Synergistic antimicrobial and antiadhesive effects of benzazole derivatives and lactobacillus biosurfactants in vitro.

The investigation and development of novel antimicrobial compounds are central focuses of medical research. In this study, we evaluated benzimidazoles and benzothiazoles derivatives, and biosurfactants produced by Lactobacillus jensenii P6A and Lactobacillus gasseri P65 as potential antimicrobial agents against the Candida tropicalis, C. albicans, and C. krusei, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus saprophyticus. Several biomolecules exhibited antimicrobial activity against clinical isolates of E. coli and C. albicans, with MIC values of 16 µg mL-1, and against S. saprophyticus, E. aerogenes, and K. pneumoniae, with MICs less than 128 µg mL-1. Six azole compounds exhibited antimicrobial activity against C. albicans and E. coli, with MIC values ranging from 64 to 128 µg mL-1, and five showed activity against Candida spp. and A. niger. Both biomolecules also exhibited an antiadhesive effect at varying concentrations, being most efficient against E. aerogenes (64% for the P6A biosurfactant), E. coli (46.4% for the P65 biosurfactant), and S. saprophyticus (39% for the P65 biosurfactant). Azole compounds I06, I16, I17, T04, and T17 were evaluated for their combined antimicrobial effects with biosurfactants against E. coli and C. albicans. In general, these compounds showed a synergistic effect in vitro. Additionally, in vitro cytotoxicity against two cell lines, HL6 tumor cells and normal VERO cells, was assessed. The benzimidazole derivatives I06 and I17 exhibited cytotoxic activity against HL6 tumor cells, with 50% inhibition of cell viability at 6.25 µg mL-1 and 12.5 µg mL-1, respectively. Furthermore, compound I06 was active in all tested cell lines, showing less than 20% inhibition of cell proliferation in VERO cells, suggesting low toxicity. The biosurfactants did not inhibit the growth of either tumor or normal cells. In this context, the development of benzazole derivatives represents a promising alternative for the design of effective antimicrobial agents. The synergistic and cytotoxic effects of the tested compounds were assessed in vitro, with preliminary safety conclusions drawn solely from Vero cell data.