In vitro activity of ethanolic extract of propolis (EEP) against Candida albicans pathogenicity mechanisms
Authors:   Department of Forensic Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai Province, Thailand., Khacha-ananda Supakit , Thammasit Patcharin ,   Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai Province, Thailand., Iadnut Anupon ,   Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla Province, Thailand, Sangboonruang Sirikwan ,   Office of Research Administration, Chiang Mai University, Chiang Mai Province, Thailand., Division of Clinical Microbiology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai Province, Thailand., Tragoolpua Yingmanee ,   Department of Biology, Faculty of Sciences, Chiang Mai University, Chiang Mai Province, Thailand., Tragoolpua Khajornsak ,   Division of Clinical Microbiology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai Province, Thailand
Published: January 2025

Background: Candidiasis is an opportunistic fungal infection mainly caused by an overgrowth of Candida albicans. Several virulence factors, including the ability to change its morphology from yeast to hyphae and the secretion of hydrolytic enzymes, contribute to and promote the pathogenesis of the disease.

Objective: We aimed to investigate the efficacy of ethanolic extract of propolis (EEP) on growth and some major virulence factors of C. albicans that involved pathogenesis development, such as adhesion, hyphal germination, invasion, and virulence enzyme activities.

Materials and methods: C. albicans DMST 21424 was treated with various concentrations of EEP, and the growth of yeast cells was determined by colonyforming unit assay. An investigation of morpho-transformation ability was carried out using a hyphal germination assay and a hyphal length measurement. The adhesion ability of EEP-treated yeast cells was determined on both abiotic and biotic materials using acrylic discs and HeLa cell surfaces, respectively. The infected cells were treated with EEP to study invasion ability, and the cell damage was indicated by lactate dehydrogenase (LDH) activity assay. The effect of EEP on virulence enzyme activity was evaluated on sheep blood agar for hemolysin, egg yolk agar for phospholipase, and bovine serum albumin (BSA) agar for proteinase. Then, the mRNA expression levels of virulence enzyme-related genes such as ALS1, SAP1, SAP2, SAP3, and SAP6 were assessed by quantitative reverse transcriptase polymerase chain reaction (RT-PCR).

Results: The growth of EEP-treated yeasts was suppressed in a dose-dependent manner. The yeast-to-hyphae transition property was significantly reduced in EEP-treated yeast. EEP treatment also significantly decreased adhesion, invasion, and proteinase activity. However, there was no difference in hemolysin and phospholipase activities between EEP-treated yeast and the control. Moreover, EEP also remarkably down-regulated agglutinin-like-sequence 1 (ALS1) and secreted aspartyl proteinase (SAPs) genes.

Conclusion: The findings revealed that EEP exhibited potent anti-C. albicans virulence factors associated with pathogenesis. Therefore, this study suggested that propolis might be an effective complementary medicine alternative for candidiasis treatment.