Chemical composition and immunomodulatory effects of enzymatic protein hydrolysates from common carp (Cyprinus carpio) egg

Objectives: The aim of this study was to prepare protein hydrolysates from underutilized common
carp (Cyprinus carpio) egg and to investigate their immunomodulatory effects in vivo.
Methods: Common carp (Cyprinus carpio) egg (roe) was hydrolysed by pepsin, trypsin, and Alcalase.
Chemical composition (proximate, amino acid, mineral and fatty acid compositions) and molecular
mass distribution of the three hydrolysates were determined. The carp egg protein hydrolysates
(CEPHs) were evaluated for their immunomodulatory effects in BALB/c mice. CEPHs (0.25, 0.5 and
1 g/kg body weight) were orally administered daily to female BALB/c mice (4–6 wk, 18–20 g) for a
period of 45 d. After 45 d, mice were sacrificed and different tissues were collected for the
immunologic investigations.
Results: The three hydrolysates contained high protein content (64%–73%) with all essential amino
acids, and good proportion of u-3 fatty acids, especially docosahexaenoic acid. Molecular mass
analysis of hydrolysates confirmed the conversion of large-molecular-weight roe proteins into
peptides of different sizes (5–90 kDa). The three hydrolysates significantly enhanced the prolif-
eration of spleen lymphocytes. Pepsin hydrolysate (0.5 g/kg body weight) significantly increased
the splenic natural killer cell cytotoxicity, mucosal immunity (secretory immunoglobulin A) in the
gut and level of serum immunoglobulin A. Whereas Alcalase hydrolysate induced significant in-
creases in the percentages of CD4þ and CD8þ cells in spleen.
Conclusions: The results demonstrate that CEPHs are able to improve the immune system and
further reveal that different CEPHs may exert differential influences on the immune function. These
results indicate that CEPHs could be useful for several applications in the health food, pharma-
ceutical, and nutraceutical industries.