Antioxidant activates of new carbohydrate based gallate derivatives: A DFT study

•Antioxidant activity of Ga and two of its glucose based derivatives were studied using DFT method.•The antioxidant activity studied through BDE, SET-PT and SPLET mechanisms.•BDE mechanism is the best descriptor for evaluation of antioxidant activities.•Antioxidant activities do not reduce by derivation. Biocompatibility, biodegradability, low-cost and rich chemistry of carbohydrates is among the most important features that make them promising materials for biomedical applications. Nowadays many research focused on exploring new polymeric antioxidant based on natural and synthetic carbohydrates. In this context, the antioxidant activity of Gallic Acid (Ga), Glucose Gallate (GG) and Glucose conjugated gallic acid by inverse ester bond (GGI) as two types of glucose conjugated derivatives of gallic acid containing, respectively, electron with-drawing and electron-donating groups as model molecules for polysaccharide gallate were studied using DFT (density functional theory) method. The radical scavenging capability of the compounds was exploded through BDE, SET-PT and SPLET mechanisms. Moreover, the solvent effects on antioxidant activities were investigated. It found that BDE mechanism is the best descriptor for evaluation of antioxidant activities in both gas phase as well as in the presence of solvents and GG is the most reactive antioxidant compound. Also, it was concluded that the antioxidant activities do not reduce by derivation, dramatically. In addition to the above mentioned mechanisms, the HOMO and LUMO energies and electrostatic potential maps for the compounds were computed and applied to predict the antioxidant activity of the compounds.