Two-phase solvent extraction of phenolics from Origanum vulgare subsp. glandulosum

Integration of solid-liquid and liquid-liquid extractions, SLE and LLE, respectively, for selective recovery of Origanum vulgare subsp. glandulosum phenolics was studied. A Two-Phase Solvent Extraction (TPSE) was performed by maceration at room temperature using a green biphasic solvent system and compared to Centrifugal Partition Extraction (CPE). Up to 69 % of phenolics were similarly recovered by both CPE and TPSE techniques using the ethyl acetate/acetic acid/water solvent system (EAW) in immiscible proportions while only 56 % of purity was reached using the conventional successive technique. Up to 19 g GAE/100 g DW of total phenolics were recovered by solid-liquid-liquid extraction (SLLE) while only 12 g GAE/100 g DW was isolated by using SLE with EAW organic phase. Comparing TPSE to organic and aqueous macerations conducted separately, a clear positive impact of combination was observed, namely more than 57 % and 83 % enhancement of the extraction yields, respectively. Such extracts exhibited a very strong antioxidant activity as shown by the antioxidant activity index (AAI) higher than 2.