Determining the adsorption and desorption properties of flavonoids found in Eucommia ulmoides Oliv. leaves using macroporous resin and acetylcholinesterase inhibitor screening

Abstract

The adsorption and desorption properties of 12 resins containing flavonoid compounds found in Eucommia ulmoides Oliv. leaves (EUOL) extracts were investigated. The static adsorption and desorption, kinetic, adsorption, and thermodynamic properties of the adsorption of the flavonoids onto macroporous resins were determined. The HPD-300, NKA-9, and AB-8 resins exhibited a greater adsorption capacity and desorption characteristics. A pseudo-second-order kinetic model was suitable to characterize the kinetics of the adsorption of flavonoids onto the resins selected, and the diffusion of flavonoids was divided into three stages, with the boundary layer diffusion and intra-particle diffusion being the rate-controlling factors. The Langmuir model was found to be the best description of the adsorption behavior of flavonoids. Thermodynamic studies indicated that the adsorption of flavonoids was a physical, exothermic, and spontaneous process. The 60% ethanol eluted fraction from the NKA-9 resin column not only had the highest flavonoid content, but also possessed the strongest inhibitory effect on acetylcholinesterase. In addition, the degree of binding of the main flavonoid compounds found in the EUOL to acetylcholinesterase compounds was investigated via molecular docking technology. The results showed that the docking total score of isoquercetin and enzyme proteins were the highest, followed by kaempferol-3-O-rutinoside.