Abstract Description

The sister sibling species Cryptococcus (C.) neoformans and C. gattii have emerged as priority fungal pathogens that often display non-fluconazole susceptibility. The latter necessitates the need to find alternative drugs that may be used to control the growth of cryptococcal cells. This paper explored using Gleditsia triacanthos as a potential source of antifungal phytochemical compounds. Phytochemicals were first extracted using dichloromethane (DCM), hexane, and methanol as solvents, followed by phytochemical profiling. In the end, the antifungal activity of the DCM, hexane, and methanol extracts against two C. neoformans strains and two C. gattii strains was assessed using an in vitro susceptibility assay based on the EUCAST protocol. DCM and hexane extracts contained terpenoids exclusively, while methanol extracts contained phenols, flavonoids (predominant), and tannins, but lacked terpenoids. All extracts exhibited growth inhibition, although with variable sensitivity when considering the drug response profile of each tested strain. The observed growth inhibition activity may be attributed to the phytochemical content. For example, the lipophilic terpenoids, found in the non-polar DCM and hexane fractions, are known to integrate into fungal membranes, destabilising them. The methanol extract activity can be attributed to its polar phytochemicals: phenols also destabilise membranes, flavonoids inhibit fungal efflux pumps, while tannins bind to fungal cell wall proteins, impairing growth. Collectively, these results show that distinct classes of phytochemicals extracted by different solvents contribute unique antifungal mechanisms, underlining the importance of extraction polarity in antifungal drug discovery. Future studies involving more strains are necessary to determine clinical breakpoints and to establish the mechanism of action for each extract.