Characterisation of Bioactive Peptides from Red Alga Gracilariopsis chorda

In this study, we studied the bioactive peptides produced by thermolysin hydrolysis of a water-soluble protein (WSP) from the red alga Gracilariopsis chorda, whose major components are phycobiliproteins and Ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCo). The results showed that WSP hydrolysate exhibited significantly higher ACE inhibitory activity (92% inhibition) compared to DPP-IV inhibitory activity and DPPH scavenging activity. The phycobiliproteins and RuBisCo of G. chorda contain a high proportion of hydrophobic (31.0-46.5%) and aromatic (5.1-46.5%) amino acid residues, which was considered suitable for the formation of peptides with strong ACE inhibitory activity. Therefore, we searched for peptides with strong ACE inhibitory activity and identified two novel peptides (IDHY and LVVER). Then, their interaction with human ACE was evaluated by molecular docking, and IDHY was found to be a promising inhibitor. In silico analysis was then performed on the structural factors affecting ACE inhibitory peptide release, using the predicted 3D structures of phycobiliproteins and RuBisCo. The results showed that most of the ACE inhibitory peptides are located in the highly solvent accessible alpha-helix. Therefore, it was suggested that G. chorda is a good source of bioactive peptides, especially ACE-inhibitory peptides.

Automated summary

In this study, we investigated the bioactive peptides produced from the red alga Gracilariopsis chorda through thermolysin hydrolysis of a water-soluble protein (WSP). The results showed that the WSP hydrolysate exhibited strong ACE inhibitory activity, indicating the potential of G. chorda as a source of ACE-inhibitory peptides. Two novel peptides (IDHY and LVVER) with promising inhibitory effects were identified, and their interaction with human ACE was evaluated through molecular docking. In silico analysis further revealed that the ACE inhibitory peptides were mainly located in the highly solvent accessible alpha-helix.