Satya B. Paul

Computational analysis of the activity of pongachalcone I against highly resistant bacteria Pseudomonas putida.

TtgR is a multidrug binding protein in the gram negative bacteria Pseudomonas putida (DOTT1E strain) and regulates one of the key mechanisms of its antibiotic resistance by active extrusion of toxic compounds through the membranebound efflux pumps. The paper reports the molecular docking studies of Pongachalcone I, a natural pyranochalcone and reported potent inhibitor of the bacteria, on the transcriptional regulator (TtgR) enzyme (PDB Code: 2UXI) which is a key efflux pump TtgABC operon repressor. Although the bacterium is capable to expel antibiotics like Chloramphenicol, Tetracycline and Naringenin, yet Pongachalcone I has potent activity against it. The work unveils the key roles played by the residues ASN 110 and CYS 137 in the active site of the enzyme, which would be highly beneficial in providing insight into the molecular mechanism of multiple drug recognition and in designing drugs for antibiotic resistance bacteria.

Evaluation of In vitro Antioxidant Activity of Some Plants of Cachar District, Assam.

Abstract The present study was undertaken to evaluate in vitro antioxidant activity of methanolic extract from leaves of four plants viz. Clerodendron colebrookianum Walp. (Verbinaceae), Gnetum gnemon L. (Gnetaceae), Sarcochlamys pulcherrima (Roxb.) Gaud. (Urticaceae), Garcinia lancifolia (Don) Roxb. (Cluciaceae), from Cachar district, Assam, India. DPPH (1,1-diphenyl 2-picrylhydrazyl) radical scavenging capacity, reducing power assay (RPA) and photochemiluminescence (PCL) assay were used for evaluating in vitro antioxidant activity. Total phenolic content (TPC) was estimated by Folin-Ciocalteus method. Sarcochlamys pulcherrima showed highest antioxidant activity (DPPH EC 50 9.70 ±1.51ppm), as compared to C. colebrookianum (121.05 ±1.09ppm), G. gnemon (255.99 ±0.82ppm), and G. lancifolia (344.96 ±0.76ppm). Highest activity of S. pulcherrima was also supported by RPA and PCL and highest TPC (0.33 mg gallic acid equivalent/mg of dry extract) amongst the plants, indicated that phenolic compound are mainly responsible for the activity.

Synthesis, X-ray Diffraction Study and Antimicrobial Activity of Calcium Sulphate Nanocomposites from Plant Charcoal

Calcium sulphate nanocomposite materials (CB) have been synthesised from plant charcoal. Crushed charcoal powder was heated to red hot over a Bunsen burner flame and produced a white material which has been isolated. The surface morphology of the material has been studied by Scanning Electron Microscopy (SEM) and the elements were analyzed by Energy Dispersion Spectroscopy (EDS). To explore the structural features of the materials X-Ray Diffraction (XRD) patterns were recorded. The material showed pronounced inhibitory effects against Streptococcus faecaelis, Bacillus subtilis, Klebsilla pneumoni, E. coli, Proteus vulgaris and Pseudomonas aeruginosa.

Aggregation dependent fluorescence switching in benzothiazole derivative based H-bonded mesogen

ABSTRACT In this work, hydrogen-bonded liquid crystal exhibiting phase dependent fluorescence has been reported. The H-bonded materials were prepared using pyridenyl benzothiazole and alkoxy benzoic acid as H-bond acceptor and donor respectively. The formation of the target materials was confirmed via different spectroscopic technique and their mesogenic behaviour has been studied through polarising optical microscope, differential scanning calorimetry and 2D-X-ray diffraction. The H-bonded mesogenic material showed aggregation dependent fluorescence switching when subjected to transformation from isotropic-nematic-crystalline phase sequence. Computational studies were performed to probe into fluorescence switching behaviour of the mesogenic material. GRAPHICAL ABSTRACT

Ultrasound-accelerated synthesis of quinoline-based luminescent imines exhibiting large Stokes shift

High yield synthesis of quinoline-based fluorescent imines, exhibiting the highest Stokes shift exceeding 380 nm (>18 000 cm–1), is reported in the current publication. Such large difference in the excitation and emission wavelengths is quite unusual. Synthesis of imines was accelerated by ultrasound. Both experimental and theoretical studies have been performed.

Green, One-Pot, Multicomponent Synthesis of Fused-Ring 2-Aminothiazoles

Abstract A facile, green, and efficient Fe(III) chloride, one-pot, multicomponent reaction (MCR) for synthesis of 2-aminothiazole-based compounds is reported. Considering the medicinal importance of fused ring 2-aminothiazoles, this process provides an easy route to the synthesis of this class of compound. Detailed mechanism of the reaction has been discussed. GRAPHICAL ABSTRACT