Bioactivity of hydrolysates obtained from bovine casein using artichoke (Cynara scolymus L.) proteases

Abstract

The objective of this work was to obtain casein hydrolysates with aspartic proteinases present in extracts from the artichoke flower (Cynara scolymus L.) and evaluate their antioxidant, antimicrobial, and angiotensin-I converting enzyme (ACE) inhibitory activity in vitro. The casein hydrolysates produced by the action of C. scolymus had elevated antihypertensive and antioxidant activity due to their high hydrophobic peptide content (93.84, 96.58, and 90.54% at 2, 4, and 16 h of hydrolysis, respectively). Hydrolysis time and molecular weight (<3 kDa) had a significant influence on the hypertensive and antioxidant activity of the hydrolysates, which were greater at hydrolysis times of 4 and 16 h and corresponding to the <3 kDa fractions. The <3 kDa fraction of the 16 h hydrolysate had an ACE inhibitory activity with a half-maximal inhibitory concentration (IC₅₀) of 71.77 µg peptides per mL; DPPH and ABTS^•+ radical scavenging activities of 6.27 µM and 6.21 mM Trolox equivalents per mg of peptides, respectively; and iron (II) chelation activity with an IC₅₀ of 221.49 µg of peptides per mL. Antimicrobial activity against Enterococcus faecalis was also observed in the hydrolysates. From the peptide sequences identified in the hydrolysates, we detected 22 peptides (from the BIOPEP database) that were already in their bioactive form (AMKPWIQPK, AMKPWIQPKTKVIPYVRYL, ARHPHPHLSFM, DAQSAPLRVY, FFVAPFPEVFGK, GPVRGPFPII, KVLPVPQK, LLYQEPVLGPVRGPFPIIV, MAIPPKKNQDK, NLHLPLPLL, PAAVRSPAQILQ, RELEELNVPGEIVESLSSSEESITR, RPKHPIKHQ, RPKHPIKHQGLPQEVLNENLLRF, SDIPNPIGSENSEK, TPVVVPPFLQP, VENLHLPLPLL, VKEAMAPK, VLNENLLR, VYPFPGPIH, VYQHQKAMKPWIQPKTKVIPYVRY, VYQHQKAMKPWIQPKTKVIPYVRYL) and are reported to display antioxidant, antimicrobial, and ACE inhibitory activity. We also identified 12,116, 14,513, and 25,169 peptide sequences in the hydrolysates at 2, 4, and 16 h, respectively, that were contained in the primary sequence, and these are reported to display ACE inhibitory, antioxidant, dipeptidyl peptidase IV inhibition, antithrombotic, opioid, immunomodulation, antiamnesic, anticancer, chelating, and hemolytic bioactivity.

Keywords: angiotensin-I converting enzyme (ACE) inhibitor; antimicrobial; antioxidant; artichoke; casein bioactive peptide.