In Silico and In Vitro Evaluation of the Antifungal Activity of a New Chromone Derivative against Candida spp.

Candida species are frequently implicated in the development of both superficial and invasive fungal infections, which can impact vital organs. In the quest for novel strategies to combat fungal infections, there has been growing interest in exploring synthetic and semi-synthetic products, particularly chromone derivatives, renowned for their antimicrobial properties. In the analysis of the antifungal activity of the compound (E)-benzylidene-chroman-4-one against Candida, in silico and laboratory tests were performed to predict possible mechanisms of action pathways, and in vitro tests were performed to determine antifungal activity (MIC and MFC), to verify potential modes of action on the fungal cell membrane and wall, and to assess cytotoxicity in human keratinocytes. The tested compound exhibited predicted affinity for all fungal targets, with the highest predicted affinity observed for thymidylate synthase (-102.589 kJ/mol). MIC and CFM values ranged from 264.52 µM (62.5 µg/mL) to 4232.44 µM (1000 µg/mL). The antifungal effect likely occurs due to the action of the compound on the plasma membrane. Therefore, (E)-benzylidene-chroman-4-one showed fungicidal-like activity against Candida spp., possibly targeting the plasma membrane.

Breakpoints for the Classification of Anti-Candida Compounds in Antifungal Screening.

INTRODUCTION: The absence of a standardized classification scheme for the antifungal potency of compounds screened against Candida species may hinder the study of new drugs. This systematic review proposes a scheme of interpretative breakpoints for the minimum inhibitory concentration (MIC) of bioactive compounds against Candida species in in vitro tests. MATERIALS AND METHODS: A literature search was conducted in the PubMed, Scopus, Web of Science, Lilacs, and SciFinder databases for the period from January 2015 to April 2020. The following inclusion criterion was used: organic compounds tested by the microdilution technique according to the Clinical and Laboratory Standards Institute protocol against reference strains of the genus Candida. A total of 545 articles were retrieved after removing duplicates. Of these, 106 articles were selected after applying the exclusion criteria and were evaluated according to the number of synthesized molecules and their chemical classes, the type of strain (reference or clinical) used in the antifungal test, the Candida species, and the MIC (in µg/mL) used. RESULTS: The analysis was performed based on the median, quartiles (25% and 75%), maximum, and minimum values of four groups: all strains, ATCC strains, C. albicans strains, and C. albicans ATCC strains. The following breakpoints were proposed to define the categories: MIC < 3.515 µg/mL (very strong bioactivity); 3.516-25 µg/mL (strong bioactivity); 26-100 µg/mL (moderate bioactivity); 101-500 µg/mL (weak bioactivity); 500-2000 µg/mL (very weak bioactivity); and >2000 µg/mL (no bioactivity). CONCLUSIONS: A classification scheme of the antifungal potency of compounds against Candida species is proposed that can be used to identify the antifungal potential of new drug candidates.