Synthesis and biological activities of some 1,3-benzoxazol-2(3H)-one derivatives as anti-quorum sensing agents.

Antibiotics are commonly used to treat microbial infections. Due to misuse or large-scale use of antibiotics, many pathogens have gained resistance which makes antibiotic treatments ineffective. The discovery that many bacteria use quorum sensing (QS) to regulate their virulence factor and pathogenicity production makes the QS system an attractive target for antimicrobial therapy. A series of 1,3-benzoxazol-2(3H)-one derivatives were designed and synthesized as QS inhibitors (QSIs) and tested for their QS inhibitory activities. In vitro quorum sensing inhibitor screen (QSIS) assay indicated that the 1,3-benzoxazol-2(3H)-one (compound 1), 5-chloro-1,3-benzoxazol-2(3H)-one (compound 6), 6-methyl-1,3-benzoxazol-2(3H)-one (compound 11), and 5-methyl-1,3-benzoxazol-2(3H)-one (compound 16), inhibit QS system in quorum sensing selector (QSIS)1 strain. These 4 QSIs also significantly reduced elastase production, biofilm formation and swarming motility of Pseudomonas aeruginosa PA01 strain. These results suggest that compound 1, 6, 11 and 16 may provide a starting point for the design and development of new anti-pathogenic drugs that restrict virulence of P. aeruginosa and possibly other clinically important human pathogens. In addition, these QSI molecules could potentially be used in combination with conventional antibiotics to increase the efficiency of disease control and to extend the life span of established antimicrobials.

Studies on analgesic and anti-inflammatory activities of 1-dialkylaminomethyl-2-(p-substituted phenyl)-5-substituted benzimidazole derivatives.

In this study the analgesic and anti-inflammatory activity of 1,2,5-trisubstituted benzimidazole derivatives have been examined. Analgesic activities of these compounds were investigated by using the modified Koster test. Among the compounds synthesized especially compound 1g (1-diethylaminomethyl)-2-(p-chlorophenyl)-5-nitro benzimidazole hydrochloride) has shown higher activity than acetylsalicylic acid (ASA) and indometacin. Compound 1e (1-(diethylaminomethyl)-2-(p-methoxyphenyl)-5-nitro benzimidazole hydrochloride, 1f (1-(diethylaminomethyl)-2-(p-tolyl)-5-nitro benzimidazole hydrochloride and 1i (1-(pipenridinomethyl)-2-(p-methoxyphenyl)-5-nitro benzimidazole hydrochloride) proved as potent as the standard ASA. Therefore the compounds 1e, 1f, 1g and 1i were screened for their anti-inflammatory activities using the carrageenan-induced hind paw edema test. Except 1g all compounds were almost inactive against this model of inflammation compared to indometacin.

Synthesis and antimicrobial activity of 1-dialkylaminomethyl- 2-(p-substituted phenyl)-5-substituted benzimidazole derivatives.

1-(Dialkylaminomethyl)-2-(p-substituted phenyl)-5-substituted benzimidazole derivatives 1 have been synthesized by reacting 2-phenylbenzimidazole derivatives with formaldehyde and a secondary amine. The derivatives of 2-phenylbenzimidazole were obtained by reacting the bisulfide addition product of substituted benzaldehydes with 4-substituted-o-phenylenediamines. Their structures were confirmed by microanalysis, IR and NMR spectral analysis. Antimicrobial activity of the compounds was investigated by the microdilution susceptibility test in Mueller-Hinton Broth and Sabouraud Dextrose Broth was used for the determination of antibacterial and antifungal activities. Test organisms: Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 as Gram-positive bacteria, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 as Gram-negative bacteria, and Candida albicans, C. parapsilosis, C. stellatoidea as yeast-like fungi. Compounds 1a, 1b, 1c, 1e and 1i showed slight to moderate activity against all microorganisms. Compound 1g showed the highest activity. It was found more potent than streptomycin against Enterococcus faecalis and Pseudomonas aeruginosa.