Mixed vegetal extracts are interesting target of new products as nutraceuticals, superior ingredients for the design of functional food, singular ingredients for cosmetics, etc. In this work the extraction of amixture of spinach and rosemary leaves (50 wt.% of each plant) was investigated in terms of its antioxidant activity, and compared with the extraction of the separate species. Phenolic diterpenes of rosemary andcarotenoids of spinach were target compounds due their recognized biological activities. Two different extraction techniques were applied, namely pressurized liquid extraction using hexane at two different temperatures (100 and 150◦C) and supercritical fluid extraction with pure carbon dioxide at 40◦C andtwo different pressures (20 and 30 MPa). For each extraction technique and conditions three differentraw materials were employed: spinach leaves, rosemary leaves and the mixture 50:50 of spinach androsemary leaves.The antioxidant activity of the samples produced was evaluated with the ABTS assay and showed tobe enhanced when the species are simultaneously extracted, with antioxidant values around 20% higherthan the values corresponding to mixing the extracts obtained by separate. A possible synergic effect between carotenoids and phenolic diterpenes was studied, although no specific synergic activity couldbe observed. However, the enhanced antioxidant activity could be attributed to a definite increase ofthe concentration of carnosic acid, which was observed in the samples produced by the simultaneous extraction

NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Supercritical Fluids. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in J. of Supercritical Fluids 82 (2013) 138– 145 DOI http://dx.doi.org/10.1016/j.supflu.2013.07.004

This work has been supported by project INNSAMED IPT-300000-2010-34 (subprogram INNPACTO) from Ministry of Scienceand Innovation (Spain) and project ALIBIRD-S2009/AGR-1469 from Autonomous Community of Madrid