Kanne Shanker

Ru(II) complexes of N4 and N2O2 macrocyclic Schiff base ligands: Their antibacterial and antifungal studies

Reactions of [RuCl2(DMSO)4] with some of the biologically active macrocyclic Schiff base ligands containing N4 and N2O2 donor group yielded a number of stable complexes, effecting complete displacement of DMSO groups from the complex. The interaction of tetradentate ligand with [RuCl2(DMSO)4] gave neutral complexes of the type [RuCl2(L)] [where L=tetradentate macrocyclic ligand]. These complexes were characterized by elemental, IR, 1H, 13C NMR, mass, electronic, thermal, molar conductance and magnetic susceptibility measurements. An octahedral geometry has been proposed for all complexes. All the macrocycles and macrocyclic Ru(II) complexes along with existing antibacterial drugs were screened for antibacterial activity against Gram +ve (Bacillus subtilis, Staphylococcus aureus) and Gram -ve (Escherichia coli, Klebsiella pneumonia) bacteria. All these compounds were found to be more active when compared to streptomycin and ampicillin. The representative macrocyclic Schiff bases and their complexes were also tested in vitro to evaluate their activity against fungi, namely, Aspergillus flavus and Fusarium species.

Antimicrobial study of newly synthesized 6-substituted indolo[1,2-c]quinazolines

A new series of indolo[1,2-c]quinazoline derivatives were prepared in good yield through reaction of 2-(o-aminophenyl)indole with a variety of arylaldehydes. The structures of the newly synthesized compounds were confirmed by IR, (1)H NMR, (13)C NMR and mass spectral studies and elemental analysis. All the title compounds were investigated for their activity against certain strains of Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis and Streptococcus pyogenes), Gram-negative bacteria (Salmonella typhimurium, Escherichia coli and Klebsiella pneumonia) and pathogenic Fungi (Aspergillus niger, Candida albicans and Trichoderma viridae). Ampicillin and ketoconazole were used as reference compounds. The results revealed that some of synthesized compounds displayed marked activity against all the tested microorganisms.

Mono and bis-6-arylbenzimidazo[1,2-c]quinazolines: a new class of antimicrobial agents.

With the aim of obtaining novel biologically active compounds, we have synthesized a series of mono, bis-2-o-arylideneaminophenylbenzimidazoles and a second series of corresponding mono, bis-6-arylbenzimidazo[1,2-c]quinazolines respectively. The target benzimidazo[1,2-c]quinazoline compounds were obtained by the condensation of 2-(o-aminophenyl)benzimidazole with mono and di carbonyl compounds, followed by oxidative cyclisation of the resulting mono and bis-2-o-arylideneaminophenylbenzimidazoles.All the products were characterized via IR, (1)H NMR, (13)C NMR, MS and elemental analysis. The antimicrobial activities of all quinazolines against various bacteria and fungi were evaluated. Among the compounds tested IVd, IVe exhibited good antibacterial and antifungal activities while IIIb, IIIc also showed notable antimicrobial activity with reference to standard drugs Ampicillin and Ketoconazole respectively.

Physicochemical and biological characterization of novel macrocycles derived from o-phthalaldehyde

A series of novel macrocyclic compounds were synthesized by the condensation of o-phthalaldehyde with aromatic amino alcohols followed by treatment with 1,2-dibromoethane or 1,3-dibromopropane in non-template method. The structural features of the isolated macrocycles have been determined from the microanalytical, IR, (1)H, (13)C NMR and mass spectral studies. Antimicrobial activities of these macrocyclic compounds were tested against the gram-positive (Bacillus subtilis, Staphylococcus aureus) and gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria and found to exhibit potential antibacterial activity. The macrocycles were also tested in vitro to evaluate their activity against fungi, namely, Aspergillus flavus (A. flavus) and Fusarium species.

Synthesis and antimicrobial activities of a new class of 6-arylbenzimidazo[1,2-c]quinazolines

13 C NMR, MS and elemental analysis. The antimicrobial activities of all 6-arylbenzimidazo (1,2-c)quinazolines against three Gram-positive (S. aureus, B. subtilis, S. pyogenes), three Gram-negative (S. typhimurium, E. coli, K. pneumonia) bacteria and three fungal strains (A. niger, C. albicans, T. viridae) were evaluated. Among the compounds tested 13, 19 and 20 showed most potent inhibitory action against test organisms.

6-substituted indolo[1,2-c]quinazolines as new antimicrobial agents.

A series of 2‐o‐arylidineaminophenylindoles and their cyclic derivatives (indolo[1,2‐c]quinazolines) were synthesized. The reactions occurred under relatively mild conditions and afforded the desired product in good yields. Molecular structures of the synthesized compounds were confirmed by IR, 1H‐NMR, 13C‐NMR, MS spectra, and elemental analyses. Furthermore, all the final products were screened for in‐vitro antibacterial activity against three Gram‐positive and three Gram‐negative bacteria and also tested for their inhibitory action against three strains of fungi. Compound IIc showed potent activity against all the bacterial (except S. typhimurium) and fungal strains. Especially, compounds IIi and IIj which have isoquinolyl and pyridyl substituents displayed potent antibacterial as well as antifungal activities compared to those of the respective standard drugs Ampicillin and Ketoconazole.

Synthesis of some new mono, bis-indolo[1, 2-c]quinazolines: evaluation of their antimicrobial studies

A convenient three-step strategy is proposed for the synthesis of mono and bis-indolo[1,2-c] quinazolines from 2-(2-aminophenyl)indole and various aryl aldehydes. The newly synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR, and mass spectroscopic investigation. All the derivatives were screened for antibacterial (S. aureus, B. subtilis, S. pyogenes, S. typhimurium, E. coli, K. pneumonia) and antifungal (A. niger, C. albicans, T. viridae) activities by cup plate method. Among the compounds tested, mono- indolo[1,2-c] quinazolines (15-18) exhibited good antibacterial activities while 15 and 18 also showed notable antifungal activity. Especially, 19 and 20 exhibited stronger antibacterial as well as antifungal activity against all tested strains.

Synthesis of mono, bis-2-(2-arylideneaminophenyl) indole azomethines as potential antimicrobial agents

A series of mono and bis 2-2-(arylidineaminophenyl)indole azomethines have been synthesized by a condensation reaction of 2-(2-amino phenyl) indole with various mono and diketones R-CO-Rl /R-CO-X-CO-Rl (1:1/2:1 ratio) in ethanol media. The synthesized azomethines were characterized via IR, 1H-NMR, 13C-NMR, MS and elemental analysis. The antimicrobial activity of these compounds against different bacteria and fungi was also evaluated.

Encapsulation of Pd(II) by N4 and N2O2 macrocyclic ligands: their use in catalysis and biology

New macrocyclic Schiff base Pd(II) compounds were synthesized by treating N4 and N2O2 macrocycles with palladium chloride in a 1 : 1 ratio. The resulting macrocyclic compounds were characterized by elemental, IR, 1H-NMR, 13C-NMR, mass, molar conductance, magnetic susceptibility, electronic spectra, and thermal analysis. These compounds were used as catalysts in the development of an efficient catalytic method for reduction of organic substrates having nitro, olefinic, acetylenic, and aldehyde groups under mild reaction conditions. The biological activities of all the macrocycles and macrocyclic Pd(II) compounds have been tested against gram positive (Bacillus subtilis and Staphylococcus aureus) and gram negative (Escherichia coli and Klebsiella pneumonia) bacteria and found to be more active than commercially available antibacterial drugs like Streptomycin and Ampicillin.

Hydrolysis of Letrozole catalyzed by macrocyclic Rhodium (I) Schiff-base complexes.

Ten mononuclear Rhodium (I) complexes were synthesized by macrocyclic ligands having N4 and N2O2 donor sites. Square planar geometry is assigned based on the analytical and spectral properties for all complexes. Rh(I) complexes were investigated as catalysts in hydrolysis of Nitrile group containing pharmaceutical drug Letrozole. A comparative study showed that all the complexes are efficient in the catalysis. The percent yields of all the catalytic reaction products viz. drug impurities were determined by spectrophotometric procedures and characterized by spectral studies.