Applications of Bioactive Compounds from Marine Microalgae in Health, Cosmetics, and Functional Foods

Marine microalgae have emerged as promising biofactories for the sustainable production of high-value bioactive compounds with significant applications in human health, cosmetics, and functional foods. This review offers a comprehensive overview of the primary classes of bioactives synthesised by marine microalgae, including polyunsaturated fatty acids, carotenoids, phycobiliproteins, peptides, sterols, polysaccharides, phenolic compounds, vitamins, mycosporine-like amino acids, and alkaloids. These compounds demonstrate diverse biological activities, such as antioxidant, anti-inflammatory, antimicrobial, anticancer, immunomodulatory, and photoprotective effects, increasingly validated through in vitro, and clinical studies. Their mechanisms of action and roles in disease prevention and wellness promotion are examined in detail, with an emphasis on pharmaceutical (e.g., cardiovascular, neuroprotective), cosmetic (e.g., anti-ageing, UV protection), and nutraceutical (e.g., metabolic and immune-enhancing) applications. The review also addresses critical challenges in strain selection, cultivation technologies, downstream processing, product standardisation, and regulatory approval. Simultaneously, emerging opportunities driven by synthetic biology, omics integration, and circular biorefinery approaches are transforming marine microalgae into precise platforms for next-generation bioproducts. By summarising current knowledge and future directions, this work underscores the essential role of marine microalgae in advancing the blue bioeconomy and tackling global sustainability challenges.