Evaluation of the effect of terpenoid quinones on Trichophyton mentagrophytes by solution and vapor contact.

The antimicrobial activity against two bacterial strains and three fungi of five terpenoid quinones, three related quinones, and a quinone-containing essential oil was investigated by broth dilution and by agar vapor and box vapor assays. All the quinones, except for coenzyme Q10, exhibited their highest activity against Trichophyton mentagrophytes. Thymoquinone showed the most potent activity, not only by solution contact but also by vapor contact, with menadione the next most potent. Alizarin showed high activity only by solution contact. The antibacterial activity was related to the orthoquinone structure (1,2-chloranil and 1,2-naphthoquinone) and the antifungal activity was related to the paraquinone structure (chloranil, ubiquinone 0, thymoquinone, and menadione).