## 4 Therapeutic Effects of Honey
### Antifungal Effects  
In addition to its antibacterial properties, honey also exhibits antifungal activity. Fungi are taught to be more pathogenic than bacteria, and therefore their resistance to antifungal drugs is more complex and requires new treatment approaches. Recently, the shift towards natural products and their promising antifungal effects has gained more attention, with honey being considered a viable solution in this regard [171].  
As shown in the previous chapters, the large variance of therapeutic effects of honey is due to both its physicochemical characteristics and biological compounds. Several studies have reported that the high sugar content can act as an inhibitor of fungi growth through the osmotic pressure [172]. Moreover, the variety of other substances contained in honey, namely phenolic compounds, play a key role in its antifungal effects [173]. These compounds have the ability to denature proteins and therefore the membranes of cells through the alteration of their stability [174]. It is well-known that the phenolic composition of each honey type depends on the botanical and geographical origin of collected plants, and thus various honey types can have a different outcome when it comes to antibacterial and antifungal properties [175; 176]. Indeed, [PERSON] et al. (2019) [177] reported that the presence of gallic acid and quercetin in different Saudi honey samples proved to have antifungal effects by inhibiting _Candida albicans (C. albicans)_ strains. Moreover, in this same study, the free acidity content was correlated with the highest _Candida_ inhibition effect, thus highlighting the importance of acids in influencing the antifungal effect of honey.  
Another study emphasised the antifungal activity of Manuka honey, stating that its chemical composition, mainly the presence of polyphenols such as gallic acid, caffeic acid, and quercetin, has a strong resistance to fungal strains [178]. These data were in accordance with other reports that have evaluated the antifungal activity of Manuka honey, where its main component, namely methylglyoxal, was predomenantly responsible for the high inhibition of fungal strains [172; 177; 148]. [PERSON] (2020) [179] presented the results of various Portuguese honeys (Chestnut, Eucalyptus, Orange Blossom, Rosemary and Heather) against several pathogens (clinical isolates and reference strains of _Candida_ species). It was concluded that among all honey samples, Portuguese heather honey had the higher phenolic and flavonoids content and thus exhibited the higher antifungal activity against the tested microorganisms. Furthermore, this variety of honey is considered to be a biofilm reducer for _Candida_ species at concentrations that range between 50% and 75% (\(w/v\)). Further relevant academic work has suggested that the production of H\({}_{2}\)O\({}_{2}\) is critical for the antifungal activity of honey, but still not sufficient, as its level in honey's composition was too low to manifest a potent activity against some pathogenic fungi [180]. This can lead us to the conclusion that there are other compounds that act may as enhancing factors for the observed antifungal activity. This notwithstanding, it was demonstrated that the inhibition degree on several pathogenic microorganisms depends on various honey concentrations, as observed in Tualang, Acacia and Kelbut honey against _C. albicans_ and _Aspergillus niger_ (5-25% \(v/v\)) [181]. In general, the outcomes suggest that the antifungal effects are intensified with an increased honey concentration [176; 182]. It is important to note that recent advances in research showed how medical-grade honey could be considered a promising alternative for antifungal treatment against _Candida auris_ and other _Candida_ species [183].