Bioactivity-Guided Separation of Potential α-glycosidase Inhibitor from Clerodendranthus Spicatus based on HSCCC with Molecular Docking

Clerodendranthus Spicatus is a traditional Dais medi-edible plant and it has been proven to have good blood glucose-lowering efficacy. However, the material basis of Clerodendranthus Spicatus has not been clarified yet. Therefore, in this paper, the compounds were purified by high-speed counter-current chromatography (HSCCC) and the potential activity of compounds were determined by molecular docking. In the separation process, the solvent system was determined by a 9 × 9 map-based solvent selection strategy and the solvent system hexane/ethyl acetate/methanol/water (3:5:3:5, v/v) was used for HSCCC. Finally, five compounds were purified and identified as 2-Caffeoyl-L-tartaric acid (1), N-(E)-caffeoyldopamine (2), rosmarinc acid (3), Methyl rosmarinate (4), 6,7,8,3',4'-Pentamethoxyflavone (5). Then, the identified compounds were individually docked with α-glycosidase. The affinity energies of the identified compounds ranged from -7.6 to -8.6 kcal/mol, which are all better than acarbose (-6.6 kcal/mol). In particularly, rosmarinc acid with the lowest affinity energy of -8.6 kcal/mol was wrapped by the active site of α-glycosidase. The docking results indicated that the target compounds have potential α-glycosidase inhibitory activity and may be responsible for the blood glucose-lowering activity of Clerodendranthus Spicatus. The results indicated that the bioactivity-guided method is practical for the effective separation of active compounds from natural resources.