ABSTRACT
The antioxidant properties of medicinal plants as natural resources are located attention by researchers for use in food and biological systems. The purpose of this study was to evaluate antioxidant activity of essential oil and extracts of Mentha longifolia as a substitute for synthetic antioxidants. In this laboratory study, the essential oil plant was analyzed by GC / MS. Antioxidant activity of essential oil and extracts was evaluated with DPPH free radical scavenging and beta-carotene bleaching methods and was compared with synthetic antioxidant BHT. The major components of Mentha longifolia essential oil were monoterpen oxygen compounds including Cis-piperitone epoxide%28.23, Alpha-terpineol%18.64, Menthone%10.97, Pulegone%9.73 and Cis-piperitone epoxide%8.73. IC50 of Mentha longifolia essential oil was 1765 +/- 5 microg / ml and IC50 of aqueous, ethanolic and methanolic extracts were 100 +/- 1.2, 53.8 +/- 0.58, 50 +/- 0.5, while IC50 of BHT was 4.9 +/- 0.25 microg / ml.furthermore, in beta-carotene bleaching method, the antioxidant activity essential oil was 60 percent and IC50 of aqueous, ethanolic and methanolic extracts were estimated73.27,89.88, 84.79 percent respectively. while parameters for BHT 95 +/- 0/9 percent. The antioxidant properties of essential oil tested was not significant, while the extracts showed considerable antioxidant properties that candidate them for using in foods as a natural antioxidant