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Four new naphthyridine derivatives (R1-R4) possessing amino acid or boronic acid moieties have been synthesized and characterized using 1H and 13C NMR, FT-IR, and mass spectral techniques. The mechanism of binding of these probes with calf thymus DNA (CT-DNA) has been delineated through UV-Vis, fluorescence, and circular dichroism (CD) spectral techniques along with thermodynamic and molecular docking studies. Small hypochromicity in absorption maximum of the probes without any shift in wavelength of absorption suggests groove binding mode of interaction of these probes with CT-DNA, confirmed by CD and 1H NMR spectral data competitive binding assay with ethidium bromide (EB). CT-DNA quenches the fluorescence of these probes via a static quenching mechanism. In the case of R1 and R4, the observed ΔHo 0suggest that these probes interact with CT-DNA through H-bonding and hydrophobic interactions, while in the interaction of R2 and R3, van der Walls and H-boding forces are found to be dominant (ΔHo

10-methoxy dibenzo[b,h][1,6]naphthyridine carboxylic acid was successfully synthesized from 3-methoxyaniline by a new route. By utilizing a structure-based epharmacophore developed from the active site of 3-phosphoinositide-dependent kinase-1, a series of nine novel 10-methoxy dibenzo[b,h][1,6]naphthyridinecarboxamides was synthesized and characterized by different spectral techniques. Three of them are found to be active by screening against A549 cell line and showed significant anticancer activity when compared to a marketed lung cancer drug, pemetrexed. The molecular docking and in silico pharmacokinetic predictions provide detailed understanding for utilizing the dibenzo[b,h][1,6]naphthyridine scaffold in future drug discovery and development of PDK1 inhibitors.

A series of 4-(7,7-dimethyl-4-(piperazin-1-yl)-5,6,7,8-tetrahydroquinazolin-2-yl)morpholine substituted sulfonamide and urea derivatives has been synthesized and characterized using spectral techniques. The antiviral activity of these compounds against an avian paramyxo virus (AMPV-1) was screened using MTT assay and found that one of the sulfonamide derivatives (2d) show three-fold higher antiviral activity than Ribavirin, a commercial antiviral drug substance.

A series of six novel 1-(7,7-dimethyl-2-morpholino-5,6,7,8-tetrahydroquinazolin-4-yl)piperidine-4-carboxamide derivatives has been synthesized and characterized using various spectral techniques (1H and 13C NMR, LCMS, IR). The antibacterial activities of these compounds have been screened against nine different Gram-positive and Gram-negative bacterial strains. The results show that quinazoline derivatives containing thiazole ring 2a and 2b exhibit good antibacterial activity amongst the compounds under investigation.

The synthesis of pyrrolo[2,3-d]pyrimidine derivatives by direct aminocarbonylation was demonstrated using solid Co2(CO)8 as a CO source in an autoclave at elevated temperature by reacting an aryl halide scaffold with a variety of amines. Using this method, 12 non-glutamate-type pyrrolo[2,3-d]pyrimidine analogues were prepared. Some compounds exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria.

A series of new 6,6-dimethyl-9-oxo-4,5,6,7,8,9-hexahydropyrazolo[5,1-b]quinazoline substituted benzenesulfonohydrazide and 1,3,4-oxadiazole derivatives has been synthesised and characterised using spectral techniques. The antiviral activity of these compounds against an avian paramyxovirus (APMV-1) has been screened and the results show that some of the compounds possess good antiviral activity

Two new 10-methoxydibenzo[b,h][1,6]naphthyridine-2-carboxamide derivatives (R1 and R2) have been synthesized and characterized using different spectral techniques. The binding of these probes with DNA was investigated using spectral (Electronic, fluorescence, 1H NMR and circular dichroism) and molecular docking studies. These probes exhibited a strong fluorescence around 440 nm upon excitation around 380 nm. Electronic and competitive fluorescence titration studies, in HEPES [(4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid)] buffer/dimethyl sulfoxide (pH 7.4) medium, suggest that these probes bind strongly to DNA, which is substantiated by 1H NMR study. The binding constants are calculated to be 5.3 × 107 and 6.8 × 106 M−1 for R1 and R2, respectively. From the results of spectral studies, it is proposed that the mechanism of binding of these probes with DNA is through minor groove binding mode, which is further confirmed by circular dichroism and molecular docking studies. Initial cell viability screening using MTT (3-[4,5-methylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay shows that normal Vero cells are viable towards these probes at nano molar concentration, which is the concentration range employed in the present study for DNA staining (IC50 in the order of 0.023 mM). The enhancement in fluorescence intensity of these probes upon binding with DNA enables the staining of DNA in agarose gel in gel electrophoresis experiment. The sensitivity of these probes is comparable with that of ethidium bromide and DNA amounts as low as 4 nano gram are detectable. Communicated by Ramaswamy H. Sarma

The coordination geometry around copper(II) in [Cu(imda)(phen)(H2O)] (1) (H2imda = iminodiacetic acid, phen = 1,10-phenanthroline) is described as distorted octahedral while those in [Cu(imda)(5,6-dmp)] (2) (5,6-dmp = 5,6-dimethyl-1,10-phenanthroline) and [Cu(imda)(dpq)] (3) (dpq = dipyrido-[3,2-d:2′,3′-f]-quinoxaline) as trigonal bipyramidal distorted square-based pyramidal with the imda anion facially coordinated to copper(II). Absorption spectral (Kb: 1, 0.60 ± 0.04 × 103; 2, 3.9 ± 0.3 × 103; 3, 1.7 ± 0.5 × 104 M−1) and thermal denaturation studies (ΔTm: 1, 5.70 ± 0.05; 2, 5.5 ± 10; 3, 10.6 ± 10 °C) and viscosity measurements indicate that 3 interacts with calf thymus DNA more strongly than 1 and 2. The relative viscosities of DNA bound to 1 and 3 increase while that of DNA bound to 2 decreases indicating formation of kinks or bends and/or conversion of B to A conformation as revealed by the decrease in intensity of the helicity band in the circular dichroism spectrum of DNA. While 1 and 3 are bound to DNA through partial intercalation, respectively, of phen ring and the extended planar ring of dpq with DNA base stack, the complex 2 is involved in groove binding. All the complexes show cleavage of pBR322 supercoiled DNA in the presence of ascorbic acid with the cleavage efficiency varying in the order 3 > 1 > 2. The highest oxidative DNA cleavage of dpq complex is ascribed to its highest Cu(II)/Cu(I) redox potential. Oxidative cleavage studies using distamycin reveal minor groove binding for the dpq complex but a major groove binding for the phen and 5,6-dmp complexes. Also, all the complexes show hydrolytic DNA cleavage activity in the absence of light or a reducing agent with cleavage efficiency varying in the order 1 > 3 > 2.