Halehatty S. Bhojya Naik

Synthesis of novel benzo[h]quinolines : Wound healing, antibacterial, DNA binding and in vitro antioxidant activity

We have characterized a new class of 2-mercapto/2-selenobenzo[h]quinoline-3-carbaldehyde (3/4). Antibacterial potential of these compounds against a wide range of gram-positive and gram-negative bacteria was studied. The selenium containing compound 4 showed significant inhibition zone on Staphylococcus aureus (22.76+/-0.14), Bacillus subtilis (20.63+/-0.24), and Streptococcus pyogenes (19.54+/-0.20) over sulfur containing compound 3. To validate the ethnotherapeutic claims of the synthetic compounds in skin diseases, wound healing activity was studied, besides antioxidant activity to understand the mechanism of wound healing. The interaction behavior of these compounds with DNA was investigated by absorption spectra (obtained K(b) constant for 3 is 2.7x10(5) and for 4 is 3.8x10(6)), viscosity, and thermal denaturation studies. Finally, the results show that the DNA intercalated 3/4 compounds are strong antioxidants; they show significant wound healing activity and protect oxidative DNA damage from harmful free radical reactions.

An efficient microwave-assisted synthesis of thieno[2,3- b ]quinolines under solvent-free conditions

A novel and efficient method for the synthesis of substituted thieno[2,3-b]quinolines has been developed. A simple one-pot reaction of 3-formyl-2-mercaptoquinolines 2a–l with 1-chloroacetone, 2-chloroacetamide, ethyl chloroacetate and 2-chloro-1-phenylethanone in presence of catalytic amount of potassium carbonate under microwave irradiation and solvent-free conditions gave thieno[2,3-b]quinolin-2-ylethanone derivatives 3a–e, thieno[2,3-b]quinoline-2-carboxamide derivatives 4a–e, ethyl thieno[2,3-b]quinoline-2-carboxylate 5a–e and phenyl(thieno[2,3-b]quinolin-2-yl)methanone derivatives 6a–e compounds respectively. The structures of all the newly synthesised compounds were elucidated on the basis of elemental analysis, IR, 1H NMR and mass spectral data.

A Fast and Large-Scale Synthesis of 3-Formyl-2-mercaptoquinolines

A convenient, efficient, and inexpensive procedure for the synthesis of 3-formyl-2-mercaptoquinolines 2a–l has been developed by a simple one-pot reaction of 3-formyl-2-chloroquinolines 1a–l with sodium sulfide and hydrochloric acid in ethanol. The structures of all the synthesized compounds were elucidated on the basis of elemental analyses and IR, 1 H NMR, and mass spectral data.

A facile synthesis of novel 9-methyl[1,2,3]selenadiazoles[4,5-b]quinoline and 9-methyl[1,2,3]thiadiazole[4,5-b]quinoline as a new class of antimicrobial agents

2-chloro-4-methyl quinoline 2 on condensation with semicarbazide hydrochloride gave its semicarbazone. This on reaction with SeO 2 and SOCl2 yielded a new class of novel selenadiazoles 4 and thiadiazoles 5, respectively. The structure of all the compounds were elucidated on the basis of elemental analysis, IR, 1 H NMR, and the mass spectral data. Some derivatives of 9-methyl[1, 2, 3]selenadiazole[4, 5-b] quinoline and 9-methyl[1, 2, 3]thiadiazole [4, 5-b]quinoline have been screened for antimicrobial activities.

Microwave induced synthesis of thieno[2,3-b]quinoline-2-carboxylic acids and alkyl esters and their antibacterial activity

A series of thieno[2,3-b]quinoline-2-carboxylic acids and alkyl esters, (3a–i) have been synthesized by the condensation of 2-chloro-3-formyl quinolines (1a–c) with thioglycolic acid/alkyl esters under microwave irradiation using anhydrous potassium carbonate. These compounds were characterized by elemental analysis, IR, 1H NMR, and mass spectral studies. Their antibacterial activity was also evaluated.

An efficient Bi(NO3)3 · 5H2O catalyzed multi component one-pot synthesis of novel Naphthyridines

An efficient and environmentally friendly multicomponent synthesis of substituted 1,8-naphthyridines catalyzed by bismuth(III) nitrate pentahydrate [Bi(NO3)3 · 5H2O] under solvent-free microwave irradiation is described. This procedure has such advantages as short reaction time, high yields, and simple workup. The catalyst could be reused several times, keeping its initial activity recycled reactions.An efficient and environmentally friendly multicomponent synthesis of substituted 1,8-naphthyridines catalyzed by bismuth(III) nitrate pentahydrate [Bi(NO3)3 · 5H2O] under solvent-free microwave irradiation is described. This procedure has such advantages as short reaction time, high yields, and simple workup. The catalyst could be reused several times, keeping its initial activity recycled reactions.

Synthesis, DNA binding, and cleavage studies of Co(III) complexes with fused aromatic NO/NN-containing ligands.

Four new Co(III) complexes, namely [Co(cq)3](PF6)3, [Co(phen)2(cq)](PF6)3, [Co(bnp)3] (PF6)3, and [Co(phen)2(bnp)](PF6)3 (where cq = chromeno[2,3-b]quinoline, phen = 1,10-phenanthroline and bnp = dibenzo[b,g][1,8]naphthyridine), were synthesized and structurally characterized. Spectroscopic data suggested an octahedral geometry for all the complexes. Binding studies of these complexes with double-stranded (ds)DNA were analyzed by absorption spectra, viscosity, and thermal denaturation studies. The results revealed that the metal complex intercalates into the DNA base stack as intercalator. The oxidative cleavage activities of the complexes were studied with supercoiled pUC19 DNA using gel electrophoresis and the results show that the complexes have potent nuclease activity.

Microwave Induced One-Pot Synthesis of Some New Thiopyrano[2,3-b]quinolin-2-ones under Solvent-Free Conditions

A series of some new thiopyrano[2,3-b]quinolin-2-one 2a-i have been synthesized by the one pot reaction between 2-mercaptoquinoline-3-carbaldehyde 1a-i and phenoxyacetic acid using TEA catalyst under microwave irradiation in solvent free conditions. The procedure is simple, environmentally benign and occurs in good yields. All the newly synthesized compounds were characterized by elemental analyses, IR, 1H NMR and mass spectral data.

Antibacterial, Molecular Docking, DNA Binding and Photocleavage Studies on Novel Heterocyclic Pyrazoles

The antibacterial activity, in-silico DNA molecular docking, DNA binding and photo cleavage studies of newly synthesized pyrazole is described. Antibacterial potential of these compounds screened against a wide range of Gram-positive and Gram-negative bacteria showed significant zone of inhibition and MIC with standard drug ciproflaxin is investigated. Among all the orientation of binding, fourth orientation showed significant binding and revealed that the binding and docking energy of 4a was -8.62 and -8.66 and inhibition constant 7.46 X e -6 . The absorption spectra showed the dynamic interaction with CT DNA and as proficient DNA intercalator (Kb = 4.5×10 4 M -1 ). The viscosity measurements and thermal denaturation affords the positive results towards DNA intercalation in both the studies. The light induced DNA damage was pragmatic in the absence of various ‘‘inhibitors’’ shows in photo cleavage activities at 360 nm.

Synthesis of Diquinolineno[1,3,7,9]Tetraazacyclododecine-7, 15 (14H, 16H)-Dibenzene, and DNA Binding Studies of Macrocyclic Co(II), Cu(II) Complexes: As New Class of Antimicrobial Agent

The synthesis of macrocyclic ligand, diquinolineno[1,3,7,9]tetraazacyclododecine-7, 15 (14H, 16H)-dibenzene(L), is described. The metal complexes of the type [MLX2], where (M = Co(II) (1), Cu(II) (2) and X = (Cl), have been synthesized by the reaction of ligand(L) with the corresponding metal salts, and characterized by elemental analysis, FT-IR, 1H-NMR and electronic spectra. The binding property of the complexes with CT-DNA was studied by absorption spectra, viscosity measurements, as well as thermal denaturation studies. The absorption spectral results indicate that the complexes (1) and (2) are binds with base pairs of DNA. The intrinsic binding constant Kb had the value 3.8 × 104M −1 for (1) and 3.3 × 104 M−1 for (2), respectively, in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2. The viscosity measurement results show the viscosity of sonicated rod-like DNA fragments increased when the complex were added to the solution of calf thymus-DNA. The synthesized ligand and its metal complexes have been screened for antibacterial and antifungal activities.