Evaluation of the in vitro biological activity of protein hydrolysates of the edible red alga, Palmaria palmata (dulse) harvested from the Gaspe coast and cultivated in tanks

Abstract

The in vitro antioxidant activity and angiotensin-converting enzyme (ACE) inhibition potential of protein extracts of Palmaria palmata (dulse) red seaweed from the Gaspe coast (QC, Canada) were investigated. The effects of the algae geographical origin and cultivation conditions were also studied. The highest activity values were displayed by <10 kDa protein fraction hydrolyzed by chymotrypsin (HF) at concentrations as low as 0.1 to 5 mg mL−1. Algae harvested in Pabos (QC, Canada) were more biologically active than algae from Newport (QC, Canada), demonstrating, respectively, 67.74 ± 3.9 % and 49.10 ± 10.9 % ACE inhibition at a concentration of 5 mg mL−1. Algae collected in Newport, cultivated in tanks with or without nutrients (NC+, NC−), scored higher biological activity than algae grown in Newport (N) waters. The <10 kDa HF obtained from the algae batch NC+ demonstrated, through an oxygen radical absorbance capacity assay, the highest antioxidant value: 440.73 ± 43.21 μmol trolox equivalents g−1 at 0.4 mg mL−1. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with database searches, protein precursors such as protein ribulose-1,5-biphosphate carboxylase/oxygenase (RuBiSCo) enzyme, allophycocyanins and phycocyanins, were identified in <10 kDa HF (P, N, NC−, NC+). Results show that protein hydrolysates from P. palmata demonstrate a high potential as healthy and functional ingredients and identified proteins could be targeted for crop improvement.