Bharat C. Dixit

Synthesis and in vitro antimicrobial activity of some newer quinazolinone–sulfonamide linked hybrid heterocyclic entities derived from glycine

A novel series of 4-(amino or acetamido)-N-{[3-(substituted aryl)-4-oxo-3,4-dihydroquinazolin-2-yl]-methyl}benzenesulfonamide derivatives (1–19) were designed to assimilate 4-quinazolone and sulfonamide moieties in a single molecular framework. To derive entitled hybrid entities with structural diversity, an efficient multi-step synthetic approach initiated from glycine was developed, which involves milder conditions for emphasizing steps viz., reaction in aqueous-media, phosphazo-method of condensation, base mediated selective ester-cleavage, along with key-step, rapid and improved Grimmel’s hetero-cyclization method. The structure of the synthesized compounds was confirmed by physico-chemical characteristics and spectroscopic investigations. All these compounds were screened for their in vitro antimicrobial activity. The minimum inhibitory concentrations of the synthesized compounds against various bacteria (S. aureus, B. cereus, E. coli, K. pneumonia, P. aeruginosa) and fungus (A. niger, C. albicans) was measured by broth microdilution assay. Further, results on the preliminary biological activity indicated that most of the screened compounds have displayed varied degree of inhibitory actions.

Coordination Polymers of 1,8-Bis(8-Hydroxyquinolin-5-yl)-2,7-Dioxaoctane

Coordination polymers of a novel bis(oxine) bidentate ligand, namely 1,8-bis(8-hydroxyquinolin-5-yl)-2,7-dioxaoctane (BQDO) (H 2 L), have been prepared with the metal ions Cu(II), Co(II), Ni(II), Mn(II), and Zn(II). The novel bis(bidentate) ligand (H 2 L) was synthesized by condensation of 5-chloromethyl-8-hydroxyquinoline hydrochloride with butylene glycol in the presence of a base catalyst. All of these coordination polymers and the parent ligand were characterized by elemental analyses and IR spectral studies. The diffuse reflectance spectral studies of all of the coordination polymers also were performed. The number-average molecular weights (M n ) of all of the coordination polymers were determined by nonaqueous conductometric titrations. In order to determine thermal stability trend, thermogravimetric parameters, such as T o (initial decomposition temperature), T 10 (temperature for 10% weight loss), T max. (temperature of maximum rate of degradation), IPDT (integral procedural decomposition temperature), and the activation energy E a of the thermodegradation process were calculated. All of the coordination polymers were also characterized by their magnetic susceptibilities.

Studies on Dyeing Performance of Novel Acid Azo Dyes and Mordent Acid Azo Dyes Based on 2,4-Dihydroxybenzophenone

Novel acid azo and mordent acid azo dyes have been prepared by the coupling of diazo solution of different aminonaphthol sulphonic acids and aromatic amino acids with 2,4-dihydroxybenzophenone. The resultant dyes were characterized by elemental analysis as well as IR and 1H NMR spectral studies. The UV-visible spectral data have also been discussed in terms of structure property relationship. The dyeing assessments of all the dyes were evaluated on wool and silk textile fibers. The dyeing of chrome pretreated wool and silk have also been monitored. The result shows that better hue was obtained on mordented fiber. Results of bactericidal studies of chrome pretreated fibers revealed that the toxicity of mordented dyes against bacteria is fairly good. Dyeing on wool and silk fibers resulted in yellowish pink to reddish brown colourations having excellent light fastness and washing fastness.

Synthesis, Characterization and Glass-Reinforced Composites of Acetone–Formaldehyde–Phenol Resins

Acetone–formaldehyde (AF) resin having the methylol group (–CH2OH) has been prepared and characterized. The condensation of AF resin with phenol (P) was carried out in the presence of alcoholic alkali catalyst at varying ratios of AF:P, namely 1:1, 1:1.5 and 1:2. The resultant AFP resins were characterized by elemental analysis, IR spectral studies, number average molecular weight (M n) estimated by non-aqueous conductometric titration, and thermogravimetry. The curing study of AFP resins with hexamethylene tetramine (HMTA) was monitored by differential scanning calorimetry (DSC) and kinetic parameters were evaluated. Glass-reinforced composites based on the AFP–HMTA system have also been prepared and characterized.

Novel stereoselective 2,3-disubstituted quinazoline-4(3H)-one derivatives derived from glycine as a potent antimalarial lead

An optimization and modification of Grimmels method leading to cyclization and incorporation of glycine linked sulphonamide at position-2 in 4-quinazolin-(3H)-ones was accomplished. Generation of a lipophilic site at position-3 of 4-quinazolinones was explored by synthesis of imines, unfortunately leading to an isomeric mixture of stereoisomers. These stereoisomeric mixtures were further converted to a single isomer utilizing the novel methodology developed by the use of an aprotic solvent system. Moreover, a mixture of (Z)/(E)-isomers and single configuration was identified and ascertained using NMR, HMQC, HMBC and NOESY spectroscopic techniques. The synthesized entities were further screened for their antimalarial efficacy pertaining two active scaffolds 8m and 8s. The active molecules were sent forth for enzyme inhibitory study against presumed receptors h-DHFR and Pf-DHFR computationally as well as in vitro, proving their potency as dihydrofolate reductase inhibitors. The oral bioavailability of these active molecules was also predicted by the study of ADME properties, indicating good bioavailability of the active entities.

Formulation and In Vitro Evaluation of Ofloxacin Tablets using Natural Gums as Binders.

Natural gums are economical, easily available, and useful as tablet binders. In the present investigation, an attempt was made to formulate Ofloxacin tablets using three natural binders, namely Acacia arabica, Hibiscus esculentus, and xanthan gum. Such six batches of Ofloxacin tablets were prepared by using different types and amounts of the natural binders by the wet granulation method. The tablets were analyzed for their hardness, friability, and weight variation, and in vitro release was performed in a phosphate buffer at pH 6.8. The prepared tablets were also evaluated for their various release kinetics and similarity factors f2. The physical properties of the tablets containing the natural binders showed sufficient hardness, desirable disintegration time, and low friability. Their better percentage of drug release was observed as compared to the marketed formulation showing more than 85% drug release within 45 minutes. The in vitro release data was well-fitted into zero-order and the values of release exponent ‘n’ were between 0.303 and 0.514. The high similarity factor f2 of 64.50 was achieved with the best batch in comparison to the marketed tablets. The results obtained indicated that the gum Acacia arabica performed as well as gelatin compared to the other binders for the Ofloxacin tablet formulation.

Development and Evaluation of Cefadroxil Drug Loaded Biopolymeric Films Based on Chitosan-Furfural Schiff Base

Cefadroxil drug loaded biopolymeric films of chitosan-furfural schiff base were prepared by reacting chitosan with furfural in presence of acetic acid and perchloric acid respectively for the external use. Prepared films were evaluated for their strength, swelling index, thickness, drug content, uniformity, tensile strength, percent elongation, FTIR spectral analysis and SEM. The results of in vitro diffusion studies revealed that the films exhibited enhanced drug diffusion as compared to the films prepared using untreated chitosan. The films also demonstrated good to moderate antibacterial activities against selective gram positive and gram negative bacteria.

Synthesis, Characterization and Glass Reinforcement of Urea-Formaldehyde-Phenol Resins

N,N′-dimethylolurea (DMU) was prepared and condensed with phenol (P) in the presence of alcoholic alkali catalyst at varying mole ratios of DMU: P, namely 1:1, 1:1.5 and 1:2. The resultant DMUP resins were characterized by elemental analysis, IR spectral studies, number average molecular weight estimated by nonaqueous conductometric titration and thermogravimetry. The curing study of DMUP resins with hexamethylenetetramine (HEXA) was monitored by differential scanning calorimeter (DSC) and kinetic parameters were evaluated. Glass-reinforced composites based on DMUP-HEXA systems have also been prepared and characterized for chemical, mechanical and electrical properties.

Synthesis, Characterization and Fibre (Glass and Carbon) Reinforced Composites of Poly(Amido-Imide)s

An amino-terminated oligoimide was prepared by the Michael addition reaction of 4, 4′-diamino diphenyl ether bismaleimide (DDEBM) and 4, 4′-diamino diphenyl methane (DDM) at a DDEBM:DDM molar ratio of 1:2. The poly(amido-imide)s (PAI)s were also prepared by condensation of this DDEBM:DDM oligoimide with various aliphatic bisesters. The resultant PAIs were characterized by elemental analysis, IR spectral studies and number average molecular weight (Mn ) estimated by non-aqueous conductometric titration. The curing behaviour of the diglycidyl ether of bisphenol-A (a commercial epoxy resin) (DGEBA)–PAI system was monitored by differential scanning calorimetry (DSC). Unreinforced PAI–epoxy cured products have also been prepared and analysed thermogravimetrically. Glass and carbon fibre reinforced laminates(i.e. composites) of the PAI–epoxy resin system have been prepared and duly characterized. Their mechanical properties have been compared with commercial composites.

Synthesis, Characterization and Glass Reinforced Composites of Acetone-Formaldehyde-m-Cresol Resins

Abstract Acetone-Formaldehyde (AF) resin having methylol group (—CH2OH) has been prepared and condensed with m-cresol (MC) in the presence of alcoholic alkali catalyst at varying ratios of AF:MC; 1:1, 1:1.5 and 1:2. The resultant AF-MC resins were characterized by elemental analysis, IR spectral studies, number average molecular weight (Mn) estimated by non-aqueous conductometric titration and thermogravimetry. The curing study of AF-MC resins with Hexamethylenetetramine (HMTA) was monitored by Differential Scanning Calorimetry (DSC) and kinetic parameters were evaluated. The glass reinforced composites based on AF-MC-HMTA system have also been prepared and characterized.