Abstract: The nutritional components and molecular mass distribution of the peptides prepared from the eggs and body wall of Apostichopus japonicus were detected, and then their effects on spleen lymphopoiesis and immune function in mice were evaluated. Four peptides from the eggs and body wall of sea cucumber were prepared by enzymatic hydrolysis and crossflow ultrafiltration. Mouse spleen lymphocyte proliferation (SLP) in vitro in the presence of each of the peptides (10, 50, 100 and 500 μg/mL) was measured by the sulforhodamine B colorimetric method. Furthermore, mice were subjected to oral gavage with each of the four peptides at low, middle and high dosages (83.3, 166.7 and 500.0 mg/kg) for 30 consecutive days. Those given water were used as a control group. After the experiments, organ/body mass ratio, delayed-type hypersensitivity, T lymphocyte proliferation induced by concanavalin A, the number of antibodyforming cells, serum hemolysin formation, carbon clearance capability, chicken red blood cell phagocytosis by mouse macrophages and natural killer cell activity were measured. The results showed that EP1 and BWP1 (1–10 kDa) at 500 μg/mL had a significant effect on SLP. The crude protein contents of EP1 and BWP1 were 64.74 and 70.25 g/100 g, the total amino acids were 45.69 and 63.26 g/100 g, and the molecular mass distribution was 130–1 600 and 130–2 500 Da, respectively. After the mice were orally administered with different doses of the peptides for 30 days, both EP1 and BWP1 enhanced monocyte-derived macrophage phagocytosis; EP1 improved cellular immune function while BWP1 augmented humoral immune function. In summary, EP1 and BWP1 from the eggs and body wall from Apostichopus japonicus had immunoenhancing effects and could be developed as new immunomodulatory products.

Key words: Apostichopus japonicus eggs, peptide, molecular mass, immune function, mice