Antioxidant and antimicrobial activities of the essential oil and solvent extracts of Mentha pulegium L.

Abstract

We report the total phenolic (TPC; expressed as gallic acid equivalents, GAE, per milligram of dry extract weight) and the total flavonoid contents (TFC; expressed as quercetin equivalents, QE, per milligram of dry extract weight) and antimicrobial and antioxidant activities of the essential oil and hexane, diethyl ether, ethyl acetate and methanol extracts of Mentha pulegium L. (Lamiaceae) collected in Serbia. The total phenolic content was in the range of 129.43-388.29 ?g GAE/mg, while TFC ranged from 57.81 to 160.94 QE/mg; the highest TPC and TFC were found in the methanol extract. The antimicrobial activity (against five bacteria and two fungi species) of the essential oil and solvent extracts was assessed using disc-diffusion method. However, the studied samples demonstrated a poor antimicrobial potential. The antioxidant activity was screened using five different tests: 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid radical cation decolorization assay (ABTS), total reducing power (TRP), ferric reducing antioxidant power (FRAP) and cupric reducing antioxidant capacity assay (CUPRAC); the methanol extract showed the strongest antioxidant potential. The results of the different antioxidant assays were correlated mutually and with the total flavonoid and total phenolic contents (regression analysis and agglomerative hierarchical clustering).