Constituintes voláteis, fenóis totais, capacidade antioxidante e biológica de folhas, flores e raizes da Vernonia brasiliana Less

Abstract

The species Vernonia brasiliana Less., a.k.a. assa-peixe, assa-peixe preto, assa-peixe roxo, pau de múquem, pau de muqueca and manjericão de cavalo, is a very used plant in folk medicine. The root syrup fights against cough and flu; the bud tea is used in eye diseases and respiratory failure; the leaves are used to inhibit inflammatory rheumatism, hepatic colic and some cases of hemorrhage. The objectives of the present work were to produce ethanolic extracts and essential oil of the plant parts (leaves, flower and root) of Vernonia brasiliana. Also, we evaluated the level of phenolic compounds, proanthocyanidins, antioxidant and antimicrobial activity, oxidation potentials level, and identified the compounds of the essential oils. The oils were tested against Staphylococcus aureus and Escherichia coli in vitro bacteria and against Trypanosoma cruzi and Leishmania, in vitro protozoa. The ethanolic extracts presented a total phenol by Folin-Ciocalteau method of 133, 127 and 87 mg of GAE (gallic acid equivalents) per gram of sample, respectively for leaves, flowers and root. The condensed tannins presented values of 122, 147 and 109 mg of catechin equivalents (CE) per gram of sample, respectively for flower, leaves and root. The antioxidant activity by DPPH method presented CE50 values 25, 27 and 37 for leaves, root and flowers, respectively. The diferential pulse voltammetry presented values of 0.205, 0.232 and 0.199 volts for oxidation potential and 158.2, 160.3 and 113.2 microcouloumbs of charge for leaves, flowers and root, respectively. The compounds with higher percentage identified in the essential oil were: modheph-2- ene, alpha-isocomene, ciperene, beta-isocomene and beta-caryophyllene in the root; palmitic acid, hexan-1-ol and septacosane in the flower; and trans-caryophyllene, germacrene D, bicyclogermacrene, spathulenol and palmitic acid in the leaves. There was no evidence of antimicrobial effect for extracts and essential oil against Staphylococcus aureus and Escherichia coli. The extracts of Vernonia brasiliana were not significant because they are considered toxic at concentrations that were active aganst antitrypanossoma and antileishmaina. However the three oils showed a valid activity against Trypanosoma cruzi and Leishmania amazonensis, since it shows no toxicity at concentrations that have shown activity.