Antifungal Activity of a Hydroethanolic Extract From Astronium urundeuva Leaves Against Candida albicans and Candida glabrata

Abstract

We have previously reported on the activity of different extracts from Astronium sp. against Candida albicans, with the hydroethanolic extract prepared from leaves of A. urundeuva, an arboreal species widely distributed in arid environments of South America and often used in folk medicine, displaying the highest in vitro activity. Here we have further evaluated the antifungal activity of this extract against strains of C. albicans and C. glabrata, the two most common etiological agents of candidiasis. The extract was tested alone and loaded into a nanostructured lipid system (10% oil phase, 10% surfactant and 80% aqueous phase, 0.5% Poloxamer 407®). In vitro susceptibility assays demonstrated the antifungal activity of the free extract and the microemulsion against both Candida species, with increased activity against C. glabrata, including collection strains and clinical isolates displaying different levels of resistance against the most common clinically used antifungal drugs. Checkerboard results showed synergism when the free extract was combined with amphotericin B against C. albicans. Serial passage experiments confirmed development of resistance to fluconazole but not to the free extract upon prolonged exposure. Although preformed biofilms were intrinsically resistant to treatment with the extract, it was able to inhibit biofilm formation by C. albicans at concentrations comparable to those inhibiting planktonic growth. Cytotoxicity assays in different cell lines as well as an alternative model using Artemia salina L. confirmed a good safety profile of the both free and loaded extracts, and an in vivo assay demonstrated the efficacy of the free and loaded extracts when used topically in a rat model of vaginal candidiasis. Overall, these results reveal the promise of the A. urundeuva leaves extract to be further investigated and developed as an antifungal.

Preliminary study on the synergistic interaction of Garcinia kola and Vernonia amygdalina against Candida albicans

“…Studies on the combined effects of plant extracts against C. albicans have proven to be more effective than when tested alone [4,30]. In this study, a combination of G. kola and V amygdalina was observed to produce a synergistic effect against C. albicans at all the combined ratios.…”

“…Over the years, researchers have sought alternative approaches in combating this problem. The search for plant based antifungal agents to tackle this menace has been on the increase probably due to their recorded improved effects over conventional antifungal agents [4,5]. Factors such as side effects, emergence of resistant strains, costs and availability have hindered wide utilization of some conventional antimicrobial drugs [6,7].…”

Antifungal activity of dendritic cell lysosomal proteins against Cryptococcus neoformans

“…One method is the use of a combination of compounds that, by themselves, display anti-cryptococcal properties, such as current guidelines that advise treating cryptococcal meningitis using combination therapy with AmpB and flucytosine 56 . Therefore, we tested our anti-cryptococcal lysosomal proteins in combination with AmpB against the fully virulent C. neoformans strain H99 using a checkerboard method and categorized data based on the fractional inhibitory concentration indices (FICI) 57 . While still retaining their previously stated anti-cryptococcal capacity, none of the lysosomal proteins showed any synergistic effects when used in combination with AmpB (Supplemental Table S2 ).…”

“…Anti-cryptococcal activity of AmpB in combination with anti-cryptococcal lysosomal proteins was measured in vitro using a checkerboard method as previously described 57 . Assays were conducted in either phosphate buffer (pH 5.5) or RPMI-MOPS (pH 7.0) (both described above) in 100 µl total.…”

Antifungal and Antibiofilm Activities of B-Type Oligomeric Procyanidins From Commiphora leptophloeos Used Alone or in Combination With Fluconazole Against Candida spp.

“…However, complex changes in microbial communities may cause various disorders, such as opportunistic fungal infections ( Zelante et al, 2020 ). Candidiasis is the name given to a broad range of infections caused by the Candida species ( Bonifácio et al, 2019 ). It is worth noting that Candida spp.…”