbosum over lactic acid bacteria.     

仿真计算软件在高压共轨电控柴油机标定优化中的应用

为了降低柴油机标定的成本,应用GT—power建立了一款电控高压共轨柴油机的仿真模型。仿真结果与原有的试验数据对比,证明该仿真模型具有足够的精度,可以为Matlabel软件中的Model—Based Calibmtion（MBC）工具箱提供发动机控制参数输入与性能输出的数据库。     

Broad-Spectrum Bactericidal Activity of a Synthetic Random Copolymer Based on 2-Methoxy-6-(4-Vinylbenzyloxy)-Benzylammonium Hydrochloride

Low-molecular-weight organic ammonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Unfortunately, short-term functionality and high toxicity limit their clinical application. On the contrary, the equivalent macromolecular ammonium salts, derived from the polymerization of monomeric ammonium salts, have demonstrated improved antibacterial potency, a lower tendency to develop resistance, higher stability, long-term activity, and reduced toxicity. A water-soluble non-quaternary copolymeric ammonium salt (P7) was herein synthetized by copolymerizing 2-methoxy-6-(4-vinylbenzyloxy)-benzylammonium hydrochloride monomer with N, N-di-methyl-acrylamide. The antibacterial activity of P7 was assessed against several multidrug-resistant (MDR) clinical isolates of both Gram-positive and Gram-negative species. Except for colistin-resistant Pseudomonas aeruginosa, most isolates were susceptible to P7, also including some Gram-negative bacteria with a modified charge in the external membrane. P7 showed remarkable antibacterial activity against isolates of Enterococcus, Staphylococcus, Acinetobacter, and Pseudomonas, and on different strains of Escherichia coli and Stenotrophomonas maltophylia, regardless of their antibiotic resistance. The lowest minimal inhibitory concentrations (MICs) observed were 0.6–1.2 µM and the minimal bactericidal concentrations (MBC) were frequently overlapping with the MICs. In 24-h time–kill and turbidimetric studies, P7 displayed a rapid non-lytic bactericidal activity. P7 could therefore represent a novel and potent tool capable of counteracting infections sustained by several bacteria that are resistant to the presently available antibiotics.     

Inhibitory effects of 4-chlorosalicylic acid on mushroom tyrosinase and its antimicrobial activities

The inhibitory effects of 4-chlorosalicylic acid on the activity of mushroom tyrosinase have been investigated. The results showed that 4-chlorosalicylic acid could strongly inhibit both monophenolase activity and diphenolase activity. The IC₅₀ values were estimated as 1.89 mM and 1.10 mM for monophenolase and diphenolase activities, respectively. For the monophenolase activity, 4-chlorosalicylic acid could not only lengthen the lag time, but also decrease the steady-state rate. For the diphenolase activity, kinetic analyses showed that the inhibition by 4-chlorosalicylic acid was reversible and its mechanism was mixed-II type, which is different from salicylic acid. The inhibition constants (K_I and K_IS) were determined to be 1.51 mM and 0.82 mM, respectively. Furthermore, the antibacterial activity against Escherichia coli, Bacillus subtilis and Staphyloccocus aureus and antifungal activity against Aspergillus niger and Candida boidinii were investigated. The results showed that 4-chlorosalicylic acid was the most effective against E. coli with the MIC of 250 μg/ml and with the MBC of 500 μg/ml.     

The correlation between skin-care effects and phytochemical contents in Lamiaceae plants

In this study, well-known skin-care functional parameters were used, including UV absorption, DPPH-scavenging, NO-production-inhibition, tyrosinase-inhibition activity and anti-Staphylococcus aureus activity to measure the effects of the 70% acetone-extracts form 28 species of Lamiaceae plants. Further, the phytochemical contents were explored by total phenol (TP), total flavone (TF) and total coumarin (TC). The correlation between the skin-care effects and the phytochemical contents was analysed by non-parametric correlation analysis. Amongst the 70% acetone-extracts, Origanum majorana displayed the strongest DPPH-scavenging and tyrosinase-inhibitory effects and the richest phenol content. Based on the statistics results, the phytochemical contents were related with those parameters, such as: DPPH-scavenging effects vs. TP (R = 0.542), TF vs. TP (R = 0.613), and NO-inhibitory vs. anti-bacterial activities (R = 0.767). Moreover, each genus of Lamiaceae had different properties of skin-care effects. Form our research works, the Lamiaceae is good resources to develop skin-care cosmetics.