Abstract
Oral candidiasis is one of the most common fungal infections in humans. Its incidence has increased widely, as well as the antifungal resistance, demanding for the search for novel antifungal therapeutic agents. Anadenanthera colubrina (Vell.) Brenan is a plant species that has been proven to possess pharmacological effects, including antifungal and anti-inflammatory activities. This study evaluated in vitro the effects of standardized A. colubrina extract on virulence factors of Candida albicans and its regulation on immune response through C. albicans-host interaction. Antifungal activity was evaluated by Broth Microdilution Method against reference Candida strains (C. albicans, C. glabrata, C. tropicalis; C. dubliniensis). Anti-biofilm effect was performed on C. albicans mature biofilm and quantified by CFU/mL/g of biofilm dry weight. Proleotlytic enzymatic activities of proteinase and phospholipase were assessed by Azocasein and Phosphatidylcholine assays, respectively. Cytotoxicity effect was determined by Cell Titer Blue Viability Assay on Human Gingival Fibroblasts. Co-cultured model was used to analyze C. albicans coexisting with HGF by Scanning Electron Microscopy and fluorescence microscopies; gene expression was assessed by RT-PCR of C. albicans enzymes (SAP-1, PLB-1) and of host inflammatory cytokines (IL-6, IL-8, IL-1β, IL-10). Cytokines secretion was analysed by Luminex. The extract presented antifungal effect with MIC<15.62 μg/ml against Candida strains. Biofilm and proteolytic activity were significant reduced at 312.4 μg/ml (20 × 15.62 μg/ml) extract concentration. Cell viability was maintained higher than 70% in concentrations up to 250 μg/ml (LD50 = 423.3 μg/ml). Co-culture microscopies demonstrated a substantial decreased in C. albicans growth and minimal toxicity against host cells. Gene expressions of SAP-1/PLB-1 were significantly down-regulated and host immune response was modulated by a significant decreased on IL-6 and IL-8 cytokines secretion. A. colubrina had antifungal activity on Candida strains, antibiofilm, and anti-proteolytic enzyme effects against C. albicans. Presented low cytotoxicity to the host cells and modulatory effects on the host immune response.
Highlights
Oral candidiasis is one of the most common fungal infections in humans (Hertel et al, 2016; Rosa-García et al, 2020) and is caused by yeasts from the genus Candida (Williams and Lewis, 2011), a polymorphic fungus and a commensal microorganism that colonizes the human oral cavity in healthy people (Nikou et al, 2019)
We evaluated the A. colubrina extract effects on virulence factor of C. albicans and its modulatory effects on host immune response during the fungal infection
We evaluated the phytochemical composition of the A. colubrina extract (Lima et al, 2014), in which was found that the extract presents in its composition a high total polyphenol content (53.18% gallic acid equivalents); tannins (8.77% catechin equivalents) and flavonoids (0.28% quercetin equivalents)
Summary
Oral candidiasis is one of the most common fungal infections in humans (Hertel et al, 2016; Rosa-García et al, 2020) and is caused by yeasts from the genus Candida (Williams and Lewis, 2011), a polymorphic fungus and a commensal microorganism that colonizes the human oral cavity in healthy people (Nikou et al, 2019). Considering the continuing rise of resistant Candida spp. strains and the limited number of antifungal agents, novel therapeutic strategies have been directed toward the identification of bioactive compounds that target virulence factors and pathogenic mechanisms to prevent C. albicans transition from harmless commensal to pathogen (Francisconi et al, 2020; Vila et al, 2020). In this regard, natural products from plants are considered a potential source for the development of new antifungal therapies. Recent researches have shown that A. colubrina has promising therapeutic properties, such as antifungal (Lima et al, 2014; Silva et al, 2019), anti-proliferative (Lima et al, 2014), antiinflammatory (Guarneire et al, 2019; Cardoso-Junior et al, 2020), antioxidant (Araújo et al, 2019; Cardoso-Junior et al, 2020), and anti-HIV (Maia et al, 2021)
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