Antioxidant and antibacterial activities and composition of Brazilian spearmint (Mentha spicata L.)

Antioxidant and antibacterial activities and the composition of Brazilian spearmint (Mentha spicata) extracts were evaluated. They were obtained by maceration with methanol, acetone, and dichloromethane, and the essential oil was obtained by hydrodistillation. The antioxidant activity was determined by antioxidant activity index (AAI), and the antimicrobial activity was evaluated by the diffusion method and by determination of minimum inhibitory concentration against Staphylococcus aureus and Escherichia coli. Phenolic compounds were determined by the Folin-Cioucalteu method, and the essential oil composition was identified by GC/MS. The methanolic extract showed a higher content of total phenolic compounds and stronger antioxidant activity, while only the essential oil showed antibacterial activity. The major compounds of the essential oil were carvone (67%), limonene (14.3%), muurolene (2.3%), and myrcene (2.1%).