Honey has been recognized worldwide for its antioxidant, anti-tumor, anti-inflammatory and antimicrobial properties. Among them, the antifungal properties associated to honey make it an attractive alternative treatment for Candida-associated infections, particularly for topical application to the mucous membranes and skin. In this sense, the main purpose of this work was to evaluate physicochemical properties of five Portuguese honeys and Manuka honey (an Australian honey with well recognized medical proprieties, used as control) and to evaluate the antifungal activity in Candida species planktonic and biofilm assays. Pollen analysis, pH determination, color, concentration of protein and methylglyoxal, conductivity, total phenolics and flavonoids, hydrogen peroxide concentration, and characterization by differential scanning calorimetry in honey samples were determined. Additionally, the effect of honeys on planktonic growth of Candida was initially evaluated by determination of the minimum inhibitory concentrations. Then, the same effect of those honeys was evaluated in biofilms, by Colony Forming Units enumeration. It has been shown that Portuguese heather (Erica cinereal) honey presented the most similar physicochemical properties to manuka honey (specially phenolic and flavonoids contents). The five Portuguese honeys under study, presented in general a potent activity against planktonic multi-resistant yeast pathogens (several clinical isolates and reference strains of Candida species) and S. aureus and P. aeruginosa bacteria cultures. Additionally, it was also concluded that Portuguese heather honey (50% and 75% (w/v)) can also act as a good Candida species biofilm reducer, namely for C. tropicalis.

Candida auris is a recently found Candida species, mainly associated with nosocomial outbreaks in intensive care hospital settings, and unlike other Candida species, it can be transmitted through person-to-person or by contact with surfaces. C. auris is described as resistant to first-line antifungals and, consequently, associated with high mortality. Nowadays, essential oils (EOs) are known to be effective against fungal and bacterial infections. This work aimed to evaluate the effect of four EOs (tea tree, niaouli, white thyme and cajeput) against C. auris. The EO’s effect on C. auris planktonic growth was evaluated by the minimum inhibitory concentration determination and by the agar disc diffusion method. Then, the same effect was evaluated on biofilm by colony-forming units’ enumeration. The results showed that EOs were able to inhibit the C. auris planktonic growth, with an MIC50 between 0.78 and 1.56% and halos of 20–21 mm for white thyme and tea tree and 13–14 mm for cajeput and niaouli. In addition, the EOs were also able to completely inhibit biofilm formation. Moreover, white thyme and cajeput completely eradicate pre-formed biofilms, while tea tree and niaouli significantly reduce it. Thus, this work demonstrates that EOs are a possible therapeutic alternative and a future perspective for the hard fight against C. auris.

Fungal contaminations with Candida species are commonly responsible for several infections, especially when associated to bacteria. The therapeutic approach commonly used is being compromised due to microbial resistances of these microorganisms to antimicrobial agents, especially in biofilm. The use of honey as an antimicrobial agent has been emerging as a valuable solution and proving its potential in planktonic and in biofilm cells. This work aims to assess the effect of different honeys on biofilms of Candida tropicalis and Pseudomonas aeruginosa. The effect of Portuguese heather (PH) and manuka honeys on planktonic growth of Candida was initially evaluated by determination of the minimum inhibitory concentrations (MIC). Then, the same effect was evaluated in mixed biofilms, by colony-forming units numeration and fluorescence microscopy. The combinations of honey plus fluconazole and gentamicin were also tested. The results showed that the honeys tested enabled a great reduction of C. tropicalis, both in planktonic (12.5% and 25% of MIC for PH and manuka) and in biofilm. In polymicrobial biofilms, the use of PH and manuka honeys was revealed to be a promising choice and an alternative treatment, since they were able to reduce cells from both species. No synergistic effect was observed in antimicrobial combinations assays against polymicrobial biofilms.

Background: Vulvovaginal candidiasis (VVC) is a disease with high incidence, a huge impact on the quality of life and health of women, and which represents a great challenge to treat. The growing need to apply antifungal intensive therapies have contributed to an emergence of drug-resistant Candida strains. Thus, effective therapeutic options, to meet the antifungal-resistance challenge and to control high resilient biofilms, are urgently needed. This study aimed to investigate the antifungal activity of essentials oils (EOs) on drug-resistant Candida vaginal isolates. Method: Therefore, the antimicrobial effect of tea tree, niaouli, white thyme, and cajeput EOs on the planktonic growth of Candida isolates was initially evaluated by an agar disc diffusion method. Then, the vapor-phase effect of tea tree EO (VP-TTEO) on biofilm formation and on pre-formed biofilms was evaluated by crystal violet staining, XTT reduction assay, colony forming units’ enumeration, and scanning electron microscopy. Results: The results revealed high antifungal activity of EOs against drug-resistant Candida isolates. Additionally, the VP-TTEO showed a significant inhibitory effect on the biofilm formation of all tested isolates and was able to provoke an expressive reduction in mature Candida albicans biofilms. Conclusions: Overall, this study suggests that the VP-EO may be a promising solution that is able to prevent biofilm-related VVC caused by antifungal-resistant strains.

Recurrent vulvovaginal candidiasis (RVVC), predominantly caused by Candida albicans, represents a global health issue, particularly in developing regions. This study explores the antifungal potential of aqueous leaf extract of Schinus weinmanniifolia Mart. ex Engl., a native Latin American plant. The extract was evaluated for phytochemical composition, antifungal efficacy, and safety profile. Phytochemical analyses identified six major compounds, including shikimic acid, gallic acid, and methyl gallate, with antioxidant and antimicrobial properties. The extract showed potent antioxidant activity, with IC₅₀ values between 1.52–5.51 µg/mL. It strongly inhibited C. albicans, with a minimum inhibitory concentration (MIC) of 1.95 µg/mL, and was active against other yeasts (MIC 0.48–62.5 µg/mL). The growth kinetics assay revealed reduced C. albicans viability after 12 h at 2 × MIC versus the positive control. Scanning electron microscopy confirmed reduced fungal counts without morphological damage. The extract impaired C. albicans virulence, reducing germ tube formation by 75.49% and hyphal transition by 84.34%, outperforming fluconazole. Biocompatibility assays showed it is non-hemolytic (IC₅₀ > 1000 µg/mL), non-mutagenic, and highly selective for fungal cells (SI = 512.82), suggesting minimal human cell toxicity. In conclusion, the extract combines strong antifungal activity and favorable safety, with cost-effective preparation suitable for traditional medicine in resource-limited regions.

Background: Candida albicans is the most prevalent fungi isolated in endodontic infections. In this study, the ability of C. albicans biofilm to tolerate the novel solvent mixtures methyl ethyl ketone (MEK)/tetrachloroethylene (TCE) and MEK/orange oil (OOil) sequentially to the standard irrigation of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic (EDTA) was evaluated. Methods: Biofilm cell cultures of C. albicans SC 5314 were treated sequentially with NaOCl and EDTA and exposed to MEK/TCE or MEK/OOil. The effect of the antimicrobial treatment was evaluated using the disk diffusion method for planktonic culture, and the enumeration of colony-forming units (CFUs) and scanning electron microscope (SEM) for biofilm cell culture. Results: C. albicans mature biofilm (24 h) was significantly reduced in biomass and cell viability after solvent mixtures’ exposure, compared with the previous NaOCl and EDTA treatments. MEK/OOil combination caused a total reduction of biofilm, while with MEK/TCE, there was a 3-log (CFU/cm²) reduction compared with the sequence NaOCl and EDTA, and a 4-log (CFU/cm²) reduction compared with the control. Conclusions: The additional exposure of a preformed 24 h C. albicans biofilm to novel solvent mixtures MEK/TCE and MEK/OOil caused a positive antibiofilm impact, overcoming the performance of the conventional endodontic irrigating protocol.