Optimization, identification and bioactivity of flavonoids extracted from Moringa oleifera leaves by deep eutectic solvent

Moringa oleifera leaves (MOL) attract extensive attention in agriculture, pharmaceutical and food industry because of its rich biological activity. In this study, ChCl/LA as one of the deep eutectic solvents (DESs) was selected to extract flavonoids from Moringa oleifera leaves (FMOL). The extraction rate of FMOL reached 54.8 mg/g. After separation of FMOL, its biological activities were systematically studied. The IC50 values of FMOL for DPPH radical, ABTS radical scavenging activity, FRAP and ORAC were 27.3 μg/mL, 41.2 μg/mL, 18.7 mg TE/g and 6008.4 mg TE/g, respectively, indicating FMOL had excellent antioxidant activity. FMOL not only had better antibacterial activity than the positive controls, but also had inhibitory activity to tumor cells. The IC50 values of FMOL on B16 cells, HCT116 cells and Hep G-2 cells were 530.7, 328.0, and 533.7 μg/mL, respectively. Nine flavonoid compounds were identified by UPLC-Q-Orbitrap MS/MS, and four of them were confirmed from MOL for the first time. Therefore, FMOL extracted by ChCl/LA had rich bioactive components and is expected to be used in food and pharmaceutical industries.