Rosmarinic acid was obtained from methanolic extract of Mentha piperita L. under a reflux condenser. The current study aimed to evaluate the in vitro antioxidant activities and rosmarinic acid levels of the methanol extracts of M. piperita. The analysis of the sample by high-performance liquid chromatography technique (HPLC) indicated that rosmarinic acid was present in high concentration 1.9 mg/mL in the extract. Purification was carried out by column chromatography to give 0.020 g from 1 g of crude extract, and then the antioxidant activity of purified rosmarinic acid was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH), H2O2 scavenging, and REDOX methods. It was revealed that the anti-oxidant potential of the rosmarinic acid extract was greater than 95% (at 100 µg/mL) for DPPH assay and 87.83% (at 100 µg/ml) for H2O2 scavenging assay. This study was performed by using a reflux methanolic extraction of M. piperita. This possible instructional technique proved to be a quick and successful method for retaining the antioxidant properties of rosmarinic acid. The rosmarinic acid content was determined using HPLC.
Keywords: Anti-oxidant; DPPH; H2O2; RA; Reflux; M. piperita.