Algal polysaccharides, known for their biodegradability and biocompatibility, show significant promise for biomedical applications. Chondrus crispus (CC), a red alga, is a rich source of these polysaccharides, and this study investigated their bioactivities following auto-hydrolytic degradation.Polysaccharides were extracted and hydrolyzed from C. crispus, and their molecular weight was determined using size-exclusion chromatography (SEC). Structural analysis was performed using Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopy. A reduction in molecular weight after hydrolysis confirmed the successful breakdown of larger polysaccharide chains into smaller fragments. To evaluate the biological activity of the hydrolyzed polysaccharides, RAW264.7 cells were used to assess proliferation, migration, nitric oxide (NO) production, and phagocytic activity. The effects of the polysaccharide fractions were also tested on HDF, HCT-116, and Caco-2 cell lines. Specifically, the inflammatory responses in Caco-2 cells were measured by analyzing cytokine expression tumor necrosis factor-alpha (TNF-α), transforming growth factor-beta 1 (TGF-β1) and the chemokine monocyte chemoattractant protein-1 (MCP-1). The hydrolyzed C. crispus polysaccharides significantly modulated inflammatory responses and promoted wound healing, as evidenced by enhanced scratch assays. The 24-h, 50 kDa polysaccharide fraction (CC-24h) inhibited the proliferation and migration of HCT-116 (colon cancer) cells, while the native polysaccharide fraction (CC-2A) at 0.5 μg/μL had no effect on cell proliferation within 24 h. Notably, CC-derived polysaccharides resulted in a substantial reduction in LPS-stimulated NO production (p<0.0001) in RAW264.7 cells after 24 h. Furthermore, HDF cell proliferation was significantly increased after treatment with CC-0 polysaccharides (p<0.0001), which had a molecular weight of approximately 2700 kDa. In contrast, treatment of Caco-2 cells with all polysaccharide fractions led to increased TGF-β1 expression, but the absence of TNF-α expression at 24 h, suggesting the safety of these fractions for future biomedical applications. Additionally, unhydrolysed polysaccharide fractions (at 0.13 μg/μL) showed no cytotoxic effects in Caco-2 cells over 24 h. These findings indicate that the bioactivity of C. crispus-derived polysaccharides is influenced by their molecular weight, with effects varying across different cell types. Given their potential for promoting wound healing and alleviating gastrointestinal issues, these polysaccharides have promising applications in the food, cosmetic, and pharmaceutical industries.

Keywords: Lambda carrageenan; NMR; FTIR; HPLC-SEC; Immunomodulatory; Pro-inflammatory cytokines; Anticancer.

Acknowledgment

This research was funded by Estonian Research Council grants PRG1808