Supercritical Fluid Extraction of the Egyptian Rosemary (Rosmarinus officinalis) Leaves and Nigella sativa L. Seeds Volatile Oils and Their Antioxidant Activities

Abstract

Volatile oils of rosemary (Rosmarinus Officinalis) leaves and nigella sativa L seeds were isolated by supercritical fluid extraction (SFE) under suitable conditions of pressure and temperature. The isolated volatile oils were analysed by gas chromatography-mass spectrometry (GC-MS). The main components in rosemary oil are, 1,8–cineole (52.31 %), α- pinene (6.54 %), caryophyllene (z) (5.48 %) while the components, in nigella are,thymoquinone (41.05 %), β-cymene (10.64 %) and caryophyllene (1.89 %). The estimated compounds in both oils were grouped into four main classes, namely, monoterpene hydrocarbons, light oxygenated compounds, heavy oxygenated compounds and sesquiterpene hydrocarbons. The light oxygenated compounds in both oils recorded the highest values compared with the other classes, where 1,8–cineol and thymoquinone were the main components of this group in both rosemary and nigella volatile oils, respectively. Nigella volatile oil contains a considerable phenolic content (2.69 %); mostly carvacrol (1.41%) and thymohydro quinone (1.15 %). Both volatile oils revealed antioxidant and radical scavenging activities on 1,1-diphenyl-2-picryl-hydrazyl (DPPH) at various concentrations compared with the known synthetic antioxidants such as butyl hydroxyanisol (BHA). However, the observed remarkable antioxidant activities and free radical inhibitor effect of rosemary and nigella oils might be due to the considerable concentration of phenolic contents.