Biofunctional Potential of Sulfated Polysaccharides from the Visceral By-products of Phyllophorella kohkutiensis
Sea cucumbers have long been valued for their nutritional and pharmacological properties, yet their processing generates substantial viscera residues that remain undervalued and underexploited. This study aimed to isolate, characterize, and evaluate the bioactivities of polysaccharides extracted from the viscera of Phyllophorella kohkutiensis, designated as PKV. Compositional characterization and FTIR analysis indicated that PKV is a crude sulfated heteropolysaccharides preparation composed mainly of galactose (Gal), galacturonic acid (GalA), glucuronic acid (GlcA), fucose (Fuc), and N-acetylgalactosamine (GalNAc). PKV demonstrated dose-dependent angiotensin I-converting enzyme (ACE) inhibitory activity, with an IC50 value of 1.30 ± 0.23 mg/mL. In addition, PKV exhibited preliminary growth-inhibitory effects against Gram-positive bacteria, including S. aureus, B. subtilis, and K. rhizophila, and showed moderate antioxidant properties as indicated by DPPH and ABTS radical scavenging activities and ferric-reducing power. Thermogravimetric analysis showed a maximum decomposition temperature of 247°C, indicating relatively high thermal resistance under dynamic heating conditions. Collectively, these findings highlight P. kohkutiensis viscera, a common processing by-product, as a sustainable source of bioactive sulfated polysaccharides with potential applications in nutraceuticals and functional foods.