Extraction of hydroxy safflower yellow A and anhydroxysafflor yellow B from safflower florets using natural deep eutectic solvents: Optimization, biological activity and molecular docking

Abstract

This study established an eco-friendly natural deep eutectic solvent (NADES) extraction system for simultaneous recovery of hydroxysafflor yellow A (HYSA) and anhydroxysafflor yellow B (AHSYB) from Safflower florets. Through systematic NADES screening, urea-sorbitol (Ur:Sor, 1:1) demonstrated superior extraction efficiency, yielding 20.98 ± 0.18 mg/g HYSA and 10.79 ± 0.22 mg/g AHSYB under optimized RSM conditions (75 % H₂O, 30 min, 51 °C, 10 mL/g), representing 21 % and 34 % enhancements over conventional solvents. The urea-sorbitol extract has a strong free radical scavenging ability, with a 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging rate of 92 % ± 2.6 %; its ferric reducing antioxidant power (FRAP) reducing capacity is 0.72 ± 0.07, and it also has xanthine oxidase (XO) inhibitory ability (half maximal inhibitory concentration (IC₅₀) is 1.48 ± 0.06 mg/mL). Molecular docking studies showed that both HYSA and AHSYB effectively bind to the active site of XO. Molecular dynamics simulations indicated that these compounds are stable ligands, maintaining high stability during their binding dynamics with XO. The free binding energies of HYSA and AHSYB to XO were −54.72 and −50.51 kcal/mol, respectively. These results highlight the crucial role of NADES in improving the extraction yield and functional activity of bioactive compounds. The obtained compounds thus hold potential applications in the food industry.