Study On The Antifuangal Activities And Mechanism Actions Of Tetralins In Vitro

We adopted the M38-A project recommended by the National Committee ForClinical Laboratory Standard(NCCLS)。Tetralin compounds were tested and selectedwith several candidal albicands and non-candidal strains with different susceptibilities tofluconazole by microal dilution test method. After obtaining the susceptibility results, weplotted the time-growth curves of several typical tetralin compounds, includingcompounds 22-1, 31-1 and their muriate 22,31, as well as compounds 34-1,26-1 and itsbromate 26.We also performed several experiments involving agar disk diffusion test,IC₅₀ value determination test, MFC value determination test, and time-kiU curve test.Results indicated that tetralin compounds had different degrees of antifungal activities,especially 22, 22-1 and 31-1 possessing more powerful antifungal activity. Compounds22 and 22-1 markedly suppressed the growth of Candidal albicands, Candidalparapsiolosis, and Trichophyton rubrum, with all the MIC₅₀ values less than 0.125μg/mland their antifungal capabilities on fluconazole-resistant Candidal albicands were morepowerful than that of ketconazole(p＜0.05). Compound 31-1 had a stronger antifungalactivity to fluconazole susceptible strains than fluconazole did(p＜0.05),and its effectlasted for over 54h at the concentration of 6/μg/ml. Results also confirmed that compound31-1 is possessed of a certain degree of fungicidal activity. The combination effects oftetralin compounds with other antifungal agents(with different structure) were alsodetermined by chess board check assay, agar disk diffusion test and monodrug splitbridge test. Rults indicated that tetralin compounds had a synergistic effect withterbinafine or berberine on fluconazole-resistant strains and a indifferent effect withfluconazole or Amphotericin B. Results of cellular ROS levels determination test showedthat the level of cellular ROS of candida albicands can be obviouslyincreased ,particularly treated by compound 22-1 at the concentration of 6/μg/ml.Weadopted TLC and GC/MS assay to determine the sterol contents of candidal albicandstreated by tetralin compounds. Interestingly, we found that three new sterols appearedand became the main peaks in gas chromatogram, with the amount of squalene,ergosterol, and lanosterol diminishing or disappear. This gas chromatogram result wasidentical with the one of erg24 mutants reported by JIA.N and hinted that the mechanismaction of tetralin compounds may affect on the ergoserol biosynthetic pathway andinhibit the function of sterol C-14 reductase, encoded by the ERG24 gene. Ourinvestigations provide scietific proofs and broad promising for drug development.