Antibacterial activity of long-chain fatty alcohols against Staphylococcus aureus

The antibacterial activity against Staphylococcus aureus of long-chain fatty alcohols was investigated, with a focus on normal alcohols. The antibacterial activity varied with the length of the aliphatic carbon chain and not with the water/octanol partition coefficient. 1-Nonanol, 1-decanol and 1-undecanol had bactericidal activity and membrane-damaging activity. 1-Dodecanol and 1-tridecanol had the highest antibacterial activity among the long-chain fatty alcohols tested, but had no membrane-damaging activity. Consequently, it appears that not only the antibacterial activity but also the mode of action of long-chain fatty alcohols might be determined by the length of the aliphatic carbon chain.     

Protective effects of various Chinese traditional medicines against experimental cholestasis

In a previous paper, we reported that methanol extracts obtained from 13 Chinese traditional medicines showed remarkable choleretic effects in normal rats. This paper examines the protective effects against experimental cholestasis induced by carbon tetrachloride (CCl4) or alpha-naphthylisothiocyanate (ANIT) in rats. No medicines, including sodium dehydrocholate and 1-phenylpropanol which are used clinically as choleretic drugs, inhibited the decrease of bile flow induced by CCl4. On the other hand, Intinko-to, Saiko-seikan-to and Bohu-tusyo-san revealed marked improvement of the dysfunction in bile secretion induced by ANIT. These three medicines inhibited the decrease of excretion of bile acid or bilirubin in the bile. They also exerted a protective effect against the alterations of serum components induced by ANIT, i.e., of glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, alkaline phosphatase and the concentration of serum bilirubin. These results indicate that methanol extracts of Intinko-to, Saiko-seikan-to and Bohu-tusyo-san demonstrate not only choleretic effects but also improvement of cholestasis and liver parenchymal injury in rats.     

Antimicrobial and anti-biofilm activity of tannic acid against Staphylococcus aureus

Tannic acid, a rich of natural and process-derived phenolic compound, has been shown to be an effective antagonist against viruses and bacteria. In this study, we determined the antimicrobial activity and mechanisms of tannic acid against Staphylococcus aureus with emphasis on inhibiting effect on biofilm formation. Based on the results of time-kill assay, binding ability assay, lysozyme susceptibility assay and the transmission electron microscope, we tentatively speculated that peptidoglycan might be the target of the process that tannic acid destroy the integrity of cell wall, moreover, tannic acid could reduce the biofilm formation at sub-MIC concentrations. These results manifested that natural product tannic acid could serve as a potentially effective candidate for development of novel strategies to treat methicillin-resistant S. aureus infections.     

Spermine increases bactericidal activity of silver-nanoparticles against clinical methicillin-resistant Staphylococcus aureus

Spermine can effectively reinforce the antibacterial activity of AgNPs.     

Antibacterial Activity of Chinese Red Propolis against Staphylococcus aureus and MRSA

The antibacterial activity of propolis has long been of great interest, and the chemical composition of propolis is directly dependent on its source. We recently obtained a type of propolis from China with a red color. Firstly, the antibacterial properties of this unusual propolis were determined against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). Studies on its composition identified and quantified 14 main polyphenols of Chinese red propolis extracts (RPE); quantification was carried out using liquid chromatography triple quadrupole tandem mass spectrometry (LC-QQQ-MS/MS) and RPE was found to be rich in pinobanksin, pinobanksin-3-acetate, and chrysin. In vitro investigations of its antibacterial activity revealed that its activity against S. aureus and MRSA is due to disruption of the cell wall and cell membrane, which then inhibits bacterial growth. Despite its similar antibacterial activities against S. aureus and MRSA, metabolomic analysis further revealed the effects of RPE on bacteria metabolism were different. The untargeted metabolomic results showed that a total of 7 metabolites in 12 metabolic pathways had significant changes (Fold change > 2, p < 0.05 *) after RPE treatment in S. aureus, while 11 metabolites in 9 metabolic pathways had significant changes (Fold change > 2, p < 0.05 *) after RPE treated on MRSA. Furthermore, RPE downregulated several specific genes related to bacterial biofilm formation, autolysis, cell wall synthesis, and bacterial virulence in MRSA. In conclusion, the data obtained indicate that RPE may be a promising therapeutic agent against S. aureus and MRSA.     

An antimicrobial compound isolated from Cinnamomum iners leaves with activity against methicillin-resistant Staphylococcus aureus

This study was designed to investigate the antimicrobial activity of Cinnamomum iners standardized leave methanolic extract (CSLE), its fractions and isolated compounds. CSLE and fractions were subjected to disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests using different Gram positive and Gram negative bacteria and yeast. Within the series of fractions tested, the ethyl acetate fraction was the most active, particularly against methicillin resistant Staphylococcus aureus (MRSA) and Escherichia coli, with MIC values of 100 and 200 μg/mL, respectively. The active compound in this fraction was isolated and identified as xanthorrhizol [5-(1, 5-dimethyl-4-hexenyl)-2-methylphenol] by various spectroscopic techniques. The overall results of this study provide evidence that Cinnamomum iners leaves extract as well as the isolated compound xanthorrhizol exhibit antimicrobial activity for both Gram negative and Gram positive pathogens, especially against MRSA strains.     

Antibacterial activity of phytochemicals isolated from Atractylodes japonica against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has been emerging worldwide as one of the most important problems in communities and hospitals. Therefore, new agents are needed to treat acute oral infections from MRSA. In this study, antibacterial compounds from the roots of Atractylodes japonica (A. japonica) were isolated and characterized. The compounds were isolated from the root extracts using HPLC-piloted activity-guided fractionations. Four A. japonica compounds were isolated and identified as atractylenolide III (1), atractylenolide I (2), diacetylatractylodiol [(6E,12E)-tetradeca-6,12-diene-8,10-diyne-1,3-diol diacetate, TDEYA, 3). and (6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (TDEA, 4), which was obtained by hydrolysis of TDEYA. The minimum inhibitory concentrations (MICs) was determined in the setting of clinical MRSA isolates. Compound 4 showed anti-MRSA activity with a MIC value of 4-32 μg/mL. The overall results provide promising baseline information for the potential use of the extract of A. japonica as well as some of the isolated compounds in the treatment of bacterial infections.     

Antibacterial activity of a new tetracyclic quinolone, No. 5290, against norfloxacin- and ciprofloxacin-resistant strains of Staphylococcus aureus.

The antibacterial activity of a new tetracyclic quinolone, No. 5290, against 25 strains of Staphylococcus aureus clinically isolated in Japan in 1988-1989 was determined. The minimum inhibitory concentrations (MICs) of No. 5290 against both quinolone-susceptible (MIC: norfloxacin less than or equal to 6.25 micrograms/ml, ciprofloxacin less than or equal to 1.56 micrograms/ml) and 4 out of 5 norfloxacin- and ciprofloxacin-moderately resistant strains (MIC: 25 micrograms/ml less than or equal to norfloxacin less than or equal to 50 micrograms/ml, 3.13 micrograms/ml less than or equal to ciprofloxacin less than or equal to 12.5 micrograms/ml) were 0.05 micrograms/ml. Similar findings were obtained on the quinolone-resistant mutants derived by norfloxacin- or KB-5246-selection from quinolone-susceptible clinical isolates of S. aureus. The uptake of No. 5290 into a quinolone-susceptible strain of S. aureus was 2.47 micrograms/mg dry cell and the uptake in norfloxacin- and ciprofloxacin-moderately resistant strains was comparable to that in the quinolone-susceptible strain. The uptake of No. 5290 in both the quinolone-susceptible strain, and norfloxacin- and ciprofloxacin-moderately resistant, and No. 5290-susceptible strains was only slightly influenced by the treatment of bacteria with carbonyl cyanide m-chlorophenylhydrazone. These findings indicate that: (i) No. 5290 has potent antibacterial activity against quinolone-susceptible strains of S. aureus, and the potent activity might be due to a high uptake caused by an ineffective efflux of No. 5290. (ii) No. 5290 also has potent antibacterial activity against norfloxacin- and ciprofloxacin-moderately resistant strains, the reason for which could not be explained by the efflux.     

Synthesis and antibacterial activity of emodin and its derivatives against methicillin-resistant Staphylococcus aureus

Synthesis of the antibacterial emodin was improved using Friedel-Crafts acylation as a key step leading to 37% overall yield. In addition, 21 analogues were synthesized by structural modification of the hydroxyl and methyl groups, as well as the aromatic ring of emodin. Antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and cytotoxicity against noncancerous Vero cells were evaluated. A structure-activity relationship (SAR) study indicated that the hydroxyl groups and the methyl group in the emodin skeleton were crucial for anti-MRSA activity. Furthermore, the presence of an iodine atom or ethylamino group on the aromatic ring enhanced the anti-MRSA activity with higher selectivity indices, while derivatives containing bromine, chlorine atoms or quaternary ammonium salt were as active as emodin. The quaternary ammonium group on the aromatic ring also led to non-cytotoxicity against Vero cells.     

The Antibacterial Activity Mode of Action of Plantaricin YKX against Staphylococcus aureus

We aimed to evaluate the inhibitory effect and mechanism of plantaricin YKX on S. aureus. The mode of action of plantaricin YKX against the cells of S. aureus indicated that plantaricin YKX was able to cause the leakage of cellular content and damage the structure of the cell membranes. Additionally, plantaricin YKX was also able to inhibit the formation of S. aureus biofilms. As the concentration of plantaricin YKX reached 3/4 MIC, the percentage of biofilm formation inhibition was over 50%. Fluorescent dye labeling combined with fluorescence microscopy confirmed the results. Finally, the effect of plantaricin YKX on the AI-2/LuxS QS system was investigated. Molecular docking predicted that the binding energy of AI-2 and plantaricin YKX was −4.7 kcal/mol and the binding energy of bacteriocin and luxS protein was −183.701 kcal/mol. The expression of the luxS gene increased significantly after being cocultured with plantaricin YKX, suggesting that plantaricin YKX can affect the QS system of S. aureus.     

Prediction of the antimicrobial activity of quaternary ammonium salts against Staphylococcus aureus using artificial neural networks

The study of the quantitative structure–activity relationship (QSAR) on antibacterial activity in a series of new imidazole derivatives against Staphylococcus aureus was conducted using artificial neural networks (ANNs). Antibacterial activity against S. aureus was associated with a number of physicochemical and structural parameters of the examined imidazole derivatives. The designed regression and classification models were useful in determining the antibacterial properties of quaternary ammonium salts against S. aureus. The developed models of artificial neural networks were characterized by high predictability (93.57% accuracy of classification, regression model: training data R = 0.92, test data R = 0.92, validation data R = 0.91). ANNs are considered to be a useful tool in supporting the design of synthesis and further biological experiments in the logical search for new antimicrobial substances. Data analysis using ANNs enables the optimization and reduction of labor costs by narrowing the compound synthesis to achieve the desired properties.     

The inhibitory potential of Thai mango seed kernel extract against methicillin-resistant Staphylococcus aureus

Plant extracts are a valuable source of novel antibacterial compounds to combat pathogenic isolates of methicillin-resistant Staphylococcus aureus (MRSA), a global nosocomial infection. In this study, the alcoholic extract from Thai mango (Mangifera indica L. cv. 'Fahlun') seed kernel extract (MSKE) and its phenolic principles (gallic acid, methyl gallate and pentagalloylglucopyranose) demonstrated potent in vitro antibacterial activity against Staphylococcus aureus and 19 clinical MRSA isolates in studies of disc diffusion, broth microdilution and time-kill assays. Electron microscopy studies using scanning electron microscopy and transmission electron microscopy revealed impaired cell division and ultra-structural changes in bacterial cell morphology, including the thickening of cell walls, of microorganisms treated with MSKE; these damaging effects were increased with increasing concentrations of MSKE. MSKE and its phenolic principles enhanced and intensified the antibacterial activity of penicillin G against 19 clinical MRSA isolates by lowering the minimum inhibitory concentration by at least 5-fold. The major phenolic principle, pentagalloylglucopyranose, was demonstrated to be the major contributor to the antibacterial activity of MSKE. These results suggest that MSKE may potentially be useful as an alternative therapeutic agent or an adjunctive therapy along with penicillin G in the treatment of MRSA infections.     

聚类分析辅助中药寡糖电泳分析鉴定中药

基于中药多糖结构的复杂性和特征性,针对多糖部分降解后的寡糖片段,建立了一种采用毛细管区带电泳法(CZE)分离分析中药寡糖,并利用其特征性电泳谱图信息,结合聚类分析(CA)进行中药鉴定的方法。该方法以1-苯基-3-甲基-5-吡唑啉酮(PMP)为寡糖柱前衍生化试剂,对3个科属的6种中药如黄精、玉竹等同时进行鉴定。采用的电泳条件:未涂层熔融石英毛细管柱(49 cm(有效长度40 cm)×50 μm),以50 mmol/L磷酸盐缓冲液(pH 2.5)为运行缓冲液,检测波长为245 nm,运行电压为15 kV,虹吸进样10 cm×4 s,柱温为室温。结果表明聚类分析辅助中药寡糖电泳分析法可有效用于3个科属6种中药的鉴定。本方法结果可靠,重现性好,可以作为中药鉴定的一种有效手段。     

Microcalorimetry combined with chemometics for antibacterial evaluation of Sophora alopecuroides on Staphylococcus aureus

Journal of Thermal Analysis and Calorimetry - As a kind of energetic plasticizer, ester-terminated glycidyl azide polymer (GAPE) has a potential for being mixed with energetic binder glycidyl azide...     

Application of instantaneous nebulization dispersive liquid-phase microextraction combined with HPLC for the determination of chalcone and isoflavone in traditional Chinese medicines

A simple and rapid instantaneous nebulization dispersive liquid-phase microextraction method was developed, and combined with high-performance liquid chromatography for determination of the contents of seven analytes in traditional Chinese medicines. In this study, using the sprinkler device to achieve instantaneous synchronous dispersion and extraction, only one spray can rapidly achieve the concentration and enrichment of seven kinds of chalcone and isoflavones. The key factors affecting the extraction efficiency were optimized including the type and volume of extractant, the pH and salt concentration of the sample phase, and the number of dispersion. Under the optimal conditions, the enrichment factor of the target analytes ranged from 103.1 to 180.9, with good linearity and correlation coefficients above 0.9970. The limits of detection ranged from 0.02 to 0.15 ng/mL, with good accuracy (recoveries 91.1 to 108.9%) and precision (relative standard deviations 1.5–7.1%). This method has short extraction time (2 s), low organic solvent consumption and high enrichment effect, so it has a wide application prospects.     

The antifungal activity of essential oil from Melaleuca leucadendra (L.) L. grown in China and its synergistic effects with conventional antibiotics against Candida

To identify the natural antifungal agents, the antifungal activities of Melaleuca leucadendra (L.) L. essential oil (ML-EO) from Fujian Province of China were assayed. Treatment of ML-EO in combination with the front-line using antibiotics against Candida led to synergistic effects. Electron microscopy analysis on the oil treated C. albicans cells revealed the formation of mesosome-like structures, suggesting well the membrane damage caused by the essential oil. The Griess assay by monitoring NO production in LPS-stimulated RAW264.7 cells indicated the potent anti-inflammatory activity of ML-EO. In comparison with the marked essential oil of Melaleuca alternifolia EO, ML-EO had almost the same chemical components. In general, the antifungal activity of ML-EO and its synergistic interactions with conventional antibiotics were able to lead the development of new treatment strategies on Candida infection.     

Identification and determination of geniposide contained in Gardenia jasminoides and in two preparations of mixed traditional Chinese medicines

A high-performance liquid chromatographic method was applied to the determination of the geniposide concentration in Gardenia fruit and preparations of traditional Chinese medicine using a mobile phase of acetonitrile-methanol-5 mM monosodium phosphate (pH 4.6) (5:15:80, v/v/v). Intra-assay and inter-assay accuracy and precision of the analyses were < or = 10% in the range of 0.1 through 50 microg/ml. The presence of geniposide in the medicinal herb and its preparations was ascertained by retention time, spiking with an authentic standard, change of detection wavelength and change of the composition of the mobile phase. The concentration of geniposide in the fruit of Gardenia jasminoides Ellis var. grandiflora Nakai is higher than that in Gardenia jasminoides Ellis. The concentration of geniposide in the traditional Chinese herbal medicine preparations, Huang-Lian-Jiee-Dwu-Tang (66.27 +/- 1.98 mg/g) and In-Chern-Hau-Tang (68.54 +/- 2.62 mg/g) was less than in the herb Gardenia jasminoides Ellis (73.44 +/- 2.62 mg/g) itself.     

Co-opting the cell wall in fighting methicillin-resistant Staphylococcus aureus: potent inhibition of PBP 2a by two anti-MRSA beta-lactam antibiotics

Methicillin-resistant Staphylococcus aureus (MRSA) is a global bacterial scourge that has become resistant to many classes of antibiotics, and treatment options for MRSA infections are limited. The cause of MRSA resistance to all commercially available beta-lactam antibiotics is the acquisition of the gene mecA, which encodes penicillin-binding protein 2a (PBP 2a). PBP 2a is a transpeptidase, which in contrast to the other transpeptidases of S. aureus does not experience inhibition by beta-lactam antibiotics. The lack of inhibition is due to a closed conformation for the active site for PBP 2a, which opens up only in the course of the catalytic function of the protein. Here we show that two new anti-MRSA antibiotics now undergoing clinical trials, ceftaroline and ME1036, are able to inhibit PBP 2a effectively, a process that is enhanced in the presence of a cell wall structural surrogate. It is likely that in the course of bacterial growth the occupancy of the allosteric site for the cell wall is co-opted by these antibiotics, and under these conditions the second-order rate constant for the encounter of the antibiotic and PBP 2a approaches the clinically useful value of 10(4)-10(5) M-1 s-1. These compounds are potent inhibitors of PBP 2a as well as PBPs from other species, and have potential as therapeutic agents for treatment of serious infections by MRSA and other resistant bacterial pathogens.     

Affinity chromatography with immobilized DNA stationary phase for biological fingerprinting analysis of traditional Chinese medicines

A stationary phase for high performance affinity chromatography with immobilization of DNA onto silica gel was prepared and characterized. The effect of the ionic strength, concentration of Mg2+, EDTA and CH3CN in the mobile phase on the retention of alkaloids were investigated. With this stationary phase, biological fingerprinting analysis of traditional Chinese medicines (TCMs) Coptis chinensis Franch and Rheum palmatum L. was performed with both one-dimensional (1-D) and two-dimensional (2-D) chromatography. The 1-D chromatography was performed with isocratic and gradient elution and 2-D chromatography was developed with immobilized DNA column combined with silica monolithic ODS column. It was found that 7 compounds in Coptis chinensis Franch including berberine, palmatine and jatrorrhizine, 14 compounds in Rheum palmatum L. including aloe-emodin, rhein, emodin, chrysophannol-8-O-glucophranoside and physionl-8-O-glucophranoside were active in binding to the immobilized DNA.     

Microcalorimetric investigation of the antibacterial activity of curcumin on Staphylococcus aureus coupled with multivariate analysis

The antibacterial effect of Curcumin on Staphylococcus aureus growth was evaluated by microcalorimetry. The heat flow power?Ctime curves and nine quantitative parameters of the S. aureus growth were applied to investigate the inhibitory effect with Curcumin. By analyzing these curves and some quantitative parameters using multivariate analytical methods, similarity analysis and principal component analysis, the antibacterial activity of Curcumin on S. aureus could be accurately evaluated from the change of the two main parameters, the second exponential growth rate constant k ₂ and the maximum heat flow power P _m ² . The main two thermal parameters played more important role in the evaluation: at low concentration (0?C10.5???g?mL^?1), Curcumin hardly influence the growth of S. aureus, while at high concentration (10.5?C43.4???g?mL^?1) it could notably inhibit the growth. All these illustrated that the antibacterial activity of Curcumin on S. aureus was enhanced with the increase of the concentration of this compound. This study might provide an useful method and idea accurately evaluate the antibacterial effects of Curcumin, which provides some useful methods for evaluate the nature antibacterial agents.