Green seaweed Ulva spp. bioprocessing: Bioactive molecules, emerging extraction technologies, and industrial applications in the circular bioeconomy

Ulva spp., commonly known as sea lettuce, are versatile green macroalgae that offer strong potential for integration into emerging blue and circular bioeconomies. Ulva is a fast-growing and nutrient-tolerant species that produces renewable biomass rich in bioactive compounds with economic potential. This review summarizes advances in the characterization, extraction, and industrial utilization of Ulva biomass, highlighting opportunities for scalable biorefinery approaches. Key bioactive classes include sulfated polysaccharides (ulvans), proteins and peptides, polyunsaturated fatty acids, pigments, and phenolic compounds, which exhibit diverse antioxidant, antimicrobial, and anti-inflammatory properties. Recent developments in green extraction technologies, such as ultrasound-, microwave-, and enzyme-assisted methods, as well as supercritical fluids and deep eutectic solvents, have improved yields in processing Ulva biomass while reducing environmental impact. Beyond laboratory studies, industrial applications are expanding across the food, cosmetic, pharmaceutical, and biomaterial sectors, supported by growing interest in sustainable marine ingredients. However, challenges remain in biomass standardization, taxonomy, large-scale cultivation, and regulatory approval. Integrating Ulva within a circular bioeconomy requires harmonized methodologies and life-cycle assessments to ensure economic and environmental sustainability. Ulva spp. combine rapid growth, carbon capture, and a unique spectrum of bioactive compounds, making them a versatile and scalable marine feedstock for sustainable, circular biorefineries across food, health, and material applications.