Preparation of Mannich reaction modified magnetic adsorbent for separation and purification of total flavonoids from Lycium barbarum leaves

Flavonoids are important secondary metabolites, but their separation and enrichment are difficult due to low contents and complex active components. Poly(styrene-divinylbenzene)-based resins are widely used for the separation of natural products, however, they have low adsorption capacity and poor selectivity. To solve these problems, Mannich reaction modified magnetic poly(styrene-divinylbenzene) (MPM-MR) microspheres were synthesized, and used for the separation and purification of flavonoids from Lycium barbarum leaves. Compared with other flavonoids (such as kaempferol, quercetin, naringenin and rutin), MPM-MR exhibited higher adsorption capacity and better selectivity for myricetin, which reached 81.6 mg/g at 298.15 K. Sieving interactions, hydrogen bonds and π-π interactions mainly exist between the MPM-MR and the flavonoids. In addition, the materials showed good enrichment of total flavonoids from actual samples of Lycium barbarum leaves, which increased from 8.17% to 24.99%. The Mannich reaction-modified magnetic poly(styrene-divinylbenzene) would be a promising material for efficient capture of flavonoids from natural plants.