Supercritical Co2, Hydrodistillation Extractions of Salvia Officinalis L. Influence of Extraction Process on Antioxidant Properties

Salvia officinalis L. (Lamiaceae) is a perennial woody shrub, cultivated in the Mediterranean countries, mainly to obtain dried leaves used as raw material in medicine, perfumery and food industry. The aim of this paper is to compare the antioxidant properties and the chemical composition of essentials oils obtain by two extraction process: the hydrodistillation and the supercritical carbon dioxide extraction. The hydrodistillation is a traditional process used to obtain the essential oils from the sage while the supercritical fluid extraction (SFE) is a new technology tested on this plant. The chemical composition has been investigated by the performance of GC and GC/MS, and the antioxidant properties are compared using the DPPH free radical method. In the same time the effects of the extraction parameters on the yield were analysed. The composition of the organic phase obtained by hydrodistillation and SFE methods is widely different. The major constituents of oil obtained by hydrodistillation are: α/β-thujone, 1,8-cineol and camphor. Using the SFE process, the oil is mainly constituted by manool, leden and viridiflorol. Consequently the SFE method improves the antioxidant properties. INTRODUCTION The great demand of natural products such as essential oils supports the implantation of aromatic and medicinal plant cultures in Tunisia territory. Salvia officinalis L. called sage is a popular plant belongs to the family of Labiatae and native to the Mediterranean region. The sage essential oil has an industrial interest [1, 2] and especially the Dalmatian sage Salvia officinalis L. which is considered to possess the finest and the most characteristic aroma [3]. More recent studies on the biological activity of sage showed that the essential oil present some antimicrobial and antioxidant properties [4, 5]. It has tonic stimulant properties and it is used in perfumery, in cosmetics [5] and for liquors. The chemical composition of oil has been the subject of considerable studies [6-9]. Different studies showed that the chemical compositions depend on many parameters as the technique of extraction [10, 11], the geographical origin of the plant [12], and the part of the plant analysed [12, 13]. Although distillation is a very convenient method for extracting essential oils, some disadvantages are caused by the artefacts produced during the process, especially when thermolabile components are involved [14]. Supercritical fluid extraction (SFE) is an interesting technique to resolve the problem occurred by the hydrodistillation, and different study have been reported in the literature [15-19]. Concerning the antioxidants properties of sage [20-23] the different studies developed in the literature conclude that the top of the aerial part contribute mainly to the antioxidant activity. The aims of our study were: (i) to determine the chemical composition of essential oils of Salvia officinalis collected from Tunisia, extracted by hydrodistillation and supercritical fluid