Identification and theoretical explanation of chemical composition against α-amylase in the n-hexane extract from Sargassum fusiforme

Sargassum fusiforme is an edible alga that possesses a number of bioactivities , such as antidiabetic effects. In the present study, the n -hexane extract of S. fusiforme showed inhibitory activity against α-amylase. To interpret the α-amylase inhibitory activity of this extract, a method based on GC–MS and molecular docking was established. A total of 25 compounds were identified using GC–MS and then individually docked with α-amylase to simulate interactions between the latter and the ligands. Among the compounds determined, phenol, 2,2′-methylenebis[6-(1,1-dimethylethyl)-4-methyl- (PMDM) was completely enfolded in the active site of α-amylase via hydrophilic and electrostatic interactions, van der Waals forces, hydrogen bonds and π-π stacking interactions and showed the lowest binding energy (−6.25 kcal/mol). The activity of PMDM against α-amylase was further tested and verified in vitro, and its IC 50 was found to be 79.96 ± 0.34 μM. Thus, this compound is responsible for the α-amylase inhibitory activity of the n-hexane extract of S. fusiforme .