Antioxidant activities of plants enriched in rosmarinic acid

The present study aims to evaluate the in vitro antioxidant potential of Lavandula dentata and Mentha aquatica plant extracts. For that, ethanolic extracts of the two plants were prepared and their phenolic composition was determined through combined methods of HPLC-DAD and ESI-MS. Moreover, the antioxidant activity of the plant extracts was estimated by: i) evaluation of DPPH scavenging potential and ii) monitoring the protective effects against the generation of reactive oxygen species (ROS) induced by potassium dichromate in human hepatoblastoma HepG2 cells. M. aquatica ethanolic extract was much enriched in phenolic compounds, in comparison with that of L. dentata. Both extracts contained rosmarinic acid in similar concentrations but M. aquatica also contained significant amounts of other phenolics, including rutinoside derivatives of eriodictyol and luteolin. The plant extracts showed high radical scavenging activity against DPPH radical and significantly diminished intracellular ROS production under oxidative stress conditions. The latter protection was mostly evidenced in the L. dentata extract and was also observed for the rosmarinic acid used as reference. Attending that rosmarinic acid is a major phenolic component of L. dentata and M. aquatica ethanolic extracts, the present results suggest that this phenolic compound can be involved in the antioxidant properties of both plants