Synthesis and in vitro antibacterial activities of 7-(4-alkoxyimino-3-hydroxypiperidin-1-yl)quinolone derivatives

<正>A series of novel 7-(4-alkoxyimino-3-hydroxypiperidin-1-yl)quinolone derivatives were designed,synthesized and evaluated for in vitro antibacterial activities.Compounds 8f,8g,8i and 8j with the potencies similar to or better than those of levofloxacin and IMB against Staphylococcus aureus and Staphylococcus epidermidis,worth further investigation.     

Synthesis and in vitro antibacterial activity of 7-(3-amino-6,7-dihydro-2-methyl-2H-pyrazolo[4,3-c] pyridin-5(4H)-yl)fluoroquinolone derivatives

A series of novel 7-(3-amino-6,7-dihydro-2-methyl-2H-pyrazolo[4,3-c]pyridin- 5(4H)-yl)fluoroquinolone derivatives were designed, synthesized and characterized by 1H-NMR, MS and HRMS. These fluoroquinolones were evaluated for their in vitro antibacterial activity against representative Gram-positive and Gram-negative strains. Results reveal that most of the target compounds exhibit good growth inhibitory potency against methicillin-resistant Staphylococcus epidermidis (MRSE) (MIC: 0.25-4 μg/mL) and Streptococcus pneumoniae (MIC: 0.25-1 μg/mL). In addition, compound 8f is 8-128 fold more potent than the reference drugs gemifloxacin (GM), moxifloxacin (MX), ciprofloxacin (CP) and levofloxacin (LV) against methicillin-resistant Staphylococcus aureus 10-05 and Streptococcus hemolyticus 1002 and 2-64 fold more active against methicillin-sensitive Staphylococcus aureus 10-03 and 10-04.     

Three antibacterial naphthoquinone analogues from cultured mycobiont of lichen Astrothelium sp.

<正>A new naphthoquinone compound named 7-hydroxyl-8-methoxyltrypethelone 3 together with two known compounds trypethelone 1 and trypethelone methyl ether 2 was isolated from cultured mycobiont of Astrothelium sp.The structures were elucidated by 1D and 2D NMR spectroscopic analysis as well as comparison with those reported in literatures.Compound 1 displayed significant antibacterial activity against Bacillus subtilis(ATCC 6633),and showed modest antibacterial activity against Staphylococcus aureus col(MRSA)(CGMCC 1.2465),while compounds 2 and 3 showed modest antibacterial activity against Enterococcus faecalis 850E(CGMCC 1.2135) and S.aureus col(MRSA)(CGMCC 1.2465).     

Synthesising protease-stable isopeptides by proteases: an efficient biocatalytic approach on the basis of a new type of substrate mimetics

A biocatalytic route to the 'post-synthesis' formation of Asp/Glu-derived isopeptides is illustrated on the basis of the Staphylococcus aureus V8 protease used as the biocatalyst, a new type of substrate mimetics as the donor peptides, and several acceptor peptides varying in length and sequence.     

Synthesis,Characterization and Antibacterial Activity of New 5-Aryl Pyrazole Oxime Ester Derivatives

Eleven new 1-{5-[4-（benzyloxy）phenyl]-3-methyl-4,5-dihydropyrazol-l-yl} oxime ester dcrivatives were synthesized and characterized by elemental analysis, HRMS, ^1H NMR data. All the compounds were screened for their antibacterial potential in vitro against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The results indicate that compounds 8c and 8f possess potent activity with the minimum inhibitory concentrations（MIC） of 1.562--3.125 ug/mL against all the four bacteria. Compounds 8c, 8e and 8f show moderate inhibition against the DNA gyrase（IC50=1.9--2.5 ug/mL）. On the basis of the biological activities, structure-activity relationship was discussed.     

Bioactive Properties of a Novel Antibacterial Dye Obtained from Laccase-Mediated Oxidation of 8-Anilino-1-naphthalenesulfonic Acid

Fungal laccase obtained from a Cerrena unicolor strain was used as an effective biocatalyst for the transformation of 8-anilino-1-naphthalenesulfonic acid into a green-coloured antibacterial compound, which can be considered as both an antimicrobial agent and a textile dye, simultaneously. The process of biosynthesis was performed in buffered solutions containing methanol as a co-solvent, allowing better solubilisation of substrate. The transformation process was optimised in terms of the buffer pH value, laccase activity, and concentrations of the substrate and co-solvent. The crude product obtained exhibited low cytotoxicity, antibacterial properties against Staphylococcus aureus and Staphylococcus epidermidis, and antioxidant properties. Moreover, the synthesised green-coloured compound proved non-allergenic and demonstrated a high efficiency of dyeing wool fibres.     

Akanthomycin, a new antibiotic pyridone from the entomopathogenic fungus Akanthomyces gracilis

[structure: see text] Organic extracts of the entomopathogenic fungus Akanthomyces gracilis ARS 2910 contained antibiotics active against Staphylococcus aureus. Bioassay-guided fractionation of the CH2Cl2 extract yielded the antibacterial compound akanthomycin as a mixture of atropisomers along with the closely related compounds 8-methylpyridoxatin and cordypyridone C. Akanthomycin was characterized using X-ray crystallography and NMR.     

对苯二甲醛双缩硫代氨基脲的合成与晶体结构

对苯二甲醛双缩硫代氨基脲的合成与晶体结构;杀菌活性     

IDENTIFICATION AND LOCALIZATION OF PHOTOALKYLATED BASES IN DNA FRAGMENTS

Abstract— Antibodies directed toward 8-(2-hydroxy-2-propyI)-deoxyguanosine-5'-monophosphate (8-hpdGMP), a product of the photoalkylation of deoxyguanosine-5'-monophosphate with 2-propanol, were shown to be highly specific and sensitive in detecting 8-hpdGMP residues in photoalkylated DNA.
The antibodies were further used to determine the distribution of modified guanine residues in DNA. The irradiated DNA was digested with restriction enzymes and the fragments obtained were separated electrophoretically and blotted onto diazotized paper. The covalently bound DNA fragments were probed with the antibodies and then with ¹²⁵I Staphylococcus aureus protein A. These experiments indicate a non-random distribution of modified guanine residues in øX174 RF DNA molecules.     

Synthesis and studies of antibacterial activity of pongaglabol

Pongaglabol [8-hydroxy-5-phenyl-furo[2,3-h]benzo(b)pyran-7-one] was synthesized and tested for antibacterial effects againstShigella dysenteriae, Salmonella typhi, Streptococcus β-haemolyticus andStaphylococcus aureus. The synthesized compounds were characterized using UV, IR and¹H NMR spectral data     

Decreased survival of UV-irradiated Staphylococcus aureus in the presence of 8-methoxypsoralen in the post-irradiation plating medium

For Staphylococcus aureus, the presence of 8-methoxypsoralen (8-MOP) in the post-irradiation plating medium increased the lethal effect of far-UV light (FUV; approximately 254 nm) and of 8-MOP plus near-UV light (8-MOP+NUV; approximately 365 nm), an effect similar to that caused by acriflavine which inhibits DNA repair. In the repair-proficient strain, the presence of 8-MOP in the plating medium was almost as effective in inhibiting the repair of damage caused by FUV as that caused by 8-MOP photoadditions. Survival data obtained with Rec(-)-like and Uvr(-)-like strains suggest that 8-MOP in the plating medium, although possibly inhibiting recombination repair, was much more effective in inhibiting excision repair of FUV damage. Regarding 8-MOP+NUV treatment, 8-MOP in the plating medium had a lesser effect in the repair-deficient strains, differing from that observed after FUV treatment, which is consistent with the notion that different types of damage are caused by the two treatments.     

Antibacterial Constituents from Isodon Excisoides

Two new ent‐kaurane diterpenoids, taihangexcisoidesin C (1) and its acetonide, taihangexcisoidesin D (2), along with 9 known compounds were isolated from the leaves of Isodon excisoides. The structures of the new compounds were elucidated using 1D and 2D NMR spectroscopy analysis. Compounds 3‐6 and 8‐9 were tested for their antibacterial activity against Escherichia coli, Staphylococcus aureus, S. epidermidis and S. saprophyticus. Compound 6 showed inhibitory effects on Staphylococcus aureus, S. epidermidis and S. saprophyticus MIC values 32, 16 and 16 μg/mL, respectively. All of the compounds didn't show effects on Escherichia coli (MIC > 10 mg/mL).     

Petrifilm rapid S. aureus Count Plate method for rapid enumeration of Staphylococcus aureus in selected foods: collaborative study

A rehydratable dry-film plating method for Staphylococcus aureus in foods, the 3M Petrifilm Rapid S. aureus Count Plate method, was compared with AOAC Official Method 975.55 (Staphylococcus aureus in Foods). Nine foods-instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard-were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.     

Structure determination of lepidopteran c,self-defence substance produced by silkworm (bombyx mori)

Lepidopteran C is a minor component in a group of lepidopterans which are self-defence substances produced in haemolymph of silkworm. Its structure was determined by the Edman degradation of the whole molecule as well as the fragments obtained by digestion of Staphylococcus aureus V8 protease, proline specific endopeptidase, and trypsin. Although lepidopteran C is similar to A in amino acid sequence, 11 amino acids of A are substituted in the sequence of C.     

Antimicrobial activity and density functional calculations of a supramolecular manganese complex

The density functional theory calculations on the manganese complex ([Mn(8-OHQ)₃] · CH₃OH, 8-OHQ = 8-hydroxyquinoline) is made and its stabilization, molecular orbital composition, orbital energies, and NBO charge distribution have been investigated. The crystal structure of the complex closely resembles the optimized structure. In vitro activities against some antimicrobials (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis) are determined. The antimicrobial activities present a positive correlation between the concentrations and bioactivities of the complex. The relationship between bioactivities and molecular orbitals (HOMO and LUMO orbitals) of the complex is also discussed.     

Synthesis of Gibbilimbols A ～ D and Their ( Z )-Isomers

Gibbilimbols (1) were isolated from the leaves of Piper gibbilimbum in Papua New Guinea, which showed cyto toxicity toward KB nasopharyngal cancer cells (EDs0 2～ 8 μg/mL) and antibacterial activity against Staphylococcus epidermidis and Bacillus cereus (MIC 2 ～4 μg/mL). [1] Only two methods were reported for the synthesis of them,one is a coupling of phenolic part with alkyne, followed by reduction of triple bond by Mori. [2]     

Capillary electrophoretic method for Staphylococcus aureus detection by using a novel antimicrobial peptide

A novel peptide containing antimicrobial sequence and gelatinase cleavage sites was designed for Staphylococcus aureus detection. Since Staphylococcus aureus could secrete gelatinase, the fluorescein labeled peptide GKRWWKWWRRPLGVRGC could be recognized and cleaved. The obtained products were able to be analyzed by capillary electrophoresis with fluorescence detection. To explore the effect of Staphylococcus aureus concentration on enzyme digestion ability of peptide, Staphylococcus aureus with different concentrations were incubated with the peptide. Results indicated that capillary electrophoretic method was efficient for determining Staphylococcus aureus content. Compared with traditional approaches for Staphylococcus aureus detection, capillary electrophoresis possessed higher efficiency, enhanced sensitivity, and low sample consumption. Moreover, the proposed peptide also presented desirable antimicrobial activity. It suggested that the novel antimicrobial peptide used in this research opens a new path of detecting Staphylococcus aureus by capillary electrophoretic method.     

New trends of nanofluids to combat Staphylococcus aureus in clinical isolates

Journal of Thermal Analysis and Calorimetry - Methicillin-resistant Staphylococcus aureus (MRSA), multi-drug-resistant (MDR) Staphylococcus aureus and sensitive Staphylococcus aureus were selected...     

Studies on antibacterial agents. I. Synthesis of substituted 6,7-dihydro-1-oxo-1H,5H-benzo[i,j]quinolizine-2-carboxylic acids

A series of substituted 6,7-dihydro-1-oxo-1H,5H-benzo[i,j]quinolizine-2-carboxylic acids was synthesized and tested for antibacterial activities. Among them, 9-fluoro-6,7-dihydro-5-methyl-8-(4-methyl-1-piperazinyl)-1-oxo-1H,5H- benzo[i,j]quinolizine-2-carboxylic acid (OPC-7241) exhibited potent antibacterial activity against gram-positive and -negative bacteria, including Staphylococcus aureus and Pseudomonas aeruginosa, and 9-fluoro-6,7-dihydro-8-(4-hydroxy-1-piperidyl)-5-methyl-1-oxo-1H, 5H-benzo[i,j]quinolizine-2-carboxylic acid (OPC-7251) showed potent activity characteristically against Propionibacterium acnes.     

稀土三元配合物的低热固相合成、表征及抑菌活性研究

首次在室温条件下通过固相反应制得了镧稀土水杨酸8-羟基喹啉三元配合物La(Hsal)2(hq)(hq=C9H6NO^-;Hsal^-=C7H5COO^-)。采用元素分析、红外光谱、X射线粉末衍射、热重-差热分析等手段对配合物进行了表征。同时还初步分析了固相反应的机理。抑菌实验表明该配合物对大肠杆菌、金黄色葡萄球菌、白色念珠菌、芽孢杆菌都有很好的抑菌效果。