Development of a sustainable extraction and storage stability of antioxidant and anticholinergic pressurized natural deep eutectic solvent extracts from Citrus reticulata leaves

The recovery of phenolic compounds from C. reticulata leaves using pressurized liquid extraction (PLE) combined with Natural Deep Eutectic Solvents (NaDES) employing Choline chloride:Glycerol (1:2 molar ratio) as NaDES was investigated for the first time. A Box-Behnken experimental design was carried out to observe the influence of time, temperature and % water in NaDES on the extraction of compounds with antioxidant and anticholinergic (AC) capacities and only with antioxidant capacity (A). Besides, optimum extracts were compared with PLE extracts obtained under the same extraction conditions but using ethanol/water (70:30, v/v). PLE-NaDES-AC extract obtained at 150°C during 25 min with 57.9% water in NaDES displayed the highest in vitro antioxidant and anticholinergic capacities and the highest number of different phenolic compounds identified by HPLC-IT-MS compared with the rest of extracts. Lower extraction temperature (64°C) was necessary for obtaining extracts with only antioxidant capacity. Besides, a forced stability study showed a high protection effect of NaDES on the degradation of antioxidant phenolic compounds compared to ethanolic extracts. Results indicated that the use of PLE-NaDES is a sustainable alternative to ethanolic PLE extraction for the recovery of stable bioactive phenolic compounds. • Development of a PLE-NaDES extraction method of polyphenols from tangerine leaves. • High extraction temperatures were necessary to obtain anticholinergic compounds. • Low extraction temperatures provided extracts with higher antioxidant capacity. • Optimal extract showed higher bioactive phenolic content than PLE ethanolic extract. • A high antioxidant degradation protection was observed when NaDES was used as solvent.