Antioxidant capacity and phenolic content of two Algerian Mentha species M. rotundifolia (L.) Huds, M. pulegium L., extracted with different solvents

Background It is important to consider the optimum conditions and processing factors (like solvent type) influencing activity of plant antioxidants for utilization in food and biological systems. Methods The antioxidant capacity and phenolic content of two Mentha species, namely, Mentha pulegium L. (MP) and Mentha rotundifolia (L.) Huds (MR), were studied and six solvent systems were used. The total antioxidant capacity of the mint species extracts was evaluated using phosphomolybdenum method and the free radical-scavenging capacity by 2,2-diphenyl-1-picrylhydrazyl radical-scavenging assay. Results The efficiency of the used solvents to extract phenols from the two species varied considerably. The highest total phenolic content was obtained from methanol extract of MP (25.3±1.3 mg GAE/gdw) and total flavonoid content from methanol extract of MR (10.1±0.1 mg QE/gdw). High phenol content was significantly correlated with high antioxidant capacity. The methanol extracts showed the highest radical scavenging activity. All the extracts showed variable antioxidant capacity by the formation of phosphomolybdenum complex. Acetone extract of MP and methanol extract of MR exhibited marked reducing power in this method. Conclusions Our findings identified the appropriate solvent for extracting MP and MR phenolics which might provide a rich source of natural antioxidants.