Abstract:

This work reports the application of single factor experimental design and response surface methodology to
optimize conditions for enzymatic hydrolysis of the intestinal tissue of Apostichopus japonicas and the protective effect
of the resulting peptides on primary macrophages of mice from injury caused by hydrogen peroxide. Hydrolysates were
fractionated by ultrafiltration membranes with different cut-off molecular weights (MWCO). The cell viability was detected
by MTT (3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide) assay. Results showed that the highest degree of
hydrolysis of 41.82% was attained after 2.84 h of hydrolysis at 50.10 ℃ with 26 390 U of papain. Peptides with molecular
mass less than 650, 650–1 000 and 1 000–10 000 u were separated by ultrafiltration, and they all could significantly increase
the viability of primary cells and show a protective effect against hydrogen peroxide-induced injury. Furthermore, the
peptide with molecular mass less than 650 u showed better protective capacity.

Key words: Apostichopus japonicus intestinal tissue, enzymolysis, response surface analysis, ultrafiltration, hydrogen peroxide-induced injury