Synthesis, characterization, antidiabetic and antioxidative evaluation of a novel Zn(II)-gallic acid complex with multi-facet activity.

Abstract

This study was done to synthesize a novel Zn(II)-gallic acid complex with improved antidiabetic and antioxidative properties. The complex was synthesized and characterized using Fourier Transform Infrared (FT-IR) and 1 H NMR. Cytotoxicity was evaluated using Chang liver cells and L6 myotubes. Radical scavenging and Fe3+ -reducing, as well as α-glucosidase, α-amylase and glycation inhibitory properties were measured. Glucose uptake was measured in L6 myotubes, while the complex was docked against glucose transporter type 4 (GLUT-4) and protein kinase B (PKB). Analysis showed that complexation occurred through a Zn(O4 ) coordination; thus, the complex acquired two moieties of gallic acid, which suggests why complexation increased the DPPH (IC50 =48.2µm) and ABTS (IC50 =12.7µm) scavenging and α-glucosidase inhibitory (IC50 =58.5µm) properties of gallic acid by several folds (5.5, 3.6 and 2.7 folds; IC50 =8.79, 3.51 and 21.5µm, respectively). Zn(II) conferred a potent dose-dependent glucose uptake activity (EC50 =9.17µm) on gallic acid, without reducing the viability of L6 myotubes and hepatocytes. Docking analysis showed the complex had stronger interaction with insulin signalling proteins (GLUT-4 and PKB) than its precursor. Data suggest that complexation of Zn(II) with gallic acid resulted in a complex with improved and multi-facet antioxidative and glycaemic control properties.