Preparation, structure-activity relationship, biological activities and market applications of Isatis indigotica polysaccharides: A review

Isatis indigotica polysaccharides (IIPs), derived from the traditional Chinese medicinal herbs Banlangen (Radix Isatidis) and Daqingye (Folium Isatidis), have been used in Chinese medicine for over two millennia. Recent studies have identified IIPs as major bioactive components of Isatis indigotica, exhibiting a broad spectrum of biological activities, including antiviral, immunomodulatory, antioxidant, anti-inflammatory and hepatoprotective effects, as demonstrated by both in vitro and in vivo experiments. Extraction and purification methods significantly affect the molecular weight, monosaccharide composition, and glycosidic linkages of IIPs, which influence their biological activity. Moreover, structural modifications have been shown to enhance both the bioactivity and solubility of IIPs. This review systematically summarizes recent advances in the extraction and purification methods, structure–activity relationships, and biological functions of IIPs. In addition, a patent analysis of 261 related applications is presented to assess the current status and limitations of IIP research and industrial development. Overall, this review provides a comprehensive theoretical framework for future research and offers practical insights for the industrial application and innovation of IIPs.