Mixture design as an innovative tool to optimize the antioxidant and antibacterial activity of moroccan essential oils: Clinopodium nepeta, Ruta montana, and Dittrichia viscosa

This investigation is intended to demonstrate the synergistic, antibacterial, and antioxidant activity produced by the combination of essential oils (EOs) from Moroccan Clinopodium nepeta (CNEO), Ruta montana (RMEO), and Dittrichia viscosa (DVEO) EOs. The phytochemistry profile, the antibacterial effect and the antioxidant ability of EOs were assessed separately. Then, an augmented-simplex-centroid design was used to optimize the antibacterial activity of EOs formulations against Escherichia coli (E. coli) and Micrococcus luteus (M. luteus). The mixture design was also used to maximize the radical scavenging activity and the ferric reducing antioxidant power. The results of this study revealed that the optimal combination against E. coli conformed to 25% RMEO, 50% CNEO, and 25% DVEO, while the optimal mixture estimated against M. luteus was adjusted by the binary combination of 36% RMEO and 64% CNEO. Furthermore, the optimal association expected for DPPH inhibition is 37% RMEO, 40% CNEO, and 23% DVEO, while the formulation of 30% RMEO, 38% CNEO, and 32% DVEO presented the maximal mixture to obtain the highest ferric reducing power. These data showed the effectiveness of EOs mixtures against resistant bacteria and their promising employment as natural antioxidant agents in foods.