From Marine Algal Bioactives to Scalable Applications: Integrating Extraction, Mechanisms, Delivery, Safety, and Commercial Translation

Marine algae are emerging as important biological resources for the discovery and development of bioactive compounds with applications across food, pharmaceutical, cosmetic, agricultural, aquaculture, environmental, and biotechnological systems. This review critically synthesizes current knowledge on macroalgae and microalgae as sources of sulfated polysaccharides, carotenoids, phenolic compounds, proteins, peptides, vitamins, mycosporine-like amino acids, and polyunsaturated fatty acids. Emphasis is placed on the relationship between algal source, cultivation conditions, compound structure, extraction strategy, formulation, and biological activity. Key mechanisms of action are discussed, including antioxidant defense, modulation of inflammatory signaling, inhibition of metabolic enzymes, antimicrobial and antiviral activity, interactions with the gut microbiota, and regulation of cell-cycle-related pathways. Recent progress in biotechnological production, green extraction, purification, analytical characterization, bioaccessibility, bioavailability, and delivery systems is evaluated in the context of real product development. The review further highlights the use of algal bioactives in functional foods, nutraceuticals, pharmaceuticals, cosmeceuticals, aquafeeds, crop biostimulants, and environmental remediation. Current limitations, including biomass variability, compound instability, limited human validation, regulatory complexity, safety concerns, and scale-up costs, are also addressed. Overall, marine algae provide a sustainable and multifunctional platform for developing bioactive products when discovery, processing, validation, and commercialization are integrated.