Abstract Few antifungals available today are effective in treating biofilms. Thus, it is urgent to discover new compounds, such as natural products, that provide improvements to existing treatments or the development of new antifungal therapies. This study aimed to perform a comparative analysis between the green propolis extract (PE) and its by-product, a waste of propolis extract (WPE) through a screening with Candida sp., Fusarium sp. and Trichophyton sp. The antifungal property of PE and WPE was assessed by the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) determination in planktonic cells. The influence of both extracts on the inhibition of biofilm formation in these fungi was also tested. The WPE MIC and MFC values (68.75 to 275.0 µg/mL) were three to twelve times lower than the values obtained for PE (214.06 to 1712.5 µg/mL). PE was more efficient than WPE in inhibiting the biofilm initial phase, especially in C. albicans. Meanwhile, WPE had dose-dependent behavior for the three fungi, being more effective on filamentous ones. Both PE and WPE showed excellent antifungal activity on planktonic cells and demonstrated great efficacy for inhibiting biofilm formation in the three fungi evaluated.

Abstract Biofilms are important to the virulence of human pathogenic fungi, and some molecules have been found to play key roles in the growth and regulation of fungal biofilms. Farnesol, one of these molecules, is well-described for some microorganisms but is still scarcely known for Rhodotorula spp. This study aimed to evaluate the influence of farnesol on the biofilm of R. mucilaginosa. Initially, screening with 0.2 mM to 2.1 mM of farnesol was evaluated against planktonic forms. A concentration of this compound was then chosen and evaluated for its effect on biofilm in formation and on preformed biofilm after 24, 48 and 72 hours. The impact of farnesol was evaluated by colony-forming units (CFU) counts, determination of metabolic activity and quantification of total biomass. In the presence of 0.9 mM, farnesol was able to decrease the CFU number, at 48 hours, when the biofilm was in formation, although it did not affect the preformed biofilms. Thus, our results show that farnesol exerts a modulating activity during biofilm formation for R. mucilaginosa, with this compound reducing the metabolic activity and total biomass of the biofilms.

Extratos do pericarpo de frutos de Sapindus saponaria L. (Sapindaceae) foram testados para a atividade antifúngica sobre isolados clínicos de leveduras de Candida albicans e C. não-albicans obtidos de secreção vaginal de mulheres com Candidíase Vulvovaginal. Foram avaliados quatro isolados clínicos de C. albicans, um de cada uma das espécies C. glabrata, C. parapsilosis, C. tropicalis e uma cepa referência de C. albicans ATCC 90028. O extrato hidroalcoólico foi biomonitorado contra um isolado clínico de C. parapsilosis, apresentando forte atividade. O extrato butanólico e uma fração apresentaram forte atividade contra todos os isolados testados. Posterior análise desta fração via cromatografia em sílica gel (CHCl3:CH3OH, 1:1, v/v) resultou no isolamento de duas saponinas triterpênicas puras mono e diacetiladas, 3-O-(4-O-acetil-O-beta-D-xilopiranosil)-(1 -> 3)-alfa-L-ramnopiranosil-(1 -> 2)-alfa-L-arabinopiranosil-hederagenina (1) e 3-O-(3,4-di-O-acetil-beta-D-xilopiranosil)-(1 -> 3)-alfa-L-ramnopiranosil-(1 -> 2)-alfa-L-rabinopiranosil-hederagenina (2) respectivamente. A elucidação estrutural das substâncias foi baseada em dados espectrais (RMN de ¹H e de 13C, HSQC, HMBC, ESI/MS) e comparados com dados da literatura. As saponinas triterpênicas isoladas (1) e (2) apresentaram forte atividade contra C. parapsilosis.

Extracts from the dried pericarp of Sapindus saponaria L. (Sapindaceae) fruits were investigated for their antifungal activity against clinical isolates of yeasts Candida albicans and C. non-albicans from vaginal secretions of women with Vulvovaginal Candidiasis. Four clinical isolates of C. albicans, a single clinical isolated of each of the species C. parapsilosis, C. glabrata, C. tropicalis, and the strain of C. albicans ATCC 90028 were used. The hydroalcoholic extract was bioactivity-directed against a clinical isolate of C. parapsilosis, and showed strong activity. The n-BuOH extract and one fraction showed strong activity against all isolates tested. Further column-chromatography on silica gel separation of this fraction afforded two pure triterpene acetylated saponins: 3-O-(4-acetyl-beta-D-xylopyranosyl)-(1->3)-alpha-Lrhamnopyranosyl-(1->2)-alpha-L-arabinopyranosyl-hederagenin (1) and 3-O-(3,4-di-acetyl-beta-D-xylopyranosyl)-(1->3)-alpha-L-rhamnopyranosyl-(1->2)-alpha-L-arabynopyranosyl-hederagenin (2). The structures of the compounds were based on spectral data (¹H and 13C NMR, HSQC, HMBC and MS), and on with literature. The saponins isolated showed strong activity against C. parapsilosis.