Abstract

Dipeptidyl peptidase IV (DPP-IV) inhibitory peptides play an important role in the prevention of diabetes. However, knowledge of seaweed-derived peptides remains limited. In this study, we evaluated the DPP-IV inhibitory peptide from the in vitro and in silico digestion of red alga dulse in Japan. The phycoerythrin (PE) α- and β-chains, a major protein in red algae, were heterologously expressed in Escherichia coli, followed by simulated in vitro pepsin–trypsin digestion. In silico analysis was also conducted to predict DPP-IV inhibitory peptides from the amino acid sequence of PE. As a result, the peptide EVYR was identified, exhibiting an IC₅₀ value of 327 μM. Furthermore, EVYR was successfully quantified in pepsin–trypsin digestions of both dulse powder and its water extracted dulse protein, with contents of 41.3 ± 4.0 μg/100 mg and 386 ± 35 μg/100 mg, respectively. Sequence analysis revealed that EVYR is conserved among various red algal PE α-chain. In silico pepsin–trypsin digestion suggested that EVYR was released from all red algal PE tested. To our knowledge, this is the first report quantifying a bioactive peptide generated from algal digestion. These findings suggest that peptides released from dulse during digestion may serve as promising functional food ingredients for glycemic control.