Origanum vulgare L. essential oil inhibits virulence patterns of Candida spp. and potentiates the effects of fluconazole and nystatin in vitro

Essential oils as promising treatments for treating Candida albicans infections: research progress, mechanisms, and clinical applications

Candida albicans: (C. albicans) is a prevalent opportunistic pathogen that can cause severe mucosal and systemic fungal infections, leading to high morbidity and mortality rates. Traditional chemical drug treatments for C. albicans infection have limitations, including the potential for the development of drug resistance. Essential oils, which are secondary metabolites extracted from plants, have gained significant attention due to their antibacterial activity and intestinal regulatory effects. It makes them an ideal focus for eco-friendly antifungal research. This review was aimed to comprehensively evaluate the research progress, mechanisms, and clinical application prospects of essential oils in treating C. albicans infections through their antibacterial and intestinal regulatory effects. We delve into how essential oils exert antibacterial effects against C. albicans infections through these effects and provide a comprehensive analysis of related experimental studies and clinical trials. Additionally, we offer insights into the future application prospects of essential oils in antifungal therapy, aiming to provide new ideas and methods for the development of safer and more effective antifungal drugs. Through a systematic literature review and data analysis, we hope to provide insights supporting the application of essential oils in antifungal therapy while also contributing to the research and development of natural medicines. In the face of increasingly severe fungal infections, essential oils might emerge as a potent method in our arsenal, aiding in the effective protection of human and animal health.

Gallic acid triphenylphosphonium derivatives TPP+-C10 and TPP+-C12 inhibit mitochondrial function in Candida albicans exerting antifungal and antibiofilm effects

AIMS

To evaluate the antifungal and antibiofilm activity of gallic acid derivatives TPP+-C10 and TPP+-C12 and their effects on mitochondrial function on two Candida albicans reference strains (ATCC 90029 and ATCC 10231).

METHODS AND RESULTS

First, we determined minimal inhibitory concentration (MIC) using a microdilution assay. Both compounds exerted antifungal effects, and their MICs ranged from 3.9 to 13 µM, with no statistically significant differences between them (P > 0.05, t-test). These concentrations served as references for following assays. Subsequently, we measured oxygen consumption with a Clark electrode. Our observations revealed that both drugs inhibited oxygen consumption in both strains with TPP+-C12 exerting a more pronounced inhibitory effect. We then employed flow cytometry with TMRE as a probe to assess mitochondrial membrane potential. For each strain assayed, the compounds induced a decay in transmembrane potential by 75%-90% compared to the control condition (P < 0.05, ANOVA). Then, we measured ATP levels using a commercial kit. TPP+-C12 showed a 50% decrease of ATP content (P < 0.05 ANOVA), while TPP+-C10 exhibited a less pronounced effect. Finally, we assessed the antibiofilm effect using the MTT reduction assay. Both compounds were effective, but TPP+-C12 displayed a greater potency, requiring a lower concentration to inhibit 50% of biofilms viability (P < 0.05, t-test).

CONCLUSIONS

Derivatives of gallic acid linked to a TPP+ group exert antifungal and antibiofilm activity through impairment of mitochondrial function in C. albicans.

Synergy and Mechanism of Leflunomide Plus Fluconazole Against Resistant Candida albicans: An in vitro Study

Objective

The global rise in the resistance of Candida albicans to conventional antifungals makes Candida albicans infections harder to treat. The main objective of this study was to investigate the antifungal effects and underlying mechanisms of leflunomide in combination with triazoles against resistant Candida albicans.

Methods

In this study, the microdilution method was used to determine the antifungal effects of leflunomide in combination with three triazoles on planktonic cells in vitro. The morphological transition from yeast to hyphae was observed under a microscope. The effects on ROS, metacaspase, efflux pumps, and intracellular calcium concentration were investigated, respectively.

Results

Our findings suggested that leflunomide + triazoles showed a synergistic effect against resistant Candida albicans in vitro. Further study concluded that the synergistic mechanisms were resulted from multiple factors, including the inhibited efflux of triazoles, the inhibition of yeast-to-hyphae transition, ROS increasing, metacaspase activation, and [Ca²⁺]_i disturbance.

Discussion

Leflunomide appears to be a potential enhancer of current antifungal agents for treating candidiasis caused by resistant Candida albicans. This study can also serve as an example to inspire the exploration of new approaches to treating resistant Candida albicans.

Potential Applications of Essential Oils for Environmental Sanitization and Antimicrobial Treatment of Intensive Livestock Infections

The extensive use of antibiotics has contributed to the current antibiotic resistance crisis. Livestock infections of Salmonella spp, Clostridium spp. and E. coli antimicrobial-resistant bacteria represent a public threat to human and animal health. To reduce the incidence of these zoonoses, essential oils (EOs) could be effective antibiotic alternatives. This study aims at identifying EOs safe for use, effective both in complementary therapy and in the environmental sanitization of intensive farming. Natural products were chemo-characterized by gas chromatography. Three S. Typhimurium, three C. perfringens and four E. coli strains isolated from poultry and swine farms were used to assess the antimicrobial properties of nine EOs and a modified GR-OLI (mGR-OLI). The toxicity of the most effective ones (Cinnamomum zeylanicum, Cz; Origanum vulgare, Ov) was also evaluated on porcine spermatozoa and Galleria mellonella larvae. Cz, Ov and mGR-OLI showed the strongest antimicrobial activity; their volatile components were also able to significantly inhibit the growth of tested strains. In vitro, Ov toxicity was slightly lower than Cz, while it showed no toxicity on G. mellonella larvae. In conclusion, the study confirms the importance of evaluating natural products to consolidate the idea of safe EO applications in reducing and preventing intensive livestock infections.