Rajendra S. Dongre

Pharmacophores modeling in terms of prediction of theoretical physico-chemical properties and verification by experimental correlations of novel coumarin derivatives produced via Betti’s protocol

A general, simple and straight forward approach to new substituted coumarin derivatives via Bettis condensation reaction of aromatic aldehydes, coumarin and ammonia precursors has been demonstrated successfully under mild reaction conditions. All the synthesized molecules were characterized on the basis of IR, (1)H NMR, (13)C NMR, Mass spectrometry and Elemental data. We have reported the design and calculated molecular properties of some coumarin derivatives on the basis of hypothetical antibacterial pharmacophores, structures which were designed to interact with both of gram positive and gram negative bacteria. A correlation of structure and activities relationship of these compounds with respect to molecular modeling, Lipinski rule of five, drug likeness, toxicity profiles and other physico-chemical properties of drugs are described and verified experimentally.

Adsorption characterization of Pb(II) ions onto iodate doped chitosan composite: equilibrium and kinetic studies

Iodate doped chitosan (I-CS) composite was synthesized, characterized and used as an adsorbent for adsorption of Pb(II) ions from aqueous solution. The I-CS sorbent was extensively characterized by nitrogen adsorption/desorption to determine the BET surface areas and BJH pore size distribution, elemental analysis, TGA/DSC, FTIR, XRD and SEM. The influences of various chemical parameters viz. pH, contact time, dose of adsorbent and initial metal ion concentration on adsorption performance of Pb(II) ions were analyzed. Equilibrium adsorption isotherm and kinetics of adsorption has also been studied. The BET results exhibited decreased porosity and specific surface area of I-CS composite due to the blockage of internal porous cavities by incorporated iodate. The maximum removal of the Pb(II) ions using I-CS adsorbent was observed at optimum pH 6. The dose of adsorbent on the percentage removal of Pb(II) ions also has a prominent effect and maximum Pb(II) ions mitigation found at 0.5 g L−1 adsorbent dose with 99% efficiency achieved in 4 h. The adsorption of Pb(II) ions shown applicability of the Langmuir and Freundlich adsorption isotherm suggests the existence of both heterogeneous surface and monolayer coverage of adsorbed molecules. The adsorption process follows pseudo-second-order kinetics. This doped composite adsorbent proved to be an effective for adsorption of Pb(II) ions from aqueous solution.

Predictions and correlations of structure activity relationship of some aminoantipyrine derivatives on the basis of theoretical and experimental ground

A series of 4-aminoantipyrine derivatives were produced by condensing aromatic primary amine, namely, 4-aminoantipyrine with different aryl carbonyls which occurred cleanly and efficiently without using any catalyst at room temperature. Their structures were confirmed on the basis of 1H NMR, IR, Mass spectra, and elemental analysis. The synthesized library was screened virtually using versatile bioinformatics parameters owing to the quick access, biological response, and utility of the produced moieties. The virtually screened molecules were subjected to screen practically against certain some strain of microorganisms: Staphylococcus aureus (Gram positive), Pseudomonas vulgaris (Gram positive), Pseudomonas Aeruginosa (Gram negative), and Escherichia coli (Gram negative). A correlation of structure and activities relationship of these compounds with respect to molecular modeling, Lipinski rule of five, drug-likeness, toxicity profiles, and other physico-chemical properties of drugs is described and verified experimentally.

Dibutylamine (DBA): A highly efficient catalyst for the synthesis of pyrano[2,3-d]pyrimidine derivatives in aqueous media

Abstract Annulated pyrano[2,3-d]pyrimidine derivatives were synthesized via one-pot, three-component condensation reactions of various aromatic aldehydes, malononitrile and barbituric acid in aqueous ethanol using dibutylamine (DBA) as catalyst. The potential application of DBA in organic synthesis is increasing rapidly due to its reaction simplicity, minimal reaction time, high yields of the desired products (83–94%) and low cost chemicals. All of the synthesized pyrano[2,3-d]pyrimidine derivatives were characterized by IR, 1H NMR, 13C NMR and mass spectra.

Microwave assisted one-pot catalyst free green synthesis of new methyl-7-amino-4-oxo-5-phenyl-2-thioxo-2,3,4,5-tetrahydro-1H-pyrano[2,3-d]pyrimidine-6-carboxylates as potent in vitro antibacterial and antifungal activity

An efficiently simple protocol for the synthesis of methyl 7 amino-4-oxo-5-phenyl-2-thioxo-2, 3, 4,5-tetrahydro-1H-pyrano[2,3-d]pyrimidine-6-carboxylates via one-pot three component condensation pathway is established via microwave irradiation using varied benzaldehyde derivatives, methylcyanoacetate and thio-barbituric acid in water as a green solvent. A variety of functionalized substrates were found to react under this methodology due to its easy operability and offers several advantages like, high yields (78–94%), short reaction time (3–6 min), safety and environment friendly without used any catalyst. The synthesized compounds (4a–4k) showed comparatively good in vitro antimicrobial and antifungal activities against different strains. The Compounds 4a, 4b, 4c, 4d 4e and 4f showed maximum antimicrobial activity against Staphylococcus aureus, Bacillus cereus (gram-positive bacteria), Escherichia coli, Klebshiella pneumonia, Pseudomonas aeruginosa (gram-negative bacteria). The synthesized compound 4f showed maximum antifungal activity against Aspergillus Niger and Penicillium chrysogenum strains. Streptomycin is used as standard for bacterial studies and Mycostatin as standards for fungal studies. Structure of all newly synthesized products was characterized on the basis of IR, 1H NMR, 13C NMR and mass spectral analysis.

Activated carbon from Luffa cylindrica doped chitosan for mitigation of lead(II) from an aqueous solution

The present study is concerned with the batch adsorption of toxic lead(II) ions from an aqueous solution using activated carbon from a Luffa cylindrica fibers doped chitosan (ACLFCS) biocomposite as an adsorbent. The adsorption experiments were conducted as a function of pH, agitation time, initial lead(II) ion concentration and adsorbent dose. The synthesized biosorbent was characterized by instrumental techniques such as XRD, FTIR, SEM, BET surface area and BJH pore size distribution. XRD analysis revealed that the synthesized ACLFCS adsorbent exhibited broad diffraction peaks, reflecting an amorphous structure. FTIR study showed various functionalities, such as CO, –OH and –NH2, which were responsible for lead(II) adsorption on the ACLFCS biocomposite. The surface morphology of the ACLFCS adsorbent possesses a porous texture with round- and elliptical-shaped voids that can provide adsorption sites for the adsorbate. BJH pore size distribution analysis showed an average pore diameter >2 nm for all chitosan (CS), activated carbon of Luffa cylindrica (ACLF) and ACLFCS adsorbents, corresponding to the presence of a mesoporous structure. Batch adsorption of lead(II) ions was carried out at room temperature wherein the optimum conditions for the maximum adsorption of lead(II) ions were attained at pH 5 with an adsorbent dose of 0.1 g L−1. The equilibrium adsorption isotherm data were fitted by the Langmuir and Freundlich models and the Langmuir isotherm exhibited the best fit with the experimental data. The maximum removal of lead(II) obtained was 98% (experimental) and 112 mg g−1 (from the Langmuir isotherm model). The adsorption kinetics was evaluated using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The adsorption data follows a pseudo-second-order kinetic model. The high uptake of lead(II) ions using ACLFCS indicates an effective and low cost adsorbent for the treatment of water contaminated with lead(II) ions.

Greener Synthetic and Nanotechnological Bridge: Theoretical and Practical Biological Approach Toward the Bactericidal Dual Action Mechanism of Azomethine–Nanosilver Hybrid

ABSTRACT An efficient, clean, cheap, and quick procedure for the condensation of aromatic primary amine, namely, 4-aminophenazone, with different aryl carbonyls to produce azomethines under solvent-free and catalyst-free conditions at room temperature has been described. Their structures were confirmed by 1H-nuclear magnetic resonance (NMR), infrared (IR), mass spectra, and elemental analysis. The corresponding azomethines has been screened virtually using bioinformatical parameters on the basis of hypothetical antibacterial pharmacophore structure designed to interact with both of gram-positive bacteria and gram-negative bacteria. The virtually screened molecules were subjected to screening against certain strains of gram-positive and gram-negative bacteria. Based on the results of initial screening, the bactericidal action of some selected compounds has been increased by hybrid coupling with silver nanoparticles. The results thus obtained are discussed.

Antibacterial activity of synthetic pyrido[2,3-d]pyrimidines armed with nitrile groups: POM analysis and identification of pharmacophore sites of nitriles as important pro-drugs

A clean and simple one-pot multi-component methodology was developed for the preparation of 7-amino-2,4-dioxo-5-aryl-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidine-6-carbonitriles via the reaction of 6-amino uracil, aromatic aldehydes and malononitrile using triethylamine (TEA) base as a catalyst in aqueous ethanol medium at NTP. The reaction protocol has assorted advantages viz.; mild reaction conditions, short reaction time, environmentally friendly procedure, low cost chemicals, and easy isolation of derivatives with excellent yields of bioactive products (85–95%). All the synthesised pyrido[2,3-d]pyrimidines bearing nitrile groups (4a–4h) showed comparatively good in vitro antibacterial activities against Staphylococcus and Bacillus cereus (Gram-positive bacteria) and P. merabitis and S. maresens (Gram-negative bacteria). Nevertheless, compound 4h exhibited the highest antibacterial activity and had an excellent % inhibition as compared to standard streptomycin. Overall, compound 4h had enhanced antibacterial activity compared to its positional isomers compound 4f and compound 4g. This increase in bioactivity going from 4f (R = 4-nitro) to 4h (R = 2-nitro) is attributed to the hydrolysis of the CN to an amide which restores the vital intramolecular interaction between the ortho-nitro-phenyl and amide linkages (ONOδ−⋯Hδ+N) and offers a crucial template for antibacterial NH, O-pharmacophore sites. The synthesized compound 4h was tested to verify that it had fewer side effects than the standard/streptomycin. But, its possible inclusion in selective fungal/viral media viz. HIV or Hepatitis B/C is a subject of further research. This multi-component synthetic protocol uses cheap ingredients like Et3N catalyst and ethanol as the green solvent.

Proficient synthesis of bioactive annulated pyrimidine derivatives: A review

Abstract Syntheses of bioactive annulated pyrimidine derivatives are the most significant tasks in N-heterocyclic chemistry because these compounds have proved to be very attractive and useful for the design of new molecular frameworks of potential drugs with varying pharmacological activities. This review paper summarizes the one-pot multicomponent synthesis of annulated nitrogen- and oxygen-containing heterocycles, such as pyrano[2,3-d]pyrimidines, pyrido[2,3-d]pyrimidines and pyrido[2,3-d;5-6-d]dipyrimidines. The synthetic procedure is based on the chemistry of the domino Knoevenagel-Michael addition mechanism.

Computational analysis for antimicrobial active pyrano[2,3-d]pyrimidine derivatives on the basis of theoretical and experimental ground

Abstract Annulated pyrano[2,3-d]pyrimidine derivatives were synthesized with methoxy, hydroxyl, nitrile and bromine substituents in its skeleton and correlated by electronic effect of substituents on the magnitude of antimicrobial activity. The different electron donating and electron withdrawing substituents of the pyrano[2,3-d]pyrimidine derivatives exerted positive influence on its antimicrobial activity against some Gram positive and Gram negative bacteria such as, Bacillus cereus, Staphylococcus aureus, Klebsiella pneumonia, Pseudomonas aureus and Escherichia coli, respectively. Antibacterial screening revealed that the presence of heteroaryl, cyano and amino groups on pyrano[2,3-d]pyrimidine skeleton increases its penetrating power on bacterial cell wall and becomes more biologically active. All the pyrano[2,3-d]pyrimidine derivatives were characterized by IR, 1H NMR, 13C NMR and mass spectra.