T.R. Ravikumar Naik

Synthesis and DNA cleavage studies of novel quinoline oxime esters

New 2-chloro-3-formyl quinoline oxime esters were synthesized by the reaction of 2-chloro-3-formyl quinoline oximes with various benzoyl chlorides in the presence of triethyl amine and dichloromethane at 0°C. The DNA photo cleavage studies of some new oxime esters were investigated by neutral agarose gel electrophoresis at different concentrations (40μM and 80μM). Analysis of the cleavage products in agarose gel indicated that few of quinoline oxime esters (3d-i) converted into supercoiled pUC19 plasmid DNA to its nicked or linear form.

Nanostructured TiO2 Catalyzed Microwave Assisted Synthesis of Fused Quinolines – DNA Binding, Molecular Docking and Antioxidant Activity

The use of nanostructured TiO2 as mixed phase photocatalyst in the synthesis of 2H-pyrano/2H-thiopyrano [2,3-b]quinoline-2-carboxylic acid (2a/2b) is described. The binding modes of 2a/2b with ds DNA fragments d(CGCGAATTCGCG) were predicted by molecular docking studies. The lowest energy was found in the compound 2b with a binding energy of -7.44 Kcal/mol and inhibition constant of 5.39 x e-6. The interaction study with CT DNA was carried out by absorption spectra, (Kb constant obtained for 2a is 3.5x106 and for 2b it is 2.9x105), viscosity and thermal denaturation methods. The in vitro antioxidant activities were evaluated. Finally, the results showed that the intercalated 2a/2b compounds are strong antioxidants and they protect oxidative DNA damage from harmful free radicals.

Synthesis, DNA Binding, Docking and Photoclevage Studies of Novel Benzo[b][1,8]naphthyridines

The synthesis and docking studies of novel benzo[b][1,8]naphthyridines is discribed. The docking studies show that the derivatives prefer to bind the AT-rich region of double stranded DNA (ds-DNA). The maximum binding energy -7.16 (kcal/mol) was observed for benzo[b][1,8]naphthyridine-5-thiol 5a and it is a better candidate as an enantioselective binder to ds-DNA than the other derivatives of benzo[b][1,8]naphthyridines. When photoirradiated at 365 nm, benzo[1,8]-naphthyridines have been found to promote the photocleavage of plasmid pUC19 DNA.

Synthesis, DNA binding, docking and photocleavage studies of quinolinyl chalcones

A series of simple quinoline–chalcone conjugates have been synthesized by Claisen–Schmidt condensation reactions of substituted acetophenones with 2-chloro-3-formyl-quinoline and evaluated for their nucleolytic activity. The structures of the synthesized quinoline–chalcone conjugates were confirmed by IR, 1H NMR, 13C NMR and mass spectral analyses. Most of the prepared compounds showed significant DNA binding and photocleavage activities. The incorporation of an electron-donating group into ring A caused a moderate increase in the DNA binding and photocleavage activities. Compounds 3c and 3d exhibited promising DNA photocleavage against pUC 19 DNA with 85% inhibition at 100 μM concentration. A structure–activity relationship analysis of these compounds was performed; compounds 3c and 3d are potential candidates for future drug discovery and development.

An efficient one-pot synthesis and photoinduced DNA cleavage studies of 2-chloro-3-(5-aryl-4,5-dihydroisoxazol-3-yl)quinolines

4,5-Dihydroisoxazoles continue to attract considerable interest due to their wide spread biological activities. Here, we identify an efficient protocol for the preparation of 4,5-dihydroisoxazoles (2-isaxazolines) (4a-g) from quinolinyl chalcones. The nucleolytic activities of synthesized compounds were investigated by agarose gel electrophoresis. All these compounds were showed the remarkable DNA cleavage activity (concentration dependent) with pUC19 DNA at 365nm UV light. The DNA cleavage activity was significantly enhanced by the presence of iminyl and carboxy radicals of DIQ.