Synthesis,characterization and biological properties of mixed ligand complexes of cobalt(II/III) valproate with 2,9‐dimethyl‐1,10‐phenanthroline and 1,10‐phenanthroline

The synthesis of mononuclear cobalt(II/III) complexes with two different ligands (complex 2: [Co(valp)₂(2,9‐dmp)] and complex 3: [Co(valp)₂(H₂O)(1,10‐phen)]) was investigated and the characterization of both complexes was achieved using IR, UV–Vis, and single crystal X‐ray diffraction. Using single crystal X‐ray diffraction, the crystal structure of each of the complexes was determined. Additionally, the biological activity of these complexes was studied in five gram‐positive and four gram‐negative bacterial strains. Whereas in all gram‐negative bacteria tested, cobalt valproate complexes did not show any anti‐bacterial activity, both complexes had effects on gram positive bacteria. Complex 2 demonstrated good anti‐bacterial activity against all gram‐positive bacteria with inhibition zone diameter (IZD) ranging between 15–28 mm. Complex 3 exhibited low inhibition activity against all gram‐positive bacteria except E. faecalis with IZD ranging between 11.3–13.7 mm. Moreover, as an indication of its uses as industrial catalyst, the rate of bis(p‐nitrophenyl) phosphate (BNPP) hydrolysis when catalyzed by these complexes was measured at different temperatures, concentrations and pH. Complex 2 proved to be a better catalyst to induce the hydrolysis of BNPP.     

Practical synthesis of 1-deoxy-d-xylulose and 1-deoxy-d-xylulose 5-phosphate allowing deuterium labelling

An optimised gram scale synthesis allows the production of 1-deoxy-d-xylulose and 1-deoxy-d-xylulose 5-phosphate with possible deuterium labelling at C-5. Such substrates are required for investigations on the mevalonate-independent 2-C-methyl-d-erythritol 4-phosphate pathway for isoprenoid biosynthesis in bacteria and chloroplasts of phototrophic eukaryotes and for the biosynthesis of vitamins B₁ (thiamine diphosphate) and B₆ (pyridoxol phosphate) in bacteria.     

Bioactive compounds from Iostephane heterophylla (Asteraceae)

The novel bisabolene sesquiterpenes 3-6, were isolated from Iostephane heterophylla, using bioguided fractionation. The new compounds were determined to be (12R/12S)-12,13-epoxy-xanthorrhizols (3,4) and (12R/12S)-12,13-dihydro-12,13-dihydroxy-xanthorrizols (5,6) and their structures were characterized by analysis of spectroscopic data and by chemical correlation from xanthorrhizol (2). The stereochemistry at C-12 of 5 was deduced using the modified Mosher experiment. Some of the isolated compounds elicited activity against gram positive and gram negative bacteria, levadura and dermatophytes.     

Multistep Synthesis of Fluorine‐Substituted Pyrazolopyrimidine Derivatives With Higher Antibacterial Efficacy Based on In Vitro Molecular Docking and Density Functional Theory

Some new fluorine‐substituted pyrazolopyrimidine derivatives ( 1.3 – 1.5 ) have been synthesized by the multistep reactions, starting from reaction of 4‐fluorophenyl malanonitrile ( 1 ) with guanidine, followed by ring closure reaction with hydrazine to give 2,4‐diamino‐6‐aryl‐pyrimidine‐5‐carbonitrile ( 1.2 ). Structure of the compounds was conformed by the spectral and elemental analyses. The antibacterial activity of these compounds was tested in vitro by the disk diffusion assay against two Gram‐positive and two Gram‐negative bacteria, and then the minimum inhibitory concentration was determined with reference to the standard drug chloramphenicol. The results showed that compound 1.5 is better at inhibiting growth as compared with chloramphenicol of both types of bacteria (gram‐positive and gram‐negative). Molecular orbital calculations were carried out by using the density functional theory. The B3LYP/6‐311 + G** level of theory was employed to explore LUMO–HOMO gap energy and charge distribution of compounds 1.1 to 1.5 . Docking studies were performed on bacterial glucosamine‐6‐phosphate synthetase enzyme. Density functional theory calculations and docking studies support the in vitro findings.     

Synthesis and antibacterial activity of isochromene and isoquinoline derivative

Synthesis of 4‐thioureidobenzoic acid ( 2 ), which on cyclization with ethyl chloroacetate gave 4‐(2‐imino‐5‐oxothiazolidin‐3‐yl)‐benzoic acid ( 3 ), which on further reacting with benzoin ( 4 ) in the presence of polyphosphoric acid afforded the synthesis of 2‐imino‐3‐(‐1‐oxo‐3,4‐diphenyl‐1H‐isochromen‐6‐yl) thiazolidin‐5‐one ( 5 ). Compound 5 was then reacted with substituted anilines to give 6‐(2‐imino‐5‐oxothiazolidin‐3‐yl)‐3,4‐diphenyl‐2‐(substituted)‐isoquinolin‐1(2H)‐one (6). The structures of the compounds have been elucidated on the basis of IR 1HNMR, 13C NMR, and elemental analysis. Representative samples were screened for their antimicrobial activity against gram‐negative bacteria, E. coli and P. aeruginosa and gram‐positive bacteria, S. aureus, and C. diphtheriae using disc diffusion method. J. Heterocyclic Chem., (2011).     

Synthesis and antibacterial activity of some imidazo[1,2-a]pyrimidine derivatives.

A series of 75 imidazo[1,2-a]pyrimidine derivatives were synthesized. The "in vitro" antibacterial activity of these compounds and their corresponding alpha-bromoketones against a variety of gram (+), gram (-) bacteria and Mycobacterium species is reported. Some of the prepared derivatives exhibited potent antimicrobial activity.     

Effect of dose rate on inactivation of microorganisms in spices by electron-beams and gamma-rays irradiation

Total aerobic bacteria in spices used in this study were determined to be 1 × 10⁶ to 6 × 10⁷ per gram. A study on the inactivation of microorganisms in spices showed that doses of 6–9kGy of EB (electron-beams) or γ-irradiation were required to reduce the total aerobic bacteria in many However, a little increase of resistance was observed on the inactivation of total aerobic bacteria in many spices in case of EB irradiation. These difference of radiation sensitivities between EB and γ-rays was explained by dose rate effect on oxidation damage to microorganisms from the results of radiation sensitivities of Bacillus pumilus and B. megaterium spores at dry conditions. On the other hand, these high dose rate of EB irradiation suppressed the increase of peroxide values in spices at high dose irradiation up to 80 kGy. However, components of essential oils in spices were not changed even irradiated up to 50 kGy with EB and γ-rays.     

Design,Synthesis, Characterization,and Antimicrobial Activity of Biginelli Products of Indandione

A simple and efficient method has been developed for the synthesis of 4‐(substituted phenyl)‐3,4‐dihydro‐1H‐indeno [1,2‐d] pyrimidine‐2,5‐dione (5) and 4‐(substituted phenyl)‐2‐thioxo‐1,2,3,4‐tetrahydroindeno [1,2‐d] pyrimidine‐5‐one (6) , by a one‐pot three component cyclocondensation reaction of 1,3 dicarbonyl compound (Indandione) (1) , aromatic aldehyde (2) , and urea/thiourea (3/4) using catalytic amount of conc. HCl in refluxing ethanol. Representative samples were screened for their antimicrobial activity against gram‐negative bacteria, E coli and Paeruginosa and gram‐positive bacteria, S aureus, and C diphtheriae using disc diffusion method. The structures of the products were confirmed by IR, ¹H, ¹³C NMR, and elemental analysis.     

Biocidal activity of plasma modified electrospun polysulfone mats functionalized with polyethyleneimine-capped silver nanoparticles

The incorporation of silver nanoparticles (AgNPs) into polymeric nanofibers has attracted a great deal of attention due to the strong antimicrobial activity that the resulting fibers exhibit. However, bactericidal efficacy of AgNP-coated electrospun fibrous mats has not yet been demonstrated. In this study, polysulfone (PSf) fibers were electrospun and surface-modified using an oxygen plasma treatment, which allowed for facile irreversible deposition of cationically charged polyethyleneimine (PEI)-AgNPs via electrostatic interactions. The PSf-AgNP mats were characterized for relative silver concentration as a function of plasma treatment time using ICP-MS and changes in contact angle. Plasma treatment of 60 s was the shortest time required for maximum loss of bacteria (Escherichia coli) viability. Time-dependent bacterial cytotoxicity studies indicate that the optimized PSf-AgNP mats exhibit a high level of inactivation against both gram negative bacteria, Escherichia coli, and gram positive bacteria, Bacillus anthracis and Staphylococcus aureus.     

Novel 1,3,4‐Oxadiazole Derivatives of Dihydropyrimidinones: Synthesis,Anti‐Inflammatory,Anthelmintic, and Antibacterial Activity Evaluation

The present study depicts synthesis of a series of some novel 5‐(5‐(aryl)‐1,3,4‐oxadiazol‐2‐yl)‐3,4‐dihydro‐6‐methyl‐4‐styrylpyrimidin‐2(1H)‐one derivatives. All the newly synthesized compounds were characterized by FTIR, ¹H NMR, ¹³C NMR, mass spectrometry, and elemental analysis. The compounds were evaluated for their in vivo anti‐inflammatory activity by the carrageenan‐induced rat paw edema method. The compounds were also screened for their anthelmintic activity on Indian earthworms and antibacterial activity against some gram positive and gram negative strains of bacteria. This pharmacological activity evaluation revealed that, among all the compounds screened, compounds 4b and 4c were found to have promising anti‐inflammatory activity. Interestingly, compounds 4b , 4c , and 4i exhibited appreciable anthelmintic property, while compounds 4c , 4g , and 4h showed leading antibacterial activity against the selected pathogenic strains of bacteria.     

Multistep, microwave assisted, solvent free synthesis and antibacterial activity of 6-substituted-2,3,4-trihydropyrimido[1,2-c]9,10,11,12-tetrahydrobenzo[b]thieno[3,2-e]pyrimidines

A novel, efficient, microwave assisted route for the synthesis of 6-substituted-2,3,4-trihydropyrimido[1,2-c]-9,10,11,12-tetrahydrobenzo[b]thieno[3,2-e]pyrimidines in good yields has been developed. The intermediates, 2-substituted-4-[3-hydroxy(propyl-1-amino)]5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidines were obtained by irradiating 2-substituted-4-chloro-5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidines with 1-amino-propanol under basic conditions in a microwave oven. 4-Chlorothieno[2,3-d]pyrimidines were synthesized by microwave irradiation of equimolar mixture of 4-hydroxythieno[2,3-d]pyrimidines and phosphorus oxychloride. The final compounds were screened for antibacterial activity by Kirby Bauer's method using amicacin as the standard against various gram positive and gram negative bacteria. All the compounds showed antibacterial activity comparable with the standard.     

Nickel versus copper: enhanced antibacterial activity in a series of new nickel(II) Schiff base complexes

Five new Ni(II) Schiff base complexes [NiL^x(Solv)₂] denoted by NiL^x, x = 1–5, were synthesized and characterized. The Schiff base ligands were synthesized from the condensation of 5-bromo-2-hydroxy-3-nitrobenzaldehyde with different aliphatic and aromatic diamines. The X-ray crystal structure of NiL³ was determined. The ligands and complexes were tested as antibacterial agents against two gram(+) and two gram(?) human pathogenic bacteria. The complexes showed moderate antibacterial activity against both gram type bacteria. The new Ni(II) complexes showed enhanced antibacterial activity compared to the previously reported Cu(II) complexes of the same ligands.     

Studies on the synthesis of spiroheterocycles and their derivatives using dimedone as synthetic precursor

Diarylidene ketones 1a–c, formed by the condensation of acetone with diverse appropriate aryl aldehydes undergo Micheal reaction with dimedone to afford the desired spiro compounds 2a–c. The spirodiarylidene derivatives 3a–l on cyclisation with hydrazine, phenyl hydrazine, hydroxyl amine, urea, thiourea and guanidine carbonate furnish the respective insitu oxidized pyrazole 4a–l, phenylpyrazole 5a–l, isoxazole 6a–l, pyrimidine 7a–l, aminopyrimidine 8a–l. The antibacterial activities of the synthesized compounds have been investigated against the gram negative Escherichia coli and gram positive bacteria Staphylococcus aureus.     

Dual‐Functional Dextran‐PEG Hydrogel as an Antimicrobial Biomedical Material

Microbial infections continually present a major worldwide public healthcare threat, particularly in instances of impaired wound healing and biomedical implant fouling. The development of new materials with the desired antimicrobial property to avoid and treat wound infection is urgently needed in wound care management. This study reports a novel dual‐functional biodegradable dextran‐poly(ethylene glycol) (PEG) hydrogel covalently conjugated with antibacterial Polymyxin B and Vancomycin (Vanco). The hydrogel is designed as a specialized wound dressing that eradicates existing bacteria and inhibits further bacteria growth, while, ameliorating the side effects of antibiotics and accelerating tissue repair and regeneration. The hydrogel exhibits potent antibacterial activities against both gram‐negative bacteria Escherichia coli (E. coli) and gram‐positive bacteria Staphylococcus aureus (S. aureus) with no observable toxicity to mouse fibroblast cell line NIH 3T3. These results demonstrate the immense potential of dextran‐PEG hydrogel as a wound dressing healthcare material in efficiently controlling bacteria growth in complex biological systems.     

FLUORESCENCE SPECTRAL CHANGES OF HEMATOPORPHYRIN DERIVATIVE UPON BINDING TO LIPID VESICLES, Staphylococcus aureus AND Escherichia coli CELLS

Abstract— The binding of hematoporphyrin derivated (Hpd) to lipid vesicles and bacterial membranes was determined by fluorescence spectroscopy. The fluorescence measurements of Hpd in aqueous solutions showed two bands at 613 and 677 nm. In lipid environments of lecithin vesicles the fluorescence spectrum was shifted to 631 and 692 nm, respectively. Hpd was rapidly bound to the cell membrane of Staphylococcus aureus while much less binding occurred in the presence of Escherichia coli. At the same time, spheroplasts of both bacteria were shown to bind Hpd to a similar extent. These results are well correlated with the photoinactivation of the gram positive bacteria with Hpd while the gram negative cells were shown to be resistant. The pH dependence of both Hpd binding to S. aureus as well as the photodynamic inhibitory effect of the same bacteria are similar. It is concluded that the segregation of Hpd to the cell membrane is a prerequisite for its photodynamic effect.     

Corona plasma discharge for rapid analysis of microorganisms by mass spectrometry

Corona plasma discharge provides a rapid and reliable tool for release of biomarkers from gram negative and positive bacteria, spores and viruses for characterization by mass spectrometry.     

动态多孔海绵结构多层膜负载溶菌酶用于抗菌涂层的研究

以聚丙烯酸(PAA)和聚乙烯亚胺(PEI)为构筑单元,运用层层自组装技术制备了聚电解质多层膜.该多层膜具有独特的动态特点——经酸处理后膜内部形成海绵状通孔结构,该海绵结构在饱和水蒸气的处理下,多孔结构能够闭合,重新回到致密的膜结构.借助该种动态多层膜平台,能够简单有效地通过毛细作用力将溶菌酶负载并固定于多层膜中,为制备基于抗菌蛋白的抗菌涂层提供了新的方法.扫描电镜表征了多层膜动态变化过程,激光共聚焦显微镜表征了溶菌酶在膜内的分布情况,并测定了溶菌酶载入量及其释放动力学.进一步的抗菌测试表明该种抗菌涂层在溶菌酶和PEI的共同作用下可以有效地抑制金黄色葡萄球菌.将多层膜同时负载溶菌酶和乳铁蛋白,提升了涂层对大肠杆菌的杀菌效果.     

Exploring the limits of bacterial identification by intact cell-mass spectrometry

The limits of intact cell-mass spectrometry (ICM-MS) were tested with regard to the minimum number of bacterial cells detectable and its power to discriminate mixed-bacterial cultures. The technique is a surface analysis tool, as is supported by evidence showing that mass fingerprints correspond to material desorbed directly from the cell wall. The brief exposure to solvents, which occurs during sample preparation, does not extract internal cellular material. Spectra were collected over the m/z range of 500 to 10,000. The UV absorbing matrices used were found to be highly specific to bacterial gram type: alpha-cyano-4-hydroxycinnamic acid for gram-negative bacteria and 5-chloro-2-mercaptobenzothiazole for gram-positive bacteria. This specificity allows mixed cultures of different gram types to be differentiated by ICM-MS. The minimum number of cells that could reliably give spectra of sufficient data was 10(4) cells (10(7) cells/mL).     

New hemisynthetic manoyl oxide derivatives with antimicrobial activity.

The synthesis and antimicrobial activity of ten labdane-type diterpenes derived from ent-3-beta-hydroxy-13-epi-manoyl oxide (ribenol) is reported. The chloroethyl carbamidic ester 9 showed the strongest antimicrobial activity against all the tested gram (+), gram (-) bacteria and pathogenic fungi. Moreover, the glycoside 11 exhibited an interesting activity against the three tested fungi.     

Antimicrobial polymers containing melamine derivatives. I. Preparation and characterization of chloromelamine‐based cellulose

A reactive melamine derivative, 2‐amino‐4‐chloro‐6‐hydroxy‐s‐triazine (ACHT), was synthesized through the controlled hydrolysis of 2‐amino‐4,6‐dichloro‐s‐triazine. The reaction was characterized with Fourier transform infrared study and elemental analysis. ACHT could react with cotton cellulose at room temperature with a cold‐pad‐batch treatment process. Upon chlorination reactions, the amino group of covalently bound ACHT could be transformed into an N‐halamine structure, providing potent, durable, and rechargeable antimicrobial activities against both gram‐negative and gram‐positive bacteria. The chlorination mechanism and the structure–property relationship of the treated samples were further examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3818–3827, 2004