Synthesis, characterization and in vitro antimicrobial screening studies of some pyridyl-coumarin compounds / Síntesis, caracterización y evaluación antimicrobiana in vitro de algunos derivados de piridil-coumarina

SUMMARY In vitro antimicrobial screening of some pyridyl-coumarin compounds were done against some bacterial and fungal strains in DMF and DMSO. These pyridyl-coumarin compounds were synthesized in the laboratory and their structure was confirmed by different spectroscopic techniques such as IR, 1H NMR, 13C NMR and mass. Some of these compounds exhibited excellent antibacterial activity in both the solvents.

RESUMEN La actividad antimicrobiana in vitro de algunos compuestos derivados de piridil-coumarina se evaluó frente a algunas cepas bacterianas y fúngicas en DMF y DMSO. Las piridil-cumarinas se sintetizaron en el laboratorio y sus estructuras se confirmaron por diferentes técnicas espectroscópicas, tales como IR, 1H NMR, 13C NMR y masas. Algunos de los compuestos que se obtuvieron presentaron buena actividad antibacteriana en ambos solventes.

Synthesis, characterization and antibacterial screening of some Schiff bases derived from pyrazole and 4-amino antipyrine / Síntesis, caracterización y evaluación antibacteriana de algunas bases de Schiff derivadas de pirazol y 4-amino antipirina

Some Schiff bases of pyrazole and 4-amino antipyrine have been synthesized. The antibacterial screening of these synthesized compounds was done in dimethyl forma-mide against four Gram positive bacteria viz. Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidids and Micrococcus luteus, and three Gram negative bacteria viz. Proteus mirabilis, Escherichia coli and Klebsiella aerogenes. It is observed that in comparison to Schiff bases of 4-amino antipyrine, pyrazole Schiff bases are better for inhibition for these selected Gram positive and Gram negative bacterial strains.

Se sintetizaron algunas bases de Schiff a partir de pirazol y 4-amino antipirina. La evaluación de la actividad antibacteriana de estos compuestos en dimetil formamida se realizó frente a cuatro bacterias Gram positivas, Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidids y Micrococcus luteus, y frente a tres bacterias Gram negativas, Proteus mirabilis, Escherichia coli y Klebsiella aerogenes. Se observó mejor inhibición bacteriana frente a las diferentes cepas para las bases de Schiff basadas en pirazol comparadas con aquellas basadas en 4-amino antipirina.

Synthesis, Characterization and Screening of Some Schiff Bases as Potential Antimicrobial Agents.

Schiff bases derived from 4-amino antipyrene were prepared, and IR and NMR spectral analysis characterized their structure. The Schiff bases produced were (1) 4-((4-chlorobenzylidine)amino)- 1,5-dimethyl-1H-pyrazole-3(2H)-one. [SBS-1], (2) 4-((4-hydroxybenzylidine)amino)-1,5-dimethyl- 1H-pyrazole-3(2H)-one. [SBS-2], (3)1,5-dimethyl-2phenyl-4-((3- phenylallylidine)amino) -1Hpyrazole- 3(2H)-one. [SBS-3], (4)4-((4-hydroxy-3-methoxybenzylidine)amino)-1,5- dimethyl-1Hpyrazole- 3(2H)-one. [SBS-4], (5) 4-(benzylidineamino)-1,5 -dimethyl-1H-pyrazole-3(2H)-one. [SBS- 5], (6) 4-((furan-2-ylmethelene)amino)-1,5-dimethyl-1H-pyrazole-3(2H)-one. [SBS-6] and (7) 4-((4- methoxybenzylidine)amino)-1,5- dimethyl-1H-pyrazole-3(2H)-one. [SBS-7]. The antibacterial activity was studied against S. subfava NCIM 2178, B. megaterium ATCC 9885, P. pseudoalcaligenes ATCC 17440, P. vulgaris NCTC 8313, C. freundii ATCC 10787 and E. aerogenes ATCC 13048. The antibacterial activity was done using Agar Ditch method. The antibacterial activity was evaluated in two polar solvents DMSO and DMF. A differential effect of the compounds extracted in a particular solvent (DMSO/DMF) inhibited different bacteria to a different level. It supports the earlier conclusion that antibacterial activity is dependent on molecular structure of the compound, solvent used and the bacterial strain under consideration. However, from the present results, it appears that cinnamaldehyde as side chain with 4-amino antipyrene as central ligand and DMF as a solvent to be best in inhibiting the studied bacterial strains.

In-vitro antimicrobial activity of Psidium guajava l. leaf extracts against clinically important pathogenic microbial strains

The methanol, acetone and N, N-dimethylformamide (DMF) fractions of leaves of Psidium guajava L. were evaluated for antibacterial and antifungal activity. Piperacillin and gentamicin were used as standards for antibacterial assay, while nystatin and flucanazole were used as standards for antifungal assay. 91 clinically important strains were used for the study which were both clinical isolates as well as identified strains. The antibacterial activity was more pronounced against gram-positive bacterial and fungal strains. Moderate activity was shown against the gram-negative bacterial strains studied.

Os extratos de folhas de Psidium guajava L. preparados com metanol, acetona e N,N-formamida foram avaliados quanto a sua atividade antibacteriana e antifúngica. Piperacilina e gentamicina foram empregadas como padrões de atividade antibacteriana e nistatina e fluoconazol com padrões de atividade antifúngica. O estudo foi desenvolvido com noventa e uma cepas de importância clínica, incluindo isolados clínicos e cepas identificadas. A atividade antibacteriana foi mais intensa contra as cepas de bactérias Gram positivas e de fungos. A atividade contra bactérias Gram negativas foi moderada.

In vitro antibacterial activity of the crude methanol extract of Woodfordia fruticosa Kurz. flower (Lythraceae)

The antibacterial activity of the crude methanol extract of Woodfordia fruticosa Kurz. flower was evaluated at two different concentrations by the agar well diffusion method. The methanol extract of the flower exhibited antibacterial activity at varied levels except against Bacillus subtilis and Micrococcus flavus. The methanol extract was most active against Pseudomonas pseudoalcaligenes. The extract was more active against Gram-negative bacteria as compared to Gram-positive. The inhibitory effect of the extract was compared with standard antibiotics, amoxicillin and ciprofloxacin.

A atividade antibacteriana do extrato metanólico bruto da flor Woodfordia fruticosa Kurz. (Lythraceae) foi avaliada em duas concentrações diferentes através do método de difusão em poços. A atividade antibacteriana ocorreu em diferentes níveis, exceto contra Bacillus subtilis e Micrococcus flavus. O extrato metanólico foi mais ativo contra Pseudomonas pseudoalcaligens. O extrato foi mais ativo contra bactérias Gram negativas do que bactérias Gram positivas. O efeito inibitório do extrato foi comparado ao dos antibióticos padrão amoxicilina e ciprofloxacina.