Effect of Phenological Stages on Essential Oil Content, Composition and Rosmarinic Acid in Rosmarinus Officinalis L.

Rosemary (rosmarinus officinalis l.) is an important medicinal plant that contained a wide range of secondary metabolites such as rosmarinic acid. in this study, essential oil content and composition and rosmarinc acid were determined at three phenological stages (before flowering, full flowering and fruit set stages). hydro distillation method was used for essential oil extraction and gc and gc/ms was used for essential oil composition. on the basis of the obtained results rosemary plants in full flowering stage had higher amount of essential oil (1.99 ml/100 g dry weight) than in before flowering and fruit set stages (1.2 and 1.01 ml/100 per g dry weight, respectively). the extracted essential oil was contained 1,8-cineole, α-pinene, verbenone, camphor, geraniol, borneol acetae, camphene and linalool as major constituents. these constituents were affected by phenological stages. before flowering, 1,8-cineole, α-pinene and verbenone (13.68%), in full flowering, 1,8-cineole (17.90%) and in fruit set α-pinene (21.77%) were the main constituents of the reosemary essential oil. using hplc analysis on leaf extract showed that the highest amount of rosmarinic acid (25.92mg/g dw) was observed in the fruit set stage. in conclusion, for essential oil content full flowering stage can be recommended for harvesting of rosmarinus officinalis l. and for rosmarinic acid, fruit set stage can be the best time for harvesting of this medicinal plant.