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

BACKGROUND: Recurrence and resistance of Candida spp. infections is associated with the ability of these microorganisms to present several virulence patterns such as morphogenesis, adhesion, and biofilm formation. In the search for agents with antivirulence activity, essential oils could represent a strategy to act against biofilms and to potentiate antifungal drugs. OBJECTIVE: To evaluate the antivirulence effect of Origanum vulgare L. essential oil (O-EO) against Candida spp. and to potentiate the effect of fluconazole and nystatin. METHODS: The effect of O-EO was evaluated on ATCC reference strains of C. albicans and non-albicans Candida species. Minimum inhibitory concentration (MIC) was determined through broth microdilution assay. Adhesion to microplates was determined by crystal violet (CV) assay. An adapted scratch assay in 24-well was used to determine the effect of essential oil on biofilms proliferation. Viability of biofilms was evaluated by MTT reduction assay and through a checkerboard assay we determined if O-EO could act synergistically with fluconazole and nystatin. RESULTS: MIC for C. albicans ATCC-90029 and ATCC-10231 was 0.01 mg/L and 0.97 mg/L, respectively. For non-albicans Candida strains MIC values were 2.6 mg/L for C. dubliniensis ATCC-CD36 and 5.3 mg/L for C. krusei ATCC-6258. By using these concentrations, O-EO inhibited morphogenesis, adhesion, and proliferation at least by 50% for the strains assayed. In formed biofilms O-EO decreased viability in ATCC 90029 and ATCC 10231 strains (IC50 7.4 and 2.8 mg/L respectively). Finally, we show that O-EO interacted synergistically with fluconazole and nystatin. CONCLUSIONS: This study demonstrate that O-EO could be considered to improve the antifungal treatment against Candida spp.

Chemical Characterization of Lavandula dentata Essential Oil Cultivated in Chile and Its Antibiofilm Effect against Candida albicans.

Candida albicans is the most common human fungal pathogen, and with the increase in resistance rates worldwide, it is necessary to search for new pharmacological alternatives. Lavandula dentata L. essential oil is recognized as having antimicrobial properties. However, its effect against fungal biofilms has been poorly described. C. albicans-related infections involve the development of biofilms, which are highly resistant to conventional antifungals. In this work, we evaluated the antibiofilm effect of L. dentata L. essential oil against C. albicans. First, we characterized the essential oil by gas chromatography-mass spectrometry. The antifungal effect on C. albicans reference strains was evaluated by a disk diffusion assay and the minimal inhibitory concentration was obtained through a microdilution assay. The effect of the essential oil on the adhesion ability of C. albicans was determined through a crystal violet assay, and morphogenesis inhibition was assessed by light microscopy. The effect of the essential oil on the microarchitecture of biofilms was evaluated through scanning electron microscopy. Finally, the antibiofilm effect was evaluated through an adapted biofilm scratch assay and XTT viability assay. The main constituent of the essential oil was the monoterpenoid eucalyptol (60%). The essential oil presented minimal inhibitory concentrations of 156 and 130 µg/mL against two strains assayed. This minimal inhibitory concentration inhibited adhesion, morphogenesis, biofilm formation, altered microarchitecture, and decreased the viability of established biofilms formed on abiotic surfaces for both strains assayed. This study demonstrates that the essential oil from L. dentata could be a promising treatment against C. albicans biofilms.

Antioxidant properties of a dry product from Vitis vinifera seeds (Leucoselect) in rat liver endoplasmic reticulum / Propiedades antioxidantes de un producto seco de semillas de Vitis vinifera (Leucoselect) en retículo endoplásmico de hígado de rata

Leucoselect is a commercial dry product obtained from grape seeds and enriched in procyanidins, which display antioxidant activity in virtue to their ability to scavenge oxygen free radicals and to chelate transition metal ions. The hypoxanthine/xanthine oxidase and Cu2+/ascorbate systems are capable of generating reactive oxygen species; the latter system can also promote non-specific binding of copper ions to proteins. Therefore, we assessed the ability of Leucoselect to inhibit oxidative phenomena elicited by both oxidative systems on rat liver microsomes: lipid peroxidation, oxidation of protein thiols, and inhibition of the cytochrome P450 system. The antioxidant activity of Leucoselect was a reflection of its ability to scavenge oxygen free radicals, chelate copper ions, and protect microsomal membranes through direct interaction. These mechanisms were displayed in a dependent manner with the type of biomolecule studied and also with the oxidative system employed, which is an interesting phenomenon to consider when evaluating the antioxidant activity of herbal products.

Leucoselect es un producto comercial seco obtenido de semillas de uva y enriquecido en procianidinas, las cuales presentan actividad antioxidante debido a su capacidad para atrapar radicales libres y quelar metales de transición. Los sistemas hipoxantina/xantina oxidasa y Cu2+/ascorbato generan especies reactivas del oxígeno; este último sistema también promueve la unión inespecífica de iones cobre a proteínas. Por lo tanto, evaluamos la capacidad de Leucoselect para inhibir los fenómenos oxidativos producidos por ambos sistemas oxidantes en microsomas hepáticos de rata: lipoperoxidación, oxidación de tioles proteicos e inhibición de la actividad del sistema citocromo P450. La actividad antioxidante de Leucoselect fue un reflejo de su capacidad de atrapar radicales libres del oxígeno, quelar iones cobre y proteger membranas microsómicas por interacción directa. Dichos mecanismos se manifestaron en forma dependiente del tipo de biomolécula estudiada y del sistema oxidante empleado, fenómeno interesante de considerar al evaluar la actividad antioxidante de preparados herbales.