Preliminary screening of some squalenoid derivatives for toxicity towards dermatophytes

We report a preliminary study of the in vitro anti-dermatophyte activity of six squalenoid derivatives that inhibit 2,3-oxidosqualene cyclase and squalene epoxidase: 2-aza-2,3-dihydrosqualene, 22,23-epoxy-2-aza-2,3-dihydrosqualene, azasqualene alcohol, 19-aza-18,19,22,23-tetrahydrosqualene, 2,3-epoxy-19-aza-18,19,22,23-tetrahydrosqualene and hexafluorosqualene epoxide. The tests were done by inoculating 10 microliters of Trichophyton mentagrophytes (Robin) Blanchard or Microsporum canis Bodin homogenate into 1 ml of Sabouraud glucose liquid medium containing serial dilutions from 100 to 0.25 micrograms ml-1 of the substance. For each compound the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) were determined. The most effective compounds were 22,23-epoxy-2-aza-2,3-dihydrosqualene and azasqualene alcohol, with MICs respectively of 3 and 6.25 micrograms ml-1 for each of the two species of dermatophyte. The first of these compounds was the only one to show fungicidal activity over the range of concentrations tested.