An enhanced extraction and enrichment phytochemicals from Rosa roxburghii Tratt leaves with ultrasound-assist CO2-based switchable-solvent and extraction mechanism study

• This paper developed a method for obtaining compounds from disused cili leaves. • The CO 2 -based switchable-solvent is recyclable and environmentally friendly. • The extraction mechanism was studied by density functional theory. • This green extraction and enrichment method was a promising alternative. An efficient and ecofriendly extraction and enrichment process from Rosa roxburghii Tratt leaves using a CO 2 -responsive switchable solvent with ultrasound assistance based on a N,N-dimethyl-cyclohexylamine (DMCHA)/water system was developed in this study. We applied single-factor experiments combined with a Box-Behnken design to obtain the best operation conditions. The optimal parameters were as follows: bubbling CO 2 rate of 40 mL/min, bubbling CO 2 time of 29 min, and ultrasound time of 11.5 min. The yields of representative roxburic acid, kajiichigoside F1, pomonic acid, catechin, epicatechin, kaempferol, rutin, and quercetin reached 1.31 ± 0.02, 1.89 ± 0.01, 1.62 ± 0.02, 0.56 ± 0.015, 1.24 ± 0.024, 0.074 ± 0.002, 0.13 ± 0.001, and 1.56 ± 0.028 mg/g, respectively. The eight phytochemical extraction efficiencies and contents increased observably compared with traditional extraction methods. This process could achieve 5 cycles of extraction without obvious loss. Moreover, the properties of SHS and their relationship with the eight compounds were investigated by density functional theory. This process is a promising alternative for industrial manufacturing.