Estudo da composição dos monoterpenos das plantas Juníperus virginiana, Juníperus bermudiana e Thuja orientalis

Abstract

The present work was carried out on the essential oil obtained by hydrodistillation of the leaves of Juníperus virginiana (Cedro), Juníperus bermudiana (Cedro das bermuda) and Thuja orientalis (Tuia) plants. Given the complexity of the investigated samples, this study reports the chemical and enantiomeric composition of monoterpenes, as the first stage of an investigation program on this family. This study is part of the ongoing research project at the Department of Chemistry of the Faculty of Sciences, which aims to research natural products, their valorization and possibility of application as a source of fragrances, pheromones, etc. and the consequent enrichment of knowledge about the Mozambican flora. The essential oils obtained from dry leaves, whose yields were 0.28%, 0.31% and 0.49%, respectively from Juníperus virginiana, Juníperus bermudiana and Thuja orientalis, were analyzed by Gas Chromatography, using a polar capillary column (DB-Wax) . The identification of the compounds was made based on the comparison of the retention times of the standards. The results obtained reveal the presence of the compounds: a-pinene, β-pinene, camphene, 3-carene, a-phelandrene, myrcene, limonene, y-terpinene and p-cimene as the main constituents. The hydrocarbon composition of the two Juniperus species was compared to each other and to the composition of Thuja orientalis, and it was found that there are similarities between them. However, they can be distinguished by their content of a-pinene (majority in Thuja orientalis) and limonene (majority in Juniperus species). The enantiomeric ratio was determined by two-dimensional gas chromatography using a chiral column (β-cyclodextrin), and it was found that (-) limonene is present with a high degree of optical purity (99%) in juniperus viriginiana, and in Thuja orientalis the most optically pure component is a-(+)-pinene (90%). (TRADUÇÃO NOSSA)