Isolation and characterization of a novel homopolysaccharide (SFP-1) from Sargassum fusiforme: Promising anti-osteoporosis activity by modulating adipo-osteogenic differentiation

Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone tissue, thereby increasing the risk of fracture. An increasing number of studies have focused on the discovery of anti-osteoporosis drugs derived from natural polysaccharides isolated from traditional Chinese medicines. In this study, a novel homopolysaccharide (SFP-1) was isolated from Sargassum fusiforme, a traditional marine Chinese medicine. The monosaccharide composition, FT-IR, methylation, GC–MS and NMR analyses revealed that SFP-1 was composed of α-D-Glcp-1→, →4,6)-α-D-Glcp-(1→, and →4)-α-D-Glcp-(1→. Additionally, its osteogenic activities were evaluated using C3H10 cells in vitro and zebrafish skull models in vivo. The results demonstrated that SFP-1 significantly inhibited adipogenesis and substantially alleviated intracellular lipid accumulation by down-regulating the expression of adipogenic transcription factors, such as PPARγ, FABP4, and FASN. Moreover, SFP-1 enhanced the osteogenic activity of C3H10 cells by up-regulating the expression of osteogenic factors comprising RUNX2, COL1A2, OCN, OSX, and SPARC. Furthermore, it also significantly increased bone mass in zebrafish skull models. These results collectively suggest that SFP-1 is a promising anti-osteoporosis drug that functions by modulating the balance of adipo-osteogenic differentiation.