Effect of extraction method on antioxidant activity and some secondary metabolites of Mentha aquatic L. extract

With the improvement in living conditions, consumers increasingly reject food prepared with additives of chemical origin due to health issues. There is an present increasing interest both in the industry and in scientific community for aromatic herbs because of their strong antioxidant, which exceed many currently used natural and synthetic antioxidants. Mentha aquatica (water mint) is a perennial medicinal and aromatic herb in the genus Mentha, which produces a large and diverse group of phenolic constituents. In this study, Mentha aquatique extracts by ultrasound assisted and maceration (ethanol: water (80:20)) extraction method were compared. The total phenolic, tocopherol,flavonoid and tannin content and antioxidant activity of the extracts was determined and compared with TBHQ by DPPH assay, β-carotene bleaching method and rancimat test. The results showed that the extract from ultrasonic treatment with high amount of phenols (51.92 mg gallic acid/g extract, tocopherols (6.55 mg α-tocopherol/ g extract), flavonoid (30.33 mg quercetin/ g extract) and tannin (10.25 mg catechin/ g extract). The antioxidant activity of extracts (50, 100, 250, 500, 1000 and 1500 ppm) were increased by increasing in concentration of extract. At 1000 ppm of concentration there was not observed significant statistical different (P<0.05) between TBHQ and both extracts. According to the results of antioxidant activity and of extract it can be said that both of Mentha aquatique extract could be a good alternative for synthetic antioxidant such as TBHQ and the ultrasound extraction method is preferred due to the use of lower solvent and time than the maceration method.