Abstract

In the present paper, the synthesis of 3-(5-phenyl-4,5-dihydro-1H-pyrazol-3-yl)quinolin-2-ol (2a)/(3a) and 3-(2-hydroxyquinolin-3-yl)-5-phenyl-4,5-dihydro-1H-pyrazole-1 carbothioamide(4a) were prepared according to Claisen-Schmidt condensation, viacondensation of 2- hydroxyquinoline-3-carbaldehyde with ketones. Then finally, α, β-unsaturated ketone (3) reacts with hydrazine hydrate, phenylhydrazine and thiosemicarbazide obtained from the corresponding substituted fused-pyarzolequinolines. The newly synthesized compounds were characterized by elemental analysis, IR, ¹H-NMR, and Mass spectral data. The selected compounds were studied for interaction with calf thymus-DNA(CT-DNA) using electronic spectra, viscosity measurements as well as thermal denaturation studies. On binding to CT-DNA, the absorption spectrum underwent bathochromic and hypochromic shifts. The binding constant (K_b) gave value of 5.3´10⁴ M^-1 for (2a) and 6.5´10⁵ M^-1 for (4a). The viscosity measurements indicated that the viscosities of sonicated rod like DNA fragments were increased. The newly synthesized dihydro-pyarzolequinolines derivatives were screened for antimicrobial activities.

Key words: Quinoline, chalcone, pyrazole-1-carbothioamide, DNA binding, viscosity measurement, antimicrobial activity.