Anti-oxidant activity of 6-gingerol as a hydroxyl radical scavenger by hydrogen atom transfer, radical addition and electron transfer mechanisms

Mechanisms of anti-oxidant action of 6-gingerol as a hydroxyl radical scavenger have been investigated using the transition state theory within the framework of density functional theory. Hydrogen abstraction by a hydroxyl radical from the different sites of 6-gingerol and addition of the former to the different sites of the latter were studied. Electron transfer from 6-gingerol to a hydroxyl radical was also studied. Solvent effect in aqueous media was treated using the integral equation formalism of the polarizable continuum model (IEF-PCM). Reaction rate constants in aqueous media were generally found to be larger than those in gas phase. The tunneling contributions to rate constants were found to be appreciable. Our results show that 6-gingerol is an excellent anti-oxidant and would scavenge hydroxyl radicals efficiently.