Salmon Nasal Cartilage Proteoglycan: Exogenous Functionality Compared to Other Chondroitin Sulfates

Chondroitin sulfate (CS), a glycosaminoglycan (GAG) member, is a partially sulfated linear polysaccharide. CS covalently binds to core proteins to form chondroitin sulfate proteoglycans (CSPGs), which are ubiquitously distributed on the cell surface and within the extracellular matrix. Over the past two decades, CS/CSPG products derived from natural sources, such as bovine, porcine, and salmon, have garnered increasing attention worldwide as promising agents for cosmetics, pharmaceuticals, and nutraceuticals. This review explores the characteristics of salmon cartilage proteoglycan (sPG) in pharmaceutical and nutraceutical oral administration compared with other CS/CSPGs. sPG can be easily extracted as a safe, functional anti-inflammatory and analgesic agent. sPG and other CS/CSPGs are translocated outside the gastrointestinal tract after oral intake. However, the translocated amount is minimal, and the underlying mechanism remains unclear. In addition to the conventional narrative that CSPGs exert their effects after absorption or translocation, this review discusses the potential behavior of CS/CSPGs that are not absorbed and remain in the gastrointestinal tract. The interaction activity of the CS chain and regulatory effects of sPG on intestinal bacterial flora suggest the potential luminacoid nature of CS/CSPGs. These insights improve our understanding of the functionality of exogenous CSPGs and expand their potential therapeutic applications.