Angiotensin-converting enzyme inhibitory and antioxidant peptides from digestion of larvae and pupae of Asian weaver ant, Oecophylla smaragdina, Fabricius

BACKGROUND: Mixed larvae and pupae of weaver ant (Oecophylla smaragdina) are widely used as an important food ingredient in regions of Thailand. They have high nutritional values and comprise 53% protein and 13% lipid. Peptides derived from food proteins have been shown to possess biological activities. RESULTS: Peptides derived from pepsin and trypsin digestion of these weaver ant larvae and pupae were purified based on angiotensin-converting enzyme (ACE) inhibitory and antioxidant activities, and their amino acid sequences were identified by liquid chromatography–tandem mass spectrometry (LC-MS/MS). In silico docking of peptides with ACE successfully predicted the inhibitory peptides as confirmed by their chemical synthesis. Two peptides with sequences of FFGT and LSRVP showed IC₅₀ values for ACE inhibition of 19.5 ± 1.7 and 52.7 ± 4.0 µmol L⁻¹, respectively. In addition, one potent antioxidant peptide with a sequence of CTKKHKPNC showed IC₅₀ values of 48.2 ± 2.1 µmol L⁻¹ for DPPH assay and 38.4 ± 0.2 µmol L⁻¹ for ABTS assay, respectively. CONCLUSION: These results indicate that proteins from larvae and pupae of weaver ants are potential sources of peptides with anti-ACE and antioxidation bioactivities.