Purification, Identification, and In Silico Analysis of Anti-Obesity and Antidiabetic Peptides from the Red Seaweed Palmaria palmata

Abstract

This study investigates the anti-obesity and antidiabetic potential of P. palmata extracts produced through sequential enzymatic and alkaline treatments. Among the treatment groups, the extract treated solely with Alcalase® (Alc) demonstrated the highest protein content (10.11 ± 0.15%) and degree of hydrolysis (30.36 ± 0.77%), significantly outperforming other treatments (p < 0.05). The Alc extract also exhibited superior inhibitory activity against porcine pancreatic lipase and α-amylase, achieving the lowest IC50 for lipase (2.29 ± 0.87 mg.mL−1) and showing significant enzyme inhibition across all tested concentrations (p < 0.05). Ultrafiltration of the Alc extract revealed that peptide fractions < 1 kDa and 1–3 kDa were most effective in enzyme inhibition, with IC50 values of 3.25–3.55 mg.mL−1 for both lipase and α-amylase. Peptides were identified via LC-MS/MS analysis and database searching using SequestHT, resulting in 536 sequences, of which bioinformatic screening yielded 51 non-toxic, non-allergenic candidates (PeptideRanker score > 0.6); four of these contained known inhibitory motifs for lipase and α-amylase. Molecular docking confirmed strong binding affinities between these peptides and their respective enzymes, supporting their potential as natural enzyme inhibitors. These findings indicate the functional food potential of Alcalase®-derived P. palmata peptides for managing obesity and type 2 diabetes.