Abstract
The evaluation of the essential oil (EO) profile of several cultivars of Rosmarinus officinalis, usually not used for food, and the assessment of their antioxidant activity as potential sources of natural antioxidants were studied in this work. Five different cultivars of Rosmarinus officinalis: R. officinalis ‘Alba'; R. officinalis ‘Blue Rain'; R. officinalis ‘Corsican Blue'; R. officinalis ‘Israeli'; R. officinalis ‘Majorca Pink’ and one hybrid of rosemary, Rosmarinus x lavandulaceus Noë, cultivated at CREA Sanremo (Italy), were hydrodistilled separately and the obtained EOs were analysed by GC-MS. Monoterpenes predominated in all the EO profiles but oxygenated monoterpenes were the most abundant constituents in R. officinalis ‘Blue Rain’, R. officinalis ‘Corsican Blue’, R. officinalis ‘Israeli’ and R. officinalis ‘Majorca Pink’. R. x lavandulaceus Noë and R. officinalis ‘Alba’ showed percentages of monoterpene hydrocarbons and oxygenated monoterpenes very similar. α-pinene, camphene, 1,8-cineole, camphor, borneol, verbenone, isobornyl acetate and β-caryophyllene were the main constituents present in all the plant cultivars, even though in different percentages. Myrcene predominate in R. officinalis ‘Alba’ (30.3 %), 1,8 cineol in R. officinalis ‘Blue Rain’ and R. officinalis ‘Israeli’ (21.9% and 26.4%, respectively), while camphor was the main constituent in R. officinalis ‘Majorca Pink’ (42.5%) and in R. x lavandulaceus (24.2%). R. officinalis ‘Corsican Blue’ showed similar amount of the three main components, verbenone, camphor and isobornyl acetate (18.5% >18.2% >15.4%, respectively). All the EOs were also tested for their antioxidant activity using the ferric reducing antioxidant power (FRAP) method and the stable radical DPPH. R. x lavandulaceus Noë showed the highest antioxidant activity, two folds more than that observed in R. officinalis ‘Israeli’.