Identification of antihypertensive peptides from Eudrilus eugeniae (Kinberg, 1867): in vitro ACE-I inhibition and peptide profiling

Hypertension remains a major global health concern, highlighting the need for the development of safer and more efficacious antihypertensive agents. This study investigated the angiotensin-I converting enzyme (ACE-I) inhibitory activity of bioactive peptides derived from the African Nightcrawler earthworm, Eudrilus eugeniae (Kinberg, 1867) (E. eugeniae). Crude protein extracts were subjected to enzymatic hydrolysis using pepsin and pancreatin, followed by gel permeation chromatography for fractionation. Among the seven fractions, pooled fraction 6 (PF6), composed of peptides ranging from 917 to 1611 Da with 7–12 amino acid residues, exhibited the highest ACE-I inhibitory activity at 88.3% and an IC₅₀ of 86.76 µg/mL. Peptide sequencing via MALDI TOF-MS/MS identified key sequences containing proline and hydrophobic residues, which may contribute to ACE-I inhibition. These findings suggest that E. eugeniae is a promising natural source of antihypertensive peptides.