Background: The present study was carried out to evaluate the antimicrobial
activity of a synthesized 2-methylthio-benzo[g][1,2,4]triazolo[1,5-
a]quinazoline series. The compounds (1-21) were tested against a variety of
Gram-positive bacterial species including Bacillus subtilis (RCMB 01001 69-3),
Enterococcus faecalis (RCMB 0100154-2), Staphylococcus aureus (RCMB
0100183-9), Staphylococcus epidermidis (RCMB 0100183-9) and Streptococcus
pyogenes (RCMB 0100172-5). In addition, Gram-negative bacteria were also
tested including Pseudomonas aeruginosa (RCMB 0100243-5), Escherichia coli
(RCMB 010052-6), Proteus mirabilis (RCMB 01002 54-2), Klebsiella oxytoca
(RCMB 01002 83-4) and Enterobacter cloacae (RCMB 01002 64-5). Furthermore,
their activities were screened against ten types of fungi i.e. Aspergillus fumigatus (RCMB
02568), Syncephalastrum racemosum (RCMB 05922), Geotricum candidum (RCMB 05097), Candida
albicans (RCMB 05036), Aspergillus niger (RCMB 02724), Cryptococcus neoformans (RCMB
05642), Candida tropicalis (RCMBA 05239), Penicillium expansum (RCMB 01924), Microsporum
canis (RCMB 0834) and Trichophyton mentagrophytes (RCMB 0925).
Methods: Evaluation of antimicrobial activity was performed using agar well diffusion method in
comparison with ampicillin and gentamycin as antibacterial reference drugs, and amphotericin B as
antifungal reference drug. The minimum inhibitory concentration (MIC) was determined using the
broth double dilution technique.
Results: The MIC values of the tested compounds were reported in g/mL in which ampicillin, gentamicin
and amphotericin B were used as standard reference drugs. The obtained results revealed that
compounds 3, 4, 7, 8, 9, 10, 11, 14, 17, 18, 19, 20 and 21 showed significant antimicrobial activity
against six bacterial and six fungal strains.
Conclusion: The promising compounds could be employed as useful scaffolds for building of new
derivatives with more potent antimicrobial effects.