Extração do óleo essencial de Ocimum gratissimum varo macrophyllum L. por hidrodestilação, destilação-extração simultânea e solvente: seleção do melhor método de extração

Abstract

and medicinal, sold in street markets and supermarkets, mainly for medicinal use, and in aromatic baths. The species occurs in two botanical varieties (var. macrophyllum and varogratissimum), distinct also in terms of genetics and chemistry of its essential oils. In Pará, the macrophyllum variety is cultivated for commercialization. Considering that the essential oil tor varies in the plant tissues, and can vary with the extraction method used, besides the importance of rapid methods of essential oil extraction in potentially useful species, we analyzed the yield and chemical composition of the volatile components from the leaves of O. gratissimum varo macrophyllum leaves through hydrodistillation (HD), simultaneous distillation-extraction (DES) and the solvent hexane (SH), also analyzing by Scanning Electron Microscopy (SEM), the impact caused in the secretory structures of the leaves after the extractions. The products obtained were analyzed by gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC/MS), using capillary column DB5-MS, temperature program: 60°C-240°C (3°C/min), detector and injector temperature 250°C. Three samples of adult leaves were used for SEM analysis after fixation in 70% alcohol. The yields obtained for oils and extracts were: HD = 1.12 %, DES = 0.08 %, and SH = 8.00%. The chemical composition of O. gratissimum varo macrophyllum leaves varied significantly when extracted by HD and DES: thymol (HD = 25.4%; DES = 52.2%), y-terpinene (HD = 38.2%; DES = 23.6%), but were similar to those cited in the literature for samples of this variety grown in Pará. The chemical profile of the hexanic extract was very different, with an almost total absence of the monoterpenes, and the presence of two more polar compounds. In the SEM analysis it was observed that the number of collapsed structures was higher after hydrodistillation. The data obtained were indicative that hydrodistillation is an excellent method for extraction of "alfavacao" oil, resulting in a good oil yield and a good chemical composition, and is also simpler than the others used.