In this study, the potential use of donkey serum albumin (DkSA) hydrolysates prepared by tryptic hydrolysis as cancer inhibitor was investigated. DkSA was isolated and purified from donkey plasma by anion-exchange chromatography on Source 15Q. The DkSA hydrolyzed by trypsin was ultrafiltrated using ultrafiltration membrane with a molecular weight cut-off of 1 kDa to obtain peptides mixture (HPM). The HPM showed inhibitory effect on the proliferation of different cancer cells, including human leukemia HL-60 cells, liver hepatoma HepG2 cells and breast cancer MDA-MB-231 cells under different concentrations. One of the most effective inhibitions was observed toward leukemia HL-60 cells with a 50% inhibitory concentration (IC50) of 0.073 mg/mL. Further experiments confirmed that the HPM induced leukemia cell apoptosis, which was observed by transmission electron microscope. However, the HPM had no significant effect on cell cycle distribution. This study suggests that the peptides derived from DkSA could inhibit tumor cell proliferation.
Enzymatic degradation products of proteins have multiple functions and the hydrolysates have been applied to produce a variety of functional foods, especially in the application of plant protein hydrolysates. Recently, the application of animal protein hydrolysates is gradually developed, in particular, to be used to inhibit cancer cell proliferation. This study revealed for the first time that hydrolysates of donkey serum albumin by trypsin had a relatively high inhibiting capability in tumor cell proliferation. It was much more effective in inhibiting leukemia cells than inhibiting liver cancer cells and breast cancer cells. The effect suggested that the peptides derived from donkey serum albumin could be functional food for anticancer in the future.