Mechanistic Insights into the Antioxidant and Pro-oxidant Activities of Bromophenols from Marine Algae: A DFT Investigation.

Abstract

Marine algae are a rich source of aromatic secondary metabolites, with bromophenols (BPs) receiving particular attention due to their health benefits. Despite extensive research on BPs, the understanding of their antioxidant potential, as well as their mechanisms of action at the molecular level, remains incomplete. This study utilized density functional theory (DFT) to systematically elucidate the antioxidant and pro-oxidant mechanisms of the main BP scaffolds under physiological conditions. It was found that BPs exhibit potent antioxidant capacity in both polar and lipid environments. In lipid media, the formal hydrogen transfer mechanism has been identified as the exclusive antiradical pathway. The position of bromine atoms significantly influenced the activity, particularly in scaffolds containing one hydroxyl group. However, no significant effect was observed in scaffolds with two hydroxyl groups. In water, monodeprotonated BPs showed key radical scavenging activity, with different mechanisms favored depending on the configuration of the hydroxyl groups. Additionally, BPs, particularly those bearing a catechol moiety, exhibit secondary antioxidant activity by reducing the production of hydroxyl radicals via the ascorbic acid anion pathway. These findings provide further validation of the potent antioxidant properties of BPs and shed light on their mechanism of action in physiological environments.