Antifungal Activity, Mode of Action, and Cytotoxicity of 4-Chlorobenzyl p-Coumarate: A Promising New Molecule.

Fungal infections represent a serious health problem worldwide. The study evaluated the antifungal activity of 4-chlorobenzyl p-coumarate, an unprecedented semi-synthetic molecule. Docking molecular and assay experiments were conducted to determine the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC), mode of action, effect on growth, fungal death kinetics, drug association, effects on biofilm, micromorphology, and against human keratinocytes. The investigation included 16 strains of Candida spp, including C. albicans, C. krusei, C. glabrata, C. tropicalis, C. dubliniensis, C. lusitaniae, C. utilis, C. rugosa, C. guilhermondi, and C. parapsilosis. Docking analysis predicted affinity between the molecule and all tested targets. MIC and MFC values ranged from 3.9 µg/mL (13.54 µM) to 62.5 µg/mL (217.01 µM), indicating a probable effect on the plasma membrane. The molecule inhibited growth from the first hour of testing. Association with nystatin proved to be indifferent. All concentrations of the molecule reduced fungal biofilm. The compound altered fungal micromorphology. The tested compound exhibited an IC50 of 7.90±0.40 µg/mL (27.45±1.42 µM) for keratinocytes. 4-chlorobenzyl p-coumarate showed strong fungicidal effects, likely through its action on the plasma membrane and alteration of fungal micromorphology, and mildly cytotoxic to human keratinocytes.

α-Pinene: Docking Study, Cytotoxicity, Mechanism of Action, and Anti-Biofilm Effect against Candida albicans.

Candida albicans is associated with serious infections in immunocompromised patients. Terpenes are natural-product derivatives, widely studied as antifungal alternatives. In a previous study reported by our group, the antifungal activity of α-pinene against C. albicans was verified; α-pinene presented an MIC between 128-512 µg/mL. In this study, we evaluate time-kill, a mechanism of action using in silico and in vitro tests, anti-biofilm activity against the Candida albicans, and toxicity against human cells (HaCaT). Results from the molecular-docking simulation demonstrated that thymidylate synthase (-52 kcal mol-1), and δ-14-sterol reductase (-44 kcal mol-1) presented the best interactions. Our in vitro results suggest that α-pinene's antifungal activity involves binding to ergosterol in the cellular membrane. In the time-kill assay, the antifungal activity was not time-dependent, and also inhibited biofilm formation, while rupturing up to 88% of existing biofilm. It was non-cytotoxic to human keratinocytes. Our study supports α-pinene as a candidate to treat fungal infections caused by C. albicans.