Extraction des composés actifs anti-Candida albicans d’une souche d’Actinomycetota et étude de leurs stabilités

Abstract

The objective of this study is to extract the active compounds produced by the Actinomycetota S18 strain, which exhibits inhibitory activity against the pathogenic yeast Candida albicans, and to evaluate the stability of these compounds under various physicochemical conditions. Morphological, particularly micromorphological, analysis suggested that this strain may belong to the genus Streptomyces. The kinetics of active metabolite production, evaluated using the well diffusion method on ISP2 and Bennett liquid media, indicated that the seventh day of incubation corresponds to the maximum antifungal activity against Candida albicans (C. albicans S1) as well as the reference strain Candida albicans ATCC 10231. Extraction of these metabolites using solvents of different polarities (dichloromethane and butanol) revealed that butanol was the only solvent capable of extracting these compounds, with inhibition zones measuring 15 mm against C. albicans S1 and 14 mm against C. albicans ATCC 10231. The stability study of the active compounds showed that they remained stable at pH 5 and 9, at a temperature of 50°C, and under light exposure, although with reduced activity compared to the control. Semi-purification of the butanolic extract was performed using thin-layer chromatography (TLC) with two solvent systems. The first system, AM (ethyl acetate: methanol at 100:15, v/v), allowed the detection of a single active spot by bioautography against C. albicans S1 with an Rf of 0.41, previously visualized under UV light at 365 nm as a green fluorescence. The second system, BAE (butanol, acetic acid: water at 4:3:3, v/v/v), also revealed a single active spot against CaS1 with an Rf of 0.55, visualized under UV light at 365 nm as a yellow fluorescence.