Preparation and anti-fatigue activity of polypeptides from sea cucumber viscera.

Background: In the industrial processing of sea cucumbers, the nutrient-rich viscera are often discarded as by-products, leading to resource waste and environmental pollution. To achieve high-value utilization of these resources, the present study aimed to optimize an enzymatic process to extract anti-fatigue bioactive peptides from sea cucumber viscera for use in functional foods.

Results: The hydrolysis conditions with neutral protease were optimized using response surface methodology and the optimal conditions were determined as follows: an enzyme addition of 3 μL g^-1, a temperature of 65 °C, pH 7.0, a duration of 4 h and a material-to-liquid ratio of 1:4 (g mL^-1). Under these conditions, a high polypeptide yield of 303.0 mg g^-1 was obtained. The resulting enzymatic hydrolysate (EH) contained small peptides (< 1000 Da) at a concentration of 775.40 mg g^-1, which was significantly higher than that in the non-enzymatic hydrolysate (491.21 mg g^-1). Furthermore, the EH exhibited increased levels of branched-chain and functional amino acids along with improved nutritional indices. The anti-fatigue effects of EH were evaluated in a murine model using an exhaustive swimming test combined with biochemical analyses. The results demonstrated that EH treatment significantly prolonged thorough swimming time and elevated levels of liver glycogen, lactate dehydrogenase, tumor necrosis factor-α and interleukin-2, at the same time as reducing blood urea nitrogen levels.

Conclusion: Bioactive peptides derived from sea cucumber viscera exhibit strong anti-fatigue activity, demonstrating great potential as functional food ingredients. This work provides a sustainable and efficient strategy for valorizing seafood processing by-products. © 2025 Society of Chemical Industry.