Measuring the potential antioxidant activity of methyl gallate: Molecular docking study

Abstract

Objectives: This study aims to obtain predictions of the interactions that occur between methyl gallate and various antioxidant receptors while comparing it with gallic acid as its parent compound. Materials and Methods: The protein crystal structures of several antioxidant receptors from several classes such as an oxidoreductase (PDB ID 1HD2, 3MNG, and 3NRZ), transferase (PDB ID 2HCK), and transport proteins (PDB ID 4JK4) were selected as receptors. Molecular docking was performed using methyl gallate and gallic acid as test ligands with AutoDock 4.2.6. The main parameters used were the free energy of binding as an affinity marker and amino acid residues to see the level of similarity of interactions. Results: Of the five receptors used, methyl gallate showed the highest potential antioxidant activity at the 3NRZ receptor (xanthine oxidase) with the free energy of binding value of −7.45 kcal/mol, with the whole receptor showing a negative value, indicating a spontaneous reaction occurs. Both the affinity and the interaction between methyl gallate and gallic acid are not too much different, meaning the potential for comparable antioxidant activity. Conclusion: Overall, methyl gallate shows the potential for the antioxidant activity that is not too different from that indicated by gallic acid. Keywords: Antioxidant, docking, gallic acid, methyl gallate, xanthine oxidase