Abstract
A promising anti-Candida activity of Buchenavia tomentosa extracts was recently described. In the present work, experiments were carried out to determine the fraction with higher antifungal activity from a B. tomentosa extract. Acetone fraction (AF) was obtained from the aqueous extract from dried leaves (5 min/100°C) and it was the most effective one. Gallic acid (GA) was identified by electrospray ionization mass spectrometry (ESI–MS) and also chosen to perform antifungal tests due to its promising activity on Candida albicans. Minimal inhibitory and fungicidal concentrations (MIC and MFC) were determined by broth microdilution technique. The effect on virulence factors of C. albicans was evaluated, and the cytotoxicity was determined. MIC50 and MIC90 values were both equal to 0.625 mg ml-1 for AF and 2.5 and 5 mg ml-1, respectively, for GA. AF and GA showed ability to inhibit C. albicans adherence and to disrupt 48 h-biofilm. AF and GA were effective in reducing the formation of hyphae of C. albicans SC5314. AF and GA decreased adherence of C. albicans to oral epithelial cells. AF and GA showed slight to moderate toxicity to Vero cells. This result suggests further studies for topic use of these compounds. AF, which contains a combination of several molecules, presented greater potential of antimicrobial activity than GA, with lower values of MIC and lower cytoxicity.
Highlights
Candida belongs to a vast and heterogeneous genus, presenting more than 200 species (Williams et al, 2013)
The aims of this work were (i) to obtain different fractions of B. tomentosa leaves extracts and investigate their antifungal activity, (ii) to perform the chemical characterization of the most active fraction, (iii) to determine minimal inhibitory and fungicidal concentrations of this fraction, (iv) select one isolate compound with promising anti-candidal activity and determine inhibitory and fungicidal concentrations, and (v) to evaluate the effect of these antifungal agents on C. albicans virulence factors, determining their effect on biofilm formation and eradication, on the production of proteinase and phospholipase, on morphogenesis, and the in vitro activity on C. albicans adherence to oral epithelial cells
The inhibition halos for fractions varied between 9 and 11 mm
Summary
Candida belongs to a vast and heterogeneous genus, presenting more than 200 species (Williams et al, 2013). The genus Candida presents many species, only 20 are usually related to human infections (Williams et al, 2013), which range from superficial to systemic diseases. Superficial infectious, less harmful, are more frequent and can be recurrent for some. Systemic infections initiate when fungi invade the epithelial barrier and reach the blood circulation, causing candidemia (Gow et al, 2012). Candida albicans is usually the most frequently involved species in cases of candidemia (Arendrup, 2013; da Matta et al, 2017; Fu et al, 2017)
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