Anatomia foliar e caulinar, caracterização química e atividades biológicas do óleo essencial de Ocotea porosa (NEES & MART.) Barroso: uma abordagem interdisciplinar

Abstract

Ocotea is one of the most important genera of the family Lauraceae and comprises about 350 species, being found, especially in Latin America. In Brazil, species of the genus are economically important for using the wood. However, the characterization of the species by morphological, chemical and biological activities involving the essential oil are precarious. The objective of this work was to study the morpho-anatomy of the leaves of Ocotea porosa in order to help in the identification of this taxon, determine the chemical composition, investigate the cytotoxic potential of the essential oil and the antioxidant activity. The botanical material was collected in União da Vitória (Paraná, Brazil). From the usual methods of optical microscopy and scanning electron microscopy, it has been proven that the leaves are hypostomatic, have paracytic stomata and have non-glandular trichomes. The central vein and the petiole are biconvex and have a collateral vascular bundle in an open arch. The stem has a sclerenchymatic layer and calcium oxalate crystals. Phenolic compounds are found in the epidermis, phloem and xylem of the central vein, petiole and stem. The main anatomical marker of the stem is the presence of a continuous sclerenchymatous sheath in the pith. Two shapes of calcium oxalate crystals namely crystal sand and raphides are observed in this species. By means of hydrodistillation of leaves, a content of 1.03% ± 0.7% of essential oil was obtained. The essential oil of O. porosa were identified by GC-MS and the major compounds were bicyclogermacrene (24.62%), α-pinene (19.71%) and β-pinene (13.86%). As for cytotoxicity assessed by the MTT method, the essential oil of O. porosa was shown to be cytotoxic to the cell lines murine fibroblast (McCoy, ATCC® CRL-1696), murine melanoma (B16F10) and human breast adenocarcinoma (MCF7). Thus, there was no selectivity against the tumor cells under study. As for the antioxidant analysis, the essential oil did not show activity.