In vitro evaluation of new 2-phenoxy-benzo[g][1,2,4]triazolo[1,5-a]quinazoline derivatives as antimicrobial agents.

Previously, seventeen 2-phenoxy-benzo[g][1,2,4]triazolo[1,5-a]quinazoline derivatives were prepared and characterized by physicochemical and spectral means. This study was conducted to evaluate their activities in vitro against five Gram-negative and five Gram-positive of clinically pathogenic bacterial strains and ten fungal strains. The antimicrobial activity was assessed, and the minimum inhibitory concentration values of the tested compounds were determined in µg ml-1, using the diffusion agar technique. The bacterial strains used were Escherichia coli (ATCC 25922), Proteus mirabilis (ATCC 7002), Klebsiella oxytoca (ATCC 700324), Pseudomonas aeruginosa (ATCC 10145), Enterobacter cloacae (ATCC 13047D-5), Bacillus subtilis (NRRL B-543), Enterococcus faecalis (RCMB 0100154-2), Staphylococcus aureus (ATCC 29213), Staphylococcus epidermidis (ATCC 12228), and Streptococcus pyogenes (RCMB 0100174-2). Aspergillus fumigatus (RCMB 02568), Syncephalastrum racemosum (IMI 21178), Geotricum candidum (IMI 329542), Candida albicans (ATCC 10231), Aspergillus niger (IMI 130783), Cryptococcus neoformans (NRRL Y-1518), Candida tropicalis (RCMB 05239), Penicillium expansum (IMI 146655), Microsporum canis (RCMB 0834), and Trichophyton mentagrophytes (RCMB 0925) were used as the fungal strains. Ampicillin and gentamicin were used as reference antibacterial drugs and amphotericin B was used as the reference antifungal drug. The antimicrobial studies revealed that the tested compounds 6-8, 11, 12, and 14-16 showed the highest activities against the bacterial and fungal strains. The current study showed that some benzo[g]traizoloquinazolines displayed remarkable antimicrobial activity and could be used as template for further design of potent antimicrobial agent.