Unravelling novel molecular targets of Thymol and Carvacrol in Candida glabrata

The emergence of non-albicans Candida as a potential causative agent of candidiasis following Candida albicans is occurring globally. It is known that phenolic cresols, thymol, and carvacrol have anti-Candida characteristics. However, there are few papers that disclose the mechanism of action, which is characterized by a damaged cell wall and ergosterol synthesis, as well as calcium-induced death in C. albicans. This work utilized in-silico docking analysis to examine the molecular targets of thymol and carvacrol in Candida glabrata. The results were then validated in vitro by antifungal susceptibility testing and growth curve analysis. The study incorporated C. glabrata deletion mutants for the target proteins to gain understanding of the function of these proteins in the antifungal effects of the two monoterpenoids. After conducting molecular docking and in silico toxicity evaluations, thymol and carvacrol were chosen for in vitro investigations. Experimental tests conducted in a laboratory setting have shown that both phytocompounds exhibit strong binding affinity towards cell wall synthesis proteins (Kre1p, Kre2p, Ecm33p), calcium channel proteins (Mid1p, Ecm7p), and proteins involved in the ergosterol synthesis pathway (Erg5p). These proteins are likely to be the specific targets for the anti-Candida properties of the two isomeric monoterpenoids in C. glabrata. Minimum inhibitory concentration (MIC50) values for thymol and carvacrol range from 50 µg/ml to 75 µg/ml. The wild-type strains exhibit a minimum fungicidal concentration of 100 µg/ml for thymol and 125 µg/ml for carvacrol. The results underscore the significance of these proteins in the fungal reaction to thymol and carvacrol and also indicate a promising opportunity for the development of novel antifungal treatment methods utilizing these proteins.