Small-molecule inhibitors of biofilm formation in laboratory and clinical isolates of Candida albicans

Abstract

Candida albicans cells have the ability to form biofilms on biotic and abiotic surfaces, such as indwelling medical devices. C. albicans cells can interconvert between budded and hyphal growth forms, herein termed the budded-to-hyphal transition (BHT), which is important for the formation of mature biofilms. Previous work identified 23 small organic molecules that could inhibit the BHT but did not affect C. albicans cell viability or budded cell growth. These BHT inhibitors were proposed to inhibit multiple signalling pathways regulating the BHT, many of which also regulate biofilm formation. However, only three of the BHT inhibitors, buhytrinA, ETYA and CGP-37157, were capable of inhibiting in vitro biofilm formation of wild-type laboratory C. albicans strains. When clinical C. albicans isolates were examined for their ability to form biofilms, only 11 of the 28 clinical isolates tested (39 %) were capable of forming biofilms. Although buhytrinA, ETYA and CGP-37157 could inhibit the BHT of all 28 clinical isolates, they were only able to inhibit biofilm formation of a subset of these clinical isolates, with ETYA having 100 % efficacy. These data indicate that the biofilm-forming capability of laboratory and clinical isolates of C. albicans, as well as the efficacy of BHT inhibitors against these different isolates, can differ dramatically. These differences between laboratory and clinical isolates should be an important aspect to consider when examining potentially new antifungal therapeutics.

From Biology to Drug Development: New Approaches to Combat the Threat of Fungal Biofilms

“…More recently, and using similar HTS techniques, this same group identified 2-adamantanamine (AC17) as a chemosensitizer and potentiator of another azole antifungal, miconazole (60). The Johnson group screened for inhibitors of the budded-to-hyphal-form transition in C. albicans ; the identified inhibitors likely inhibit multiple signalling pathways involved in filamentation, many of which also regulate biofilm formation (61, 62). They subsequently reported that three of these inhibitors, buhytrinA, ETYA and CGP-37157, were capable of inhibiting C. albicans biofilm formation, although the biofilm-inhibitory activity varied among different clinical isolates (62).…”

Minocycline Inhibits <i>Candida albicans</i> Budded-to-Hyphal-Form Transition and Biofilm Formation

“…Several inhibitors of hyphal formation and biofilm formation by C. albicans have already been reported, including buhytrin A, ETYA, and CGP-37157 (8). Nonetheless, their structures do not provide insights into their potential activity.…”

“…Biofilm formation by C. albicans involves a budded-to-hyphal-form transition (BHT). Toenjes et al found that 23 small molecules inhibit C. albicans BHT (6,7) and subsequently identified 3 compounds that are effective against C. albicans biofilm formation: buhytrin A, ETYA, and CGP-37157 (8).…”

In Vitro Analysis of Finasteride Activity against Candida albicans Urinary Biofilm Formation and Filamentation

“…FLC indirectly inhibits ergosterol synthesis by the inhibition of microsomal cytochrome P450, whereas AMB interacts directly with ergosterol in the plasma membrane. Additionally, recent publications (37)(38)(39)(40)(41)(42) have suggested that the antifungal activity of AMB might also be mediated by oxidative damage. …”