Intra-combined antioxidant activity and chemical characterization of three fractions from Rhamnus alaternus extract: Mixture design

The look for benefits antioxidant agents has attracted much attention from consumers, health and food industries. Certainly, the interactions occurring between different compounds affect the antioxidant efficiency. The current study aims the investigation of the antioxidant combined effect of Rhamnus alaternus fractions using DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay. The three most active fractions were subject for binary and ternary combinations using the augmented simplex-centroid design. Two known compounds emodin (1) and kaempferol (2) were identified from the ethanolic extract of the leaves of Rhamnus alaternus. Their structures were elucidated using spectroscopy data. The antioxidant potent of the crude extract and the mixture was compared with the antioxidant activity of the fractions separately. Important synergetic effects were observed in binary mixture between the most active fractions, besides the response optimizer allowed us to optimize the mixture presenting the highest antioxidant activity at 82.54 %. The results from the present work could have interesting applications in both medical formulations and functional food design.