Carrageenan oligosaccharides: A comprehensive review of preparation, isolation, purification, structure, biological activities and applications

Carrageenan, a kind of water-soluble linear sulfated polysaccharide with excellent stability and gel-forming properties, has been widely used in food and cosmetic industries. Carrageenan oligosaccharides, as the degradation products of carrageenan, possessed versatile physiological activities as well as other excellent properties such as their lower molecular weight, better water solubility and higher absorption efficiency. Additionally, the biological activities of carrageenan oligosaccharides are closely related to their structure, especially the number and position of sulfate groups. This review aimed to comprehensively summarize the methods of preparation, structural characteristics, and the biological activities of carrageenan oligosaccharides. The biological mechanisms underlying the health benefits of carrageenan oligosaccharides are also elaborated in order to provide guidance for application of carrageenan oligosaccharides as marine sources in pharmaceutical and agricultural industries.