Lipase immobilization on multi-walled carbon nanotubes used as a target fishing tool and followed by molecular docking technique to analyze lipase inhibitor from Robinia pseudoacacia L.

In this study, R. pseudoacacia flowers exhibited potential lipase (Aspergillus niger) inhibitory activity. To quickly explore the active compound, ligand fishing was adopted for screening the ligand from R. pseudoacacia flowers by lipase immobilized on magnetic polyamidoamine dendrimer-coated multi-walled carbon nanotubes. After ligand fishing, the target compound was separated purposefully by optimizing the separation conditions of high-speed counter-current chromatography (HSCCC). As results, kaempferol with the IC50 of 327.64 ± 15.33 μg/mL was separated and identified. The further molecular docking results indicated that kaempferol was interacted with amino acid residue in the active site of lipase through van der Waals force, hydrogen bonds and Pi-Pi T-shaped interactions, yielding the binding energy of − 6.43 kcal/mol. The present method not only revealed the lipase inhibitory substances in R. pseudoacacia, but also provided an effective means for the screening of other natural substances.