Trends in the Promising Functional Pigment, Phycocyanobilin: Preparation, Health Benefits, and Utilization.

Phycocyanobilin (PCB) is a linear tetrapyrrole chromophore covalently bound to phycocyanin that is widely distributed in cyanobacteria and certain microalgae. PCB has attracted increasing attention, because of its well-defined structure, excellent biocompatibility, and diverse bioactivities. It is primarily derived from natural algae extracts, while metabolic engineering enables heterologous biosynthesis for future, scalable production. Accumulating evidence indicates that PCB exhibits potent antioxidant, anti-inflammatory, and other activities, primarily through free radical scavenging and modulation of signaling pathways, such as nicotinamide adenine dinucleotide phosphate oxidase and nuclear factor erythroid 2-related factor 2. However, the practical application of PCB remains limited by environmental factors, as well as by industrial-scale expansion and regulatory constraints. This review provides a comprehensive synthesis of preparation strategies, bioactivities, stabilization, and delivery approaches and applications of phycocyanobilin, while also addressing current challenges related to processing adaptability and industrial applications to support the high-value development of algae-derived functional pigments.