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

ABSTRACT

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, 2,2ʹ-azinobis (3-ethylbenzothiazoline-6-sulfonic acid, β-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.

KEYWORDS:

• Rosemary (Rosmarinus officinalis L.)
• phenolics
• antioxidant activities
• bioclimatic area
• season

Acknowledgments

This work is dedicated in the memory of Ahmed YEDDES who passed away in November 2009 and I acknowledge all the staff in LPAM laboratory especially the chemical experts HAMMAMI Majdi and KHAMMASSI saber for their cooperation in hard time.

Disclosure statement

No potential conflict of interest was reported by the authors.