Abstract Description

The inclusion of Cryptococcus neoformans (C. neoformans) in the World Health Organisation’s Fungal Priority Pathogen List signifies its importance as a pathogen. Part of the inclusion criteria was based on drug resistance, highlighting the need to find alternative treatment options. This paper considered the effects of a tincture derived from Usnea barbata as an anti-Cryptococcus therapeutic. The antifungal property of this tincture was determined by assessing the in vitro susceptibility profile of three C. neoformans strains using the EUCAST protocol. This was followed by characterising the phytochemicals present in the tincture. It was determined that the tincture displayed growth-inhibitory properties, although with variable sensitivity when considering the drug response profile of each tested strain. Phytochemical screening revealed the presence of tannins and flavonoids with phenols as the main bioactive constituents. The observed antifungal activity may be attributed to the well-documented properties of phenolic compounds, which contain usnic acid. This acid is the main biomolecule of Usnea barbata and has been shown to exhibit both antibacterial and antifungal activity. These results allow us to conclude that the Usnea barbata tincture can be used to limit the growth of cryptococcal cells. On the other hand, further studies involving more strains and a greater drug concentration gradient are required to establish breakpoints and establish the tincture’s mode of action.