The antioxidant capacity of an imidazole alkaloids family through single-electron transfer reactions

The single-electron transfer (SET) reactions from the neutral and mono-anion species of five imidazole alkaloids (lepidines A, B, C, D, and E) against hydroperoxyl radicals have been studied using the density functional theory and the Marcus theory. The deprotonated species of three alkaloids were found to have free radical scavenging activity. The antioxidant activity was studied via single-electron transfer (SET) under physiological conditions. The SET reactions for lepidines B, D, and E were found to have rate constants ranging from 10⁵ to 10⁶ M^-1 s^-1. Therefore, they are predicted to be able to deactivate hydroperoxyl radicals and therefore the damage caused by them to polyunsaturated fatty acids. It is important to mention that the acid-base equilibrium plays an important role in their free radical scavenging activity. Graphical abstract Lepidines are predicted to be able to deactivate hydroperoxyl radicals and the damage caused by them to polyunsaturated fatty acids.