Enzymatic Protein Hydrolysates, and Ultrafiltered Peptide Fractions from Two Molluscs: var. (L.) and (M.), with Angiotensin-I-Converting Enzyme Inhibitory and DPPH Radical Scavenging Activities.

Context: Multifunctional food protein-derived peptides attract a great deal of research interest due to their health-promoting benefits. Particularly, peptides that have both antihypertensive and antioxidant properties are desired, since both effects can be synergistic in prevention of cardiovascular diseases.

Aim: The aim of this study was to investigate the angiotensin-I-converting enzyme (ACE) inhibitory and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of two species of the Nigerian periwinkles: and .

Methods: The ACE inhibitory and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of simulated gastrointestinal digestion (SGID) hydrolysates and ultrafiltered (UF) fractions of var. and were determined. Human SGID of the protein extracts of and was carried out using pepsin, trypsin, and chymotrypsin, and the hydrolysates were fractionated into two by centrifugal ultrafiltration. The ACE inhibitory and DPPH radical scavenging activities of the crude hydrolysates and UF fractions were tested. The UF permeates were observed to have relatively higher activities and was subjected to gel filtration chromatography on Sephadex G-50. The chromatographic fractions showed absorbance at 215, 225, and 280 nm and were assayed for DPPH radical scavenging activity.

Results: The inhibitory effect of the fractions on ACE activity was reported as the minimum concentration of extract that caused 50% of the inhibition (IC), where the IC values of UF permeate and UF retentate were 65.2 ± 6.4 and 301.9 ± 59.1 μg/ml, respectively, and that of UF permeate (TFUFP) and UF retentate were 54.93 ± 2.83 and 291.7 ± 8.6 μg/ml, respectively.

Conclusion: This study suggests the potential health benefits of consuming var. and in health maintenance.