Ultrasound-assisted preparation of ‘Ready-to-use’ extracts from Radix Paeoniae Rubra with natural deep eutectic solvents and neuroprotectivity evaluation of the extracts against cerebral ischemic/ reperfusion injury

•A ready-to-use NaDES extract of RPR was screened out of 27 NaDESs.•The extraction yields of ChCl-Sor was higher than conventional solvents.•Four in vitro antioxidant assays of the extracts were performed.•The extract can be directly used in vivo to attenuate cerebral I/R injury.