Recent Advances in Polysaccharides from Sophora flavescens Ait.: Extraction, Purification, Structural Characteristics, Pharmacological Effects, Structure-Activity Relationships, and Potential Applications

Ethnopharmacological relevance: Sophora flavescens Ait. (S. flavescens) is a classical traditional Chinese medicine (TCM) with a long history of clinical use for clearing heat, drying dampness, killing parasites, and promoting diuresis. In recent years, extensive studies have confirmed that S. flavescens polysaccharides (SFP) are a critical bioactive macromolecular component of this plant, exerting broad and significant multi-target pharmacological effects. However, a comprehensive understanding of their structural complexity and molecular mechanisms is required to overcome current hurdles in their clinical translation. Aim of the review: This review aims to offer a systematic summary of the recent progress in the extraction, purification, detailed structural characteristics, and various pharmacological activities of SFP. It further explores the structure–activity relationships and toxicological profiles, thereby laying a solid foundation for the future development and utilization of SFP in pharmaceutical applications. Materials and methods: Key terms including “Sophora flavescens Ait.”, “S. flavescens” and “Sophora flavescens Ait. polysaccharide” were systematically searched in databases such as PubMed, Web of Science, and Google Scholar (2000–2026) to ensure the comprehensiveness and accuracy of the retrieved literature. Results: Modern extraction methodologies, including ultrasound-assisted, enzyme-assisted, and microwave-assisted extraction, significantly enhance SFP yield and preserve bioactivity compared to conventional hot-water extraction. Structurally, SFP are highly heterogeneous macromolecules predominantly composed of glucose, galactose, arabinose, and xylose. The diverse biological activities of SFP are heavily dependent on their structure–activity relationships; notably, targeted chemical modifications like sulfation drastically amplify their receptor affinity and efficacy. Pharmacologically, SFP exhibit potent antioxidant, anti-inflammatory, immunomodulatory, antitumor, and hepatoprotective properties by modulating core cellular signaling pathways such as NF-κB and Nrf2, while maintaining a highly favorable safety and cytocompatibility profile.