Trinuclear heterobimetallic Ni2Ln complexes [L2Ni2Ln][ClO4] (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er; LH3=(S)P[N(Me)NCH-C6H3-2-OH-3-OMe]3): from simple paramagnetic complexes to single-molecule magnet behavior

The reaction of LH3 with Ni(ClO4)(2).6H 2O and lanthanide salts in a 2:2:1 ratio in the presence of triethylamine leads to the formation of the trinuclear complexes [L2Ni2Ln][ClO4] (Ln=La (2), Ce (3), Pr (4), Nd (5), Sm (6), Eu (7), Gd (8), Tb (9), Dy (10), Ho (11) and Er (12) and L: (S)P[N(Me)NCH-C6H3-2-O-3-OMe]3). The cationic portion of these complexes consists of three metal ions that are arranged in a linear manner. The two terminal nickel(II) ions are coordinated by imino and phenolate oxygen atoms (3N, 3O), whereas the central lanthanide ion is bound to the phenolate and methoxy oxygen atoms (12O). The Ni-Ni separations in these complexes range from 6.84 to 6.48 A. The Ni-Ni, Ni-Ln and Ln-O phenolate bond distances in 2-12 show a gradual reduction proceeding from 2 to 12 in accordance with lanthanide contraction. Whereas all of the compounds (2-12) are paramagnetic systems, 8 displays a remarkable ST=(11)/2 ground state induced by an intramolecular Ni. . .Gd ferromagnetic interaction, and 10 is a new mixed metal 3d/4f single-molecule magnet generated by the high-spin ground state of the complex and the magnetic anisotropy brought by the dysprosium(III) metal ion.     

Synthesis and antitubercular activity of substituted novel pyrazoline derivatives

A series of 2-2-methoxy-4-[5-(substituted phenyl)1-(4-pyridylcarbonyl)-4,5-dihydro-1H-3-pyrazolyl] phenoxyacetic acid were synthesized by the reaction between isoniazid (INH) and chalcones, and were tested for their antimycobacterial activity in vitro against Mycobacterium tuberculosis H37Rv and INH resistant M. tuberculosis using BACTEC-460 radiometric system and agar dilution method. Among the synthesized compounds, Compounds II 2-4-[5-(4-hydroxyphenyl)-1-(4-pyridylcarbonyl)-4,5-ihydro-1H-3-pyrazolyl]-2-methoxy phenoxy acetic acid was found to be most active agent against M. tuberculosis H37Rv (MTB) and INH resistant M. tuberculosis (INHR-MTB), with minimum inhibitory concentration of 0.12 microM, when compared to INH 5.6-fold more active against MTB and 78-fold more active against INHR-MTB, respectively.     

Antibiofilm Activity of α-Amylase from Bacillus subtilis S8-18 Against Biofilm Forming Human Bacterial Pathogens

The extracellular α-amylase enzyme from Bacillus subtilis S8-18 of marine origin was proved as an antibiofilm agent against methicillin-resistant Staphylococcus aureus (MRSA), a clinical strain isolated from pharyngitis patient, Vibrio cholerae also a clinical isolate from cholera patient and Pseudomonas aeruginosa ATCC10145. The spectrophotometric and microscopic investigations revealed the potential of α-amylase to inhibit biofilm formation in these pathogens. At its BIC level, the crude enzyme caused 51.81–73.07% of biofilm inhibition. Beyond the inhibition, the enzyme was also effective in degradation of preformed mature biofilm by disrupting the exopolysaccharide (EPS), an essential component in biofilm architecture. Furthermore, the enzyme purified to its homogeneity by chromatographic techniques was also effective in biofilm inhibition (43.83–61.68%) as well as in degradation of EPS. A commercial α-amylase enzyme from B. subtilis was also used for comparative purpose. Besides, the effect of various enzymes and temperature on the antibiofilm activity of amylase enzymes was also investigated. This study, for the first time, proved that α-amylase enzyme alone can be used to inhibit/disrupt the biofilms of V. cholerae and MRSA strains and beholds much promise in clinical applications.     

Comparison of Bacterial Communities in the Throat Swabs from Healthy Subjects and Pharyngitis Patients by Terminal Restriction Fragment Length Polymorphism

Terminal restriction fragment length polymorphism (T-RFLP) analysis was applied to characterize bacterial flora present in the throats of healthy subjects and pharyngitis patients. The 16S?rRNA genes of bacteria present in throat metagenome were amplified by PCR with 6-carboxy-fluorescein (6-FAM)-labeled universal forward primer (27?F) and a universal reverse primer (1513R). The 16S rDNAs were digested with restriction enzymes with 4-bp recognition sites (MspI or RsaI) and analyzed by using an automated DNA sequencer. T-RFLP patterns were numerically analyzed using computer programs. From analysis of the throat bacterial community, patterns derived from MspI and RsaI digested samples of healthy subjects and pharyngitis patients were grouped into different clusters, though RsaI digested samples showed some uncertainty. Pharyngitis throats generated an average species richness of 9 [±2.1 (SD)] and 10 (±2.9) for MspI and RsaI digests, respectively, whereas healthy throats generated 6.3 (±1.2) and 6.1 (±1.5) in MspI and RsaI digests, respectively. These results suggest that samples from pharyngitis patients contain an unexpected diversity of causative bacteria. The pharyngitis throats were colonized with a rich diversity of bacterial species than that of healthy throats. Using T-RFLP, we are able to detect a model bacterium, Streptococcus pyogenes SF370, and T-RF patterns were consistent with the Streptococcal T-RFLP patterns. Our study indicates that T-RFLP analysis is useful for the assessment of diversity of throat bacterial flora and rapid comparison of the community structure between subjects with and without pharyngitis.     

Stereoselective synthesis of sugar-based β-lactam derivatives: docking studies and its biological evaluation

Highly diastereoselective synthesis of cis-β-lactams via [2+2] cycloaddition reactions of sugar-imine derivative possessing free hydroxyl groups at C-2 and C-3 positions and ketenes is described. exo-Approach of sugar-imine with ketene leads to the stereoselective formation of cis product and it is facilitated by hydrogen bonding interaction of C2–OH with carbonyl group of ketene. Docking studies show that these derivatives are having greater affinity towards PBP and it has been validated by in vivo studies. Among the different sugar-based azetidine-2-ones, compounds 6a and 6d were superior in activity to the commercial antibiotic tetracycline.     

Biosynthesis, purification and characterization of silver nanoparticles using Escherichia coli

The application of nanoscale materials and structures, usually ranging from 1 to 100 nanometers (nm), is an emerging area of nanoscience and nanotechnology. Nanomaterials may provide solutions to technological and environmental challenges in the areas of solar energy conversion, catalysis, medicine, and water-treatment. The development of techniques for the controlled synthesis of nanoparticles of well-defined size, shape and composition, to be used in the biomedical field and areas such as optics and electronics, has become a big challenge. Development of reliable and eco-friendly processes for synthesis of metallic nanoparticles is an important step in the field of application of nanotechnology. One of the options to achieve this objective is to use ‘natural factories’ such as biological systems. This study reports the optimal conditions for maximum synthesis of silver nanoparticles (AgNPs) through reduction of Ag⁺ ions by the culture supernatant of Escherichia coli. The synthesized silver nanoparticles were purified by using sucrose density gradient centrifugation. The purified sample was further characterized by UV–vis spectra, fluorescence spectroscopy and TEM. The purified solution yielded the maximum absorbance peak at 420 nm and the TEM characterization showed a uniform distribution of nanoparticles, with an average size of 50 nm. X-ray diffraction (XRD) spectrum of the silver nanoparticles exhibited 2θ values corresponding to the silver nanocrystal. The size-distribution of nanoparticles was determined using a particle-size analyzer and the average particle size was found to be 50 nm. This study also demonstrates that particle size could be controlled by varying the parameters such as temperature, pH and concentration of AgNO₃.     

In Vitro and In Silico Interaction Studies with Red Wine Polyphenols against Different Proteins from Human Serum

Previous reports have shown that consumption of wine has several health benefits; however, there are different types of wine. In the present study, red wines were investigated for their compositions of active ingredients. The interaction of each component in terms of its binding mode with different serum proteins was unraveled, and the components were implicated as drug candidates in clinical settings. Overall, the study indicates that red wines have a composition of flavonoids, non-flavonoids, and phenolic acids that can interact with the key regions of proteins to enhance their biological activity. Among them, rutin, resveratrol, and tannic acid have shown good binding affinity and possess beneficial properties that can enhance their role in clinical applications.