Estudo fitoquímico de Mitracarpus frigidus (Willd. ex Reem Schult.) K. Schum. biomonitorado pela atividade antimicrobiana e a avaliação das atividades citotóxica, antioxidante e leishmanicida

Abstract

The methanolic extract of the aerial parts of Mitracarpus frigidus (Willd. ex Reem Schult.) K. Schum. (Rubiaceae) and their partitions were evaluated for antimicrobial activity against eleven strains of bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica sorovar tythimurium, Shigella sonnei, Klebsiella pneumoniae, Escherichia coli, Micrococcus luteus, Enterococcus faecalis, Enterobacter cloacae, Streptococcus pyogenes e Bacillus cereus) and two yeasts (Candida albicans e Cryptococcus neoformans). Antileishmanial activity was tested for promastigotes forms of Leishmania (L. chagasi e L. amazonensis) and cytotoxicity was analysed by brine shrimp (Artemia salina) lethality assay. Antioxidant activity (assay with DPPH and reduction power), phytochemical screening and the contents of phenolics and flavonoids were also investigated. The most significative cytotoxic activity were found for hexane partition (LC50 = 61 µg/ml); the EtOAc and n-BuOH partitions presented excellent antioxidant activity (IC50 = 7 and 9 µg/ml, respectively, by the DPPH assay and EC50 = 35 and 40 µg/ml, respectively, by reduction power assay) which was positively correlated with the contents of phenolics and flavonoids. Hydromethanolic partition showed expressive activity against the promastigotes forms of L. amazonensis (IC50 = 9 µg/ml). CH2Cl2 partition present an intense antimicrobial activity, mainly against C. neoformans e B. cereus with MIC = 0,010 e 0,020 µg/ml, respectively and also antileishmanial with IC50 = 7 µg/ml for L. chagasi. The CH2Cl2 partition was fractionated and gave several fractions with cytotoxic, antimicrobial and antileishmanial activity. Bioauthography showed that triterpenes and alkaloids were responsible for antifungal activity of the fractions. The extracted alkaloids presented antimicrobial activity against B. cereus, P. aeruginosa and C. neoformans with MIC = 0,039 mg/ml. The essential oil presented linalol and eugenol acetate as the major components and an excellent antifungal activity with MIC of 0,063 mg/ml for C. albicans and of 0,008 mg/ml for C. neoformans. This study is the first report of the chemical-biological characterization of M. frigidus.