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

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  = 48.2 µm) and ABTS (IC₅₀  = 12.7 µm) scavenging and α-glucosidase inhibitory (IC₅₀  = 58.5 µm) properties of gallic acid by several folds (5.5, 3.6 and 2.7 folds; IC₅₀  = 8.79, 3.51 and 21.5 µm, respectively). Zn(II) conferred a potent dose-dependent glucose uptake activity (EC₅₀  = 9.17 µm) 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.