Seasonal variation of essential oil in rosmarinus officinalis leaves in sardinia

Rosmarinus officinalis L. is an aromatic plant belonging to the Lamiaceae family widely distributed in the Mediterranean area. The interest on this species is related to the multiple uses of the plant as a food ingredient, in the pharmaceutical and cosmetic industries. The chemical composition of essential oil (EO) from 5 accessions of R. officinalis L., collected monthly through a full year in Sardinia, has been studied by gas chromatography (GC) and GC-mass spectrometry technique. The EO ranged from 0.29% to 0.89%. The qualitative determinations revealed the presence of 27 compounds belonging to 6 chemical groups (hydrocarbon monoterpene, alcohols, aldehydes, ketones, esters, hydrocarbon sesquiterpene). Overall the GC-flame ionization detector analysis showed the presence of 7 major compounds: α-pinene (26%-28%), camphene (5%-8%), 1,8-cineole (15%-25%), borneol (5%- 11%), camphor (3%-12%), verbenone (6%-15%), and bornyl acetate (4%-7%). Chromatographic data were also subjected to a chemometric approach that evidenced discrimination of the samples according to the site of collection.