Marine-Derived Antioxidants: Therapeutic Potential in Oxidative Stress-Related Diabetes Management

Oxidative stress is a central mechanism in the onset and progression of diabetes mellitus and its micro- and macrovascular complications. Chronic hyperglycaemia increases the production of reactive oxygen species (ROS) through mitochondrial overload, the polyol pathway, advanced glycation end-product (AGE) formation and NADPH oxidase activation, while pancreatic beta cells are particularly vulnerable because they express low levels of antioxidant enzymes. Synthetic antioxidants have shown limited clinical benefit and raise safety concerns, which has renewed interest in natural products. The marine environment, with its extreme conditions of salinity, light, pressure and temperature, yields structurally unique metabolites with strong antioxidant activity. This review summarises the major marine-derived antioxidants relevant to diabetes, namely fucoxanthin, fucoidan, phlorotannins, astaxanthin and marine bioactive peptides. It discusses their sources, antioxidant mechanisms (direct radical scavenging, Nrf2/ARE activation, modulation of antioxidant enzymes and inhibition of carbohydrate-digesting enzymes), evaluation methods, and preclinical and clinical evidence. Challenges such as extraction yield, bioavailability, standardisation and sustainability are outlined, and future directions are proposed.