Comparison of a glucose consumption based method with the CLSI M38-A method for testing antifungal susceptibility of Trichophyton rubrum and Trichophyton mentagrophytes

Background The prevalence of dermatophytoses and the development of new antifungal agents has focused interest on susceptibility tests of dermatophytes. The method used universally for susceptibility tests of dermatophytes was published as document （M38-A） in 2002 by the Clinical and Laboratory Standards Institute （CLSI）, dealing with the standardization of susceptibility tests in filamentous fungi, though not including dermatophytes especially. However, it is not a very practical method for the clinical laboratory in routine susceptibility testing. In this test, we developed a novel rapid susceptibility assay --glucose consumption method （GCM） for dermatophytes. Methods In this study, we investigated the antifungal susceptibilities of dermatophytes to itraconazole （ITC）, voriconazole （VOC）, econazole nitrate （ECN） and terbinafine （TBF） by glucose consumption method （GCM）, in comparison to the Clinical and Laboratory Standards Institute （CLSI） M38-A method. Twenty-eight dermatophyte isolates, including Trichophyton rubrum （T. rubrum） （n=-14） and Trichophyton mentagrophytes （T. mentagrophytes） （n=-14）, were tested. In the GCM, the minimum inhibitory concentrations （MICs） were determined spectrophotometrically at 490 nm after addition of enzyme substrate color mix. For the CLSI method, the MICs were determined visually. Results Comparison revealed best agreement for TBF against T. mentagrophytes and T. rubrum, since MIC range, MIC50, and MIC90 were identical from two methods. However, for ITC and VOC, GCM showed wider MIC ranges and higher MICs than CLSI methods in most isolates. For ECN against T. rubrum, high MICs were tested by GCM （0.125-16 pg/ml） but not M38-A method （0.5-1 IJg/ml）. The overall agreements for all isolates between the two methods within one dilution and two dilutions for ITC, VOC, ECN and TBF was 53.6% and 75.0%, 57.1% and 75.0%, 82.1% and 89.3%, and 85.7 and 85.7%, respectively. Conclusion Measurement of glucose uptake can predict the susceptibility of T. rubrum and T. mentagrophytes to ECN and TBF.

An in vitro and in silico study of anti-dermatophytic activity of gossypol from fruits of Thespesia populnea(L.)Sol.ex Correa

Objective:To isolate,purify,and characterize gossypol from the fruits of Thespesia populnea(L)Sol.ex Correa,test its antidermatophytic activity,identify its targets on the dermatophyte,and confirm the binding of gossypol with the fungal target by molecular docking study.Methods:Gossypol from Thespesia populnea was characterized by high performance liquid chromatography,liquid chromatographmass spectrometry,Fourier transform infrared spectroscopy,and nuclear magnetic resonance.The anti-dermatophytic activity of gossypol was tested against four different dermatophytes,viz.Trichophyton mentagrophytes,Trichophyton rubrum,Microsporum canis,and Microsporum gypseum.Trichophyton mentagrophytes was selected for further studies.The inhibitory mode of action of gossypol on Trichophyton mentagrophytes was determined by analyzing the modulation of gene expression in various pathways of the dermatophyte.Results:Gossypol inhibited all the dermatophytes.The minimum inhibitory concentrations were 12.5μg/mL for Trichophyton mentagrophytes and Microsporum canis and 25μg/mL for Trichophyton rubrum and Microsporum gypseum.The minimum fungicidal concentrations were 50μg/mL for Trichophyton mentagrophytes,100μg/mL for Microsporum canis and Trichophyton rubrum,and 200μg/mL for Microsporum gypseum.Gossypol inhibited the mRNA expression of metalloprotease(MEP4)and isocitrate lyase(ICL).The binding of gossypol with the enzymes was confirmed by molecular docking studies.The best docking poses were found and the low binding energies were recorded with the two target enzymes.Conclusions:Gossypol is a potential antifungal agent and can be further explored as an anti-dermatophytic drug.

Synthesis, characterization,thermal behavior,and antifungal activity of La(Ⅲ) complexes with cinnamates and 4-methoxyphenylacetate

In this study a series of trivalent lanthanum complexes with 4-（R）-cinnamate （4-Rcinn, R=H（1）, MeO（2）, Cl（3）） and 4-methoxyphenylacetate ligands （4） were prepared and their antifungal activity against Candida albicans, Aspergillus niger and Trichophyton mentagrophytes were examined. Compounds 1-4 were synthesized by a metathesis reaction and fully characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, fluorescence spectra, thermogravimetry （TG）, derivative thermogravimetry （DTG）, differential scanning calorimetry （DSC） and X-ray diffraction powder patterns. In emission studies, it was observed that lu-minescence intensity was enhanced in the presence of lanthanide ion. The results of X-ray diffraction patterns indicated that all com-plexes studied exhibited crystalline structure. Thermal behavior by TG, DTG, and DSC studies permitted to estimating the hydration degree of the compounds and showed the formation of decomposition products like lanthanum oxide. Determined by antifungal stud-ies, lanthanum complexes 1-4 demonstrated antifungal activity toward all pathogenic fungal strains tested. Compounds 2 and 4 showed significant growth inhibition for A. niger and C. albicans, respectively.