Estudo fitoquímico e avaliação antioxidante de Lippia sidoides

Abstract

This work describes the phytochemical reinvestigation of the specie Lippia sidoides, belonging to the family Verbenaceae, aiming at the isolation and structural elucidation of secondary metabolites new or known. Chemical studies conducted with the ethanolic extract of the roots and leaves of the species allowed the isolation of tree and characterization of seven constituents. Of the ethanolic extract of the roots was isolated the naphthoquinone tecomaquinone I, and the ethanolic extract of the leaves was isolated the monoterpene 5- hydroxymethyl-2-isopropylphenol, the flavanone naringenin, the mixture of flavonoids eriodictyol and hispidulin, and the mixture of dihydrochalcones 3- hydroxyphloridzin and phloridzin. The mixture of dihydrochalcones was subjected to reaction acetylation with acetic anhydride/pyridine, resulting in the acetylation of all hydroxyl. Structure determination of the substances was performed by spectrometric techniques such as infrared (IR), mass spectrometry (MS) and nuclear magnetic resonance of hydrogen (1H NMR) and carbon-13 (13C NMR) including two-dimensional techniques (COSY, HSQC and HMBC) and comparison with data reported in the literature. The antioxidant activity of the substances isolated and of the ethanolic extract of the leaves was evaluated by method the inhibition of free radicals (DPPH), observing a significant activity, especially of the ethanolic extract of the leaves, of the mixture of flavonoids and the mixture of dihydrochalcones.