title: In Vitro Activity of Melaleuca alternifolia (Tea Tree) in Its Free Oil and Nanoemulsion Formulations Against Pythium insidiosum.
abstract: Pythium insidiosum is an important aquatic oomycete which can cause pythiosis in both animals and humans. This microorganism shows low susceptibility to antifungal drugs available. This study analyzed the in vitro antimicrobial activity of Melaleuca alternifolia in its free oil (FO) and nanoemulsion (NE) formulations against Brazilian P. insidiosum isolates. The antimicrobial activity evaluation was performed by the broth microdilution method according to CSLI M38-A2 document adapted to phytopharmaceuticals. Twenty-six P. insidiosum isolates were evaluated, and the minimum inhibitory concentration was determined at 100 % growth inhibition. Melaleuca alternifolia essential oil or FO was obtained commercially. The NE containing 1 % M. alternifolia essential oil was prepared by the spontaneous emulsification method. All P. insidiosum isolates evaluated showed minimum inhibitory concentrations (MIC) ranging from 531.5 to 2125 μg/mL for the FO formulation; MIC50and MIC90showed values between 1062.5 and 2125 μg/mL, respectively. When the NE formulation was evaluated, MIC values ranged from 132.7 to 2125 μg/mL and both MIC50and MIC90corresponded to 1062.5 μg/mL. FO and NE formulations of M. alternifolia showed antimicrobial activity against P. insidiosum. This study demonstrated that M. alternifolia oil can be an additional therapy in pythiosis treatment; however, further studies are needed to evaluate the applicability of the plant essential oils in the treatment of clinical pythiosis.
authors.affiliation: Laboratório de Micologia, Departamento de Microbiologia e Parasitologia, Prédio 18, Sala 14, Universidade Federal de Pelotas, Campus Capão do Leão, s/n°, Pelotas, RS, 96010-900, Brazil.
authors.forename: Júlia
authors.initials: J
authors.lastname: de Souza Silveira Valente
authors.affiliation: Laboratório de Micologia, Departamento de Microbiologia e Parasitologia, Prédio 18, Sala 14, Universidade Federal de Pelotas, Campus Capão do Leão, s/n°, Pelotas, RS, 96010-900, Brazil.
authors.forename: Anelise
authors.initials: A
authors.lastname: de Oliveira da Silva Fonseca
authors.affiliation: Laboratório de Micologia, Departamento de Microbiologia e Parasitologia, Prédio 18, Sala 14, Universidade Federal de Pelotas, Campus Capão do Leão, s/n°, Pelotas, RS, 96010-900, Brazil.
authors.forename: Carolina Litchina
authors.initials: CL
authors.lastname: Brasil
authors.affiliation: Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av. Roraima 1000, Prédio 44, Campus Universitário Camobi, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Lauren
authors.initials: L
authors.lastname: Sagave
authors.affiliation: Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Av. Roraima 1000, Prédio 20, Campus Universitário Camobi, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Fernanda Cramer
authors.initials: FC
authors.lastname: Flores
authors.affiliation: Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Av. Roraima 1000, Prédio 20, Campus Universitário Camobi, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Cristiane
authors.initials: C
authors.lastname: de Bona da Silva
authors.affiliation: Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av. Roraima 1000, Prédio 44, Campus Universitário Camobi, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Luís Antônio
authors.initials: LA
authors.lastname: Sangioni
authors.affiliation: Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av. Roraima 1000, Prédio 44, Campus Universitário Camobi, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Luciana
authors.initials: L
authors.lastname: Pötter
authors.affiliation: Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Av. Roraima 1000, Prédio 20, Campus Universitário Camobi, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Janio Morais
authors.initials: JM
authors.lastname: Santurio
authors.affiliation: Centro de Ciências Rurais, Universidade Federal de Santa Maria, Av. Roraima 1000, Prédio 44, Campus Universitário Camobi, Santa Maria, RS, 97105-900, Brazil.
authors.forename: Sônia
authors.initials: S
authors.lastname: de Avila Botton
authors.affiliation: Laboratório de Micologia, Departamento de Microbiologia e Parasitologia, Prédio 18, Sala 14, Universidade Federal de Pelotas, Campus Capão do Leão, s/n°, Pelotas, RS, 96010-900, Brazil. danielabrayer@gmail.com.
authors.forename: Daniela Isabel Brayer
authors.identifier: http://orcid.org/0000-0003-4374-677X
authors.initials: DI
authors.lastname: Pereira
mesh_terms: D000935:Antifungal Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001938:Brazil; D004655:Emulsions / Q000494:pharmacology*; D031650:Melaleuca / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D009822:Oils, Volatile / Q000302:isolation & purification / Q000494:pharmacology*; D011775:Pythium / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000935:Antifungal Agents; D004655:Emulsions; D009822:Oils, Volatile
keywords: Medicinal plants; Nanostructured systems; Oomycete; Pythiosis