An In-vitro Investigation of Selected Biological Activities of Hydrolysed Flaxseed (Linum usitatissimum L.) Proteins

A study was conducted to determine bioactivities of flaxseed (Linum usitatissimum L.; variety: Valour) proteins and their hydrolysates. Isolated flaxseed proteins were treated with Flavourzyme® at different levels of enzyme to substrate ratio (E/S) and hydrolysis time. The unhydrolysed proteins and hydrolysates were studied for angiotensin I-converting enzyme inhibiting (ACEI) activity, hydroxyl radical (OH·) scavenging activity and bile acid binding ability. Flavourzyme catalysed hydrolysis generated hydrolysates with a 11.94–70.62% degree of hydrolysis (DH). The hydrolysates (0.67 mg/ml) had strong ACEI activity (71.59–88.29%). The maximum ACEI activity containing hydrolysate exhibited an IC50 of 0.07 mg/ml (E/S: 1.5; Time: 12 h; DH: 11.94%). The OH· scavenging activity of the hydrolysates (0.5 mg/ml) was 12.48–22.08% with an IC50 of 1.56 mg/ml in the sample possessing maximum activity (E/S: 47.5; Time 0.7 h; DH: 24.63%). Both these activities were greater in hydrolysates with lower DH and higher peptide chain length (PCL) than those with higher DH and lower PCL. Hydrolysed flaxseed proteins (0.67 mg/ml) had no bile acid binding ability. The unhydrolysed proteins had no ACEI or OH· scavenging activity but demonstrated bile acid binding ability.