Sulfated polysaccharides and metallothioneins from microalgae: a dual-platform model for next-generation pharmaceuticals

Microalgae are sustainable sources of structurally diverse biomolecules with growing pharmaceutical relevance. Among these, sulfated polysaccharides (SPs) and metallothioneins (MTs) have attracted increasing attention because of their diverse biological activities and stress-responsive biosynthesis. This review proposes an integrated SP–MT dual-platform concept, providing a conceptual framework for exploring how the complementary extracellular functions of SPs and intracellular protective roles of MTs may collectively inform future pharmaceutical research and biomanufacturing. Current knowledge on their biosynthesis, structural diversity, biological activities, and production technologies is critically evaluated. Experimental evidence demonstrates that SPs possess antiviral, anticoagulant, antioxidant, immunomodulatory, and anticancer activities, whereas MTs contribute to metal homeostasis, detoxification, redox regulation, and protection against oxidative stress. Although their co-induction under environmental stress provides a biological rationale for coordinated applications, evidence supporting synergistic therapeutic effects remains limited, and the proposed dual-platform concept requires rigorous experimental and clinical validation. The review also highlights recent advances in cultivation engineering, systems biology, synthetic biology, nanotechnology, and artificial intelligence that may accelerate the discovery, optimization, and standardized production of these biomolecules. The key priorities for future research include elucidating biosynthetic pathways, establishing structure–activity relationships, developing scalable manufacturing processes, and conducting comprehensive preclinical evaluation to support their future pharmaceutical translation.