Antifungal activity of stingless bee Melipona beecheii honey against Candida albicans and its effects on virulence gene expression

Infections related to Candida genus have increased around the world, this is caused by development of antifungal resistance in clinical strains, complications are arising due to changes on human microbiota and immunosuppressive regimes related to organ transplantations1. The use of natural compounds present in plants and bacteria is an attractive alternative to commercial antifungals. In this sense, honey has been used since ancient times to treat skin disorders and infections2. The objective of this work was to determine the antifungal effect of M. beecheii honey on Candida albicans ATCC 10231 strain. This honey has a long tradition in the folklore medicine against several human diseases such as gastrointestinal and skin disorders. We determined that 20 % (v/v) of honey is able to reduce more than 80 % of growth culture in liquid media and notably, concentrations of 35 % (v/v) and above are able to inhibit completely the growth of this pathogen. Based on these results, we concluded that Melipona honey has antifungal effects against C. albicans. Subsequently, we performed qRT-PCR in order to determine the effect of sub-lethal concentrations on genetic expression of virulence factors, as a result we demonstrated that relatively low concentrations of 12 % (v/v) of stingless bee honey reduced the levels of expression of two virulence genes sap6 (secreted aspartyl protease) and hwp1 (hyphal wall protein) using act1 (actin) gene as reference. Hence, results indicated that honey from M. beecheii could be a natural source of novel antifungal compounds.

1Morschhäuser, J. (2016). The development of fluconazole resistance in Candida albicans–an example of microevolution of a fungal pathogen. Journal of Microbiology, 54(3), 192-201.

2Ortiz-Vazquez, E., Cuevas-Glory, L., Zapata-Baas, G., Martinez-Guevara, J., & Ramon-Sierra, J. (2013). Which bee honey components contribute to its antimicrobial activity? A review. African Journal of Microbiology Research, 7(51), 5758-5765.