Effect of bioclimatic area and season on phenolics and antioxidant activities of rosemary (Rosmarinus officinalis L.) leaves

The aim of the present study was to determine the phenolic content and the antioxidant activity of rosemary collected from three different bioclimatic stages of Tunisia during four seasons. Ethanol and ethyl acetate extracts of rosemary leaves were isolated by Soxhlet and the contents of total polyphenols, total flavonoids and total condensed tannins of rosemary extracts were determined by spectrophotometric method. High performance liquid chromatography (HPLC) analysis allowed the quantification of the main phenolic compounds, namely rosmarinic acid and carnosic acid. Antioxidant assays were evaluated by 1,1-diphenyl-2-picrylhydrazyl radical-scavenging, 2,2MODIFIER LETTER PRIME-azinobis (3-ethylbenzothiazoline-6-sulfonic acid, beta-carotene bleaching, iron reducing power and ferric reducing antioxidant power assays. There was a strong correlation between antioxidant activity and phenolic content depending on bioclimatic and season effects.