Óleo essencial de Baccharis tridentata Vahl: composição química, atividade antioxidante e fungitóxica, e caracterização morfológica das estruturas secretoras por microscopia eletrônica de varredura

Abstract

This study aimed to evaluate the chemical composition and the antioxidant and fungitoxic activities of Baccharis tridentata essential oil, as well as to study the morphology of its secretory structures present on the leaf surface by scanning electron microscopy (SEM). The essential oil was extracted by hydrodistillation; the quantitative and qualitative analyses were performed on a gas chromatograph equipped with a flame ionization detector (FID) and coupled to a mass spectrometer, respectively. The antioxidant activity was determined by the methods of reduction of the DPPH stable radical and oxidation of the β-carotene/linoleic acid system. Fungitoxic activities were assessed by the in vitro bioanalytical test on the inhibition of the mycelial growth of the plant pathogens Fusarium oxysporum, Colletotrichum gloeosporioides and Rhizoctonia solani. The chemical composition revealed the presence of 28 compounds, with α-thujene (22.93%) as the major constituent. No antioxidant activity was observed in the tests used; however, there was fungitoxic activity against the mycelial growth of plant pathogens. Leaf surface studies by SEM revealed the presence of glandular trichomes on both abaxial and adaxial surfaces.