Screening enzymatic extracts of Palmaria palmata based on composition and bioactivity

This study evaluated enzymatic extracts of Palmaria palmata for protein, amino acid, and phenolic contents, as well as their bioactivity including in-vitro antioxidant (radical scavenging and metal ion chelation), antidiabetic (α-glucosidase inhibition), and anti-obesity (porcine pancreatic lipase inhibition) properties. Three proteases including Alcalase®, Flavourzyme®, and Formea® Prime (trypsin) were applied at concentrations of 1 %, 2 %, and 3 % of protein content in biomass (% dry weight). The proteases were also investigated combined with a polysaccharidase (Celluclast®), either simultaneously or sequentially. The highest protein content and recovery were achieved when Alcalase® and Flavourzyme® were applied together (17.29 ± 0.17 % and 54.64 ± 1.53 %, respectively). Alcalase® generally produced extracts with higher protein, essential amino acids, and phenolic contents. Formea® Prime contributed to higher radical scavenging activities, with the Alcalase® and Formea® Prime combination showing the best radical scavenging (IC₅₀ = 1.04 ± 0.32 mg mL⁻¹). However, the extracts exhibited limited metal chelation activity. The best α-glucosidase inhibition was observed with Formea® Prime (35.51 ± 2.98 %) and Alcalase® (26.16 ± 2.85 %) alone at 16 mg mL⁻¹. Extracts with higher arginine content generally showed greater lipase inhibition, with the highest inhibition seen in the Alcalase® and Flavourzyme® combination (44.23 ± 0.39 %). However, this extract was low in arginine concentration, suggesting the effect might be due to peptide-polyphenol interactions. Addition of Celluclast® did not enhance the properties of the extracts and, in some cases, reduced them. Principal component analysis (PCA) indicated that radical scavenging and anti-obesity properties are likely governed by protein and phenolic contents and specific amino acids.