Purification and identification of an angiotensin I converting enzyme (ACE) inhibitory peptide from the gastrointestinal hydrolysate of the cotton leafworm, Spodoptera littoralis

Enzymatic hydrolysis of the protein from an edible insect species, the cotton leafworm Spodoptera littoralis (Lepidoptera) leads to the release of angiotensin I converting enzyme (ACE) inhibitory peptides. The subsequent hydrolysis with pepsin, trypsin and α-chymotrypsin was designed to simulate the human gastrointestinal digestion process. After fractionation of this hydrolysate using consecutive chromatographic techniques, including size exclusion chromatography and reverse-phase high-performance liquid chromatography, a new ACE inhibitory tripeptide was identified. The amino acid sequence of the tripeptide was determined as Ala-Val-Phe and the in vitro ACE inhibitory activity assay revealed an IC50 value of 2123 μM.