Angiotensin I-Converting Enzyme Inhibitory Peptides from Snakehead Fish Sarcoplasmic Protein Hydrolysate

In this study, the angiotensin I-converting enzyme (ACE) inhibitory peptides were isolated from snakehead fish sarcoplasmic protein hydrolysates. Enzymatic hydrolysis of sarcoplasmic protein was performed using various commercial enzymes. The alcalase hydrolysate with the highest ACE inhibition activity was purified with gel chromatography and reversed phased high-performance liquid chromatography. The purified fractions were then subjected to electrospray ionization quadrupole-micro-time-of-flight mass spectrometry for amino acid characterization. Two novel ACE inhibitory peptides LYPPP and YSMYPP with IC50 values of 1.3 and 2.8 μM were identified, respectively. The pattern of ACE inhibition, resistance to hydrolysis by gastrointestinal proteases and cytotoxic potencies of isolated peptides were described. The results showed no cytotoxicity of peptides on human embryonic fibroblast cell line (MRC-5) and human hepatocarcinoma cell line (HepG2). Practical Applications Freshwater fish muscle proteins and their hydrolysates offer huge potential as novel sources of natural bioactive peptides with angiotensin I-converting enzyme (ACE) inhibitory activity. The present study revealed the identification of two strong ACE inhibitory peptides obtained from alcalase hydrolysis of snakehead fish sarcoplasmic protein. However, further studies are required to determine the in vivo antihypertensive activity of the purified potent ACE inhibitory peptides.