Marine Carotenoids: A Critical Review of Bioactivities, Bioavailability, and Therapeutic Potential

The marine environment is a significant origin of bioactive substances like carotenoids. Marine carotenoids are secondary metabolites with mechanism-anchored benefits across redox, immune, and metabolic pathways, comprising antioxidant, anti-inflammatory, antidiabetic, anticancer, and antimicrobial activities. These bioactive compounds have garnered significant interest from the pharmaceutical, nutraceutical, and cosmetic industries, driving the exploration for novel natural reservoirs of carotenoids. However, most of the research has focused on carotenoids found in fruits, vegetables, and other higher plant components. Despite increasing interest, there are few publications on carotenoids found in marine sources such as seaweed, microalgae, and marine animals. This review summarizes chemistry, biosynthesis, extraction methods, bioavailability, and the bioactivities reported for major marine carotenoids (e.g., α- and β-carotene, lycopene, fucoxanthin, astaxanthin, zeaxanthin, canthaxanthin, spirilloxanthin, halocynthiaxanthin, neoxanthin, and peridinin).