Óleos Essenciais na Amazônia: Estudo Sazonal de Ocimum minimum Cultivado no Estado do Pará

Abstract

Species of the genus Ocimum L. (Lamíaceae), distributed in tropical and subtropical climates of the old and new world, provide essential oils used in the cosmetics and perfumery industry. The species Ocimum minimum L., known as basil, alfavaca, and alfavaca, is a plant native to India, known worldwide for its pleasant aroma and medicinal properties, such as antispasmodic, antifebrile, sudorific, diuretic, antirheumatic, digestive, tonic, and antidiabetic. In the state of Pará this species is economically important, being cultivated by small farmers for sale in the open markets of Belém, and for the extraction of essential oil. This study was conducted to evaluate the occurrence of variation in oil yield and chemical constituents in the two Amazonian climatic periods (summer and winter). Samples were collected in Ananindeua, separated into flowers, leaves and stem, and dried for 7 days. The essential oils were obtained by hydrodestillation in a Clevenger type glass system for 3 hours. The chemical composition analysis was done using gas chromatography and gas chromatography coupled to mass spectrometry. The main constituents of the oils from O. minimum collected in August (Amazonian summer) 2003 were metUchavicol (leaf: 38.6%, stem: 35.0%, flower: 19.0%), 1,8-cineole (leaf: 16.3%; stem: 14.3%, flower: 13.6%) and limonene (leaf: 13.7%, stem: 13.2%, flower: 13.8%). In March 2004 (Amazonian winter), the data obtained were: metllchavichol (leaf: 33.8%, stem: 26.2%, flower: 2.9%), 1,8-cineole (leaf: 17.7%, stem: 8.6%, flower: 14.0%) and limonene (leaf: 15.4%, stem: 10.8%, flower: 15.6%). The relative proportion of the quinucic constituents were different in the organs analyzed, however, no significant variations were observed in relation to the collection period. The oil yield of leaves and flowers was higher in winter (4.3% and 7.1%, respectively). The data obtained indicate that the climatic period does not cause a significant modification in the chemical composition of the oil, however, the collection in the winter period will provide a higher yield of essential oil.