Candida spp. are one of the most common fungal pathogens. Biofilms formed by Candidaalbicans offer resistance mechanisms against most antifungal agents. Therefore, development of new molecules effective against these microorganisms, alone or in combination with antifungal drugs, is extremely necessary. In the present work, we carried out a screening process of different cationic carbosilane dendritic molecules against C. albicans. In vitro activity against biofilm formation and biofilms was tested in both Colección Española de Cultivos Tipo (CECT) 1002 and clinical C. albicans strains. Cytotoxicity was studied in human cell lines, and biofilm alterations were observed by scanning electron microscopy (SEM). Antifungal activity of the carbosilane dendritic molecules was assessed by monitoring cell viability using both established and novel cell viability assays. One out of 14 dendritic molecules tested, named BDSQ024, showed the highest activity with a minimum biofilm inhibitory concentration (MBIC) for biofilm formation and a minimum biofilm damaging concentration (MBDC) for existing biofilm of 16–32 and 16 mg/L, respectively. Synergy with amphotericin (AmB) and caspofungin (CSF) at non-cytotoxic concentrations was found. Therefore, dendritic compounds are exciting new antifungals effective at preventing Candida biofilm formation and represent a potential novel therapeutic agent for treatment of C. albicans infection in combination with existing clinical antifungals.

SUMMARY: Amoebae were isolated from contact lenses of a symptomatic lens wearer in Spain. Protozoa were characterized by studying their morphology, biology, protease activity and the 18S rRNA gene sequence. Morphology of the organism was observed by light microscopy, scanning electron microscopy and transmission electron microscopy. Its structure corresponded to an amphizoic amoeba. The protozoa grew well at 37 °C and poorly at lower temperatures. In addition, it was capable of lysing mammalian cellsin vitro. A major 56 kDa proteolytic enzyme was observed in amoeba crude extracts by gelatin–sodium dodecyl sulphate–polyacrylamide gel electrophoresis. Most proteolytic enzymes in protozoa extracts showed significant activity over a wide range of pH (3–9) and temperature (8–45 °C) values. The assays on inhibition of protease activity indicated strongly that enzymes detected in amoeba extracts corresponded to serine proteases and, to a lesser extent, cysteine proteases. The use of proteinase inhibitors on a tissue culture model proved that the proteinase activity is critical for developing focal lesions in HeLa cell monolayers. Finally, partial sequencing of the 18S ribosomal RNA gene and phylogenetic analyses indicated that the isolate is closely related toAcanthamoeba griffiniH37 from the UK (T3 genotype).