Atividade in vitro dos óleos essenciais de Melaleuca alternifolia, Mentha piperita e Origanum vulgare isolados, combinados entre si e com antifúngicos, frente ao oomiceto Pythium insidiosum

Abstract

Pythium insidiosum causes pythiosis, a severe and emerging disease that affects mammals. The limitations involving the conventional antifungal therapies is in part justified by the absence of ergosterol in the plasma membrane of this oomycete. Despite the advancement of research, treatment of pythiosis is not fully established. In this study, in vitro antimicrobial activity of Melaleuca alternifolia in free oil and nanoemulsion was tested against the oomycete P. insidiosum (n=26). Additionally, the profile of in vitro susceptibility of Brazilian isolates of P. insidiosum (n = 20) was verified to the essential oils of Melaleuca alternifolia, Mentha piperita and Origanum vulgare, isolated, in their combinations and combinations with itraconazole and terbinafine. Susceptibility tests were achieved following the M38-A2 document and all combinations were performed by cherkerboard microdilution test. All evaluated essential oils presented antimicrobial activity against P. insidiosum. However, the best results were demonstrated using O. vulgare. It was observed synergistic effect and/or indifferent to all combinations of essential oils tested, emphasizing that the combination of M. piperita and O. vulgare resulted in 65% of synergism. In combinations of essential oils with itraconazole or terbinafine were observed marked synergistic effect for all combinations with itraconazole, especially the combination with M. alternifolia, which resulted in 95% synergistic effect. Combinations with terbinafine and essential oils showed indifference or antagonistic effect. This is the first study evaluating in vitro combination of essential oils of M. alternifolia, M. piperita and O. vulgare against Brazilian isolates of P. insidiosum. The results obtained suggest that the combination of bioactive compounds from plants among themselves and / or with antifungal drugs may provide an alternative therapy in the control of P. insidiosum infection. However, further studies are essential to determine new therapeutic protocols involving these proposed combinations.