Avaliação da atividade e modo de ação antifúngica do óleo essencial da entrecasca do caule de Gallesia integrifolia (Spreng.) Harms, em modelos experimentais in vitro

Abstract

: Infections have always played a prominent role in human health issues. Even with such scientific and technological evolution in medicine, the fight against the most diverse microorganisms is still challenging. Gallesia integrifolia (Spreng.) Harms, belonging to the Phytolaccaceae family, is a native and endemic tree species in Brazil, with distribution in all Brazilian regions. Known mainly as pau-d'alho, its stem bark decoction is used in the treatment of infections, inflammation, gastric ulcers, and other diseases by different Brazilian ethnic groups. The essential oil extracted from the inner stem bark of Gallesia integrifolia (OEGi) was shown to be active against bacteria and gastric ulcers, in in vitro and in vivo tests. Objective: To evaluate the activity and mode of antifungal action of OEGi in experimental models in vitro. Method: OEGI was obtained by steam distillation using a Clevenger type apparatus. For the evaluation of the antifungal activity of OEGi, the method of disk diffusion and microdilution in broth was used in vitro. To characterize the type of OEGI action, the minimum fungistatic and/or fungicidal concentration (CFM) was determined. To determine the mode of action of OEGi, sorbitol and ergosterol tests were performed on Saccharomyces cerevisiae, in vitro. In addition, the effect of OEGi on the adhesion to the surface of human oral epithelial cells and the formation of Candida albicans germ tube in vitro was evaluated. Results: OEGi presented a wide and varied spectrum of fungicidal action against different fungi: yeasts, yeast forms and filaments. Its antifungal mechanism of action seems to depend at least in part on the inhibition of cell wall synthesis or assembly, as well as on the reduction of fungal pathogenicity, by inhibiting both virulence factors. This effect may be due to the combined action of polyphenols, flavonoids and organosulfur class compounds. Conclusion: The fungicidal properties of OEGi against various fungi, reinforce its popular use for infections caused by these microorganisms. OEGi showed fungicidal action of a wide and varied spectrum, possibly because it inhibits cell wall formation, as well as virulence factors. These factors added to its low toxicity make OEGi a good candidate for the development of a new antifungal herbal medicine.