An effect-based approach to identify α-amylase inhibitors from the essential oil of Zingiber officinale rhizome: Experimental and computational studies

Abstract

Numerous studies showed that ginger extracts have antidiabetic effects, but there hasn't been any research on the effect of ginger oil on α-amylase, a possible target for the management of diabetes. This work was designed to characterize the volatile compounds in ginger oil, to estimate the inhibitory potency of oil on α-amylase activity, to detect and identify the bioactive constituents in the oil, and study how the active compounds interact with the enzyme. Ginger oil was extracted by water distillation, and analyzed using GC techniques. The inhibition potency of oil against α-amylase was evaluated based on the colored starch-iodine reaction. A TLC-bioautography method was used to find and separate α-amylase inhibitors from the oil, and then GC methods were used to identify the separated bioactive constituents. Molecular docking was performed to study the binding mode among active constituents, and enzyme. The GC analyses of ginger oil showed the presence of fifty-one compounds with α-zingiberene (13.0%), geranial (12.5%), neral (9.4%), camphene (7.0%), and β-phellandrene (6.0%) as the primary components. The half-maximum inhibitory concentration value for α-amylase inhibition potency of the oil was 684.00 (648.50–721.40) μg/mL. α-Amylase inhibition-directed analysis of the oil led to the identification of α-terpineol as one of the active constituents. In addition to other interactions, α-terpineol forms a hydrogen bond with the catalytic residue Asp197 of α-amylase, according to in silico investigations. These findings show that ginger oil could be considered a potential source of α-amylase inhibitors with antidiabetic activity.