Evaluation of Intestinal Permeability of the Antifungal Compound PD76: Comparison of in silico Platforms and in vitro Assay in Caco-2 Cell Model

The compound 2-hydrazinyl-4-(4-methoxyphenyl)thiazole (PD76) is a novel thiazolyl hydrazine derivative with proven antifungal activity against different fungal species, mainly Candida and Cryptococcus. Considering the advantages of oral route for clinical therapy, the aim of this work was to evaluate the potential intestinal permeability of this new antifungal drug. For the quantitation of PD76, a high-performance liquid chromatography method was developed and fully validated. The cytotoxicity of the compound in Caco-2 cells was analyzed and intestinal permeability of PD76 was assessed by means of the comparison of in vitro assay in Caco-2 cells and in silico platforms ADMETlab and admetSAR. Cell viability above 70% was obtained at all PD76 studied concentrations. Using Caco-2 cell model, the compound showed apparent permeability coefficients (Papp) of 5.25 x 10-6 and 23.28 x 10-6cm s-1 in apical-basolateral and basolateral-apical directions, respectively. Experiments performed using verapamil as P-gp inhibitor demonstrated that PD76 is slightly susceptible to active efflux. Both in silico platforms inferred that PD76 presents permeability in Caco-2 cells, with Log P values of 2.82 (ADMETlab) and 2.10 (admetSAR). The results obtained in permeability studies showed that PD76 presents moderate intestinal permeability and a promising profile for clinical application.