Release of Angiotensin I-Converting Enzyme Inhibitory Peptides from Flaxseed (Linum usitatissimum L.) Protein under Simulated Gastrointestinal Digestion.

Key Findings:

Peptides with angiotensin I-converting enzyme inhibitory (ACEI) activities are key molecules to reduce elevated blood pressure.  The paper presents information on the ability of flaxseed protein to generate ACEI peptides during GI digestion. The amino acids of flaxseed protein were found to be high in Asp, Glu, Leu, and Arg and comparable to that of soy.  ACEI activity was exhibited identifying the ability of flaxseed protein to release ACEI peptides during GI digestion. Protein in flaxseed may be partially responsible for its cardioprotective function.

ABSTRACT:

The scope of this study was to determine the ability of flaxseed (Linum usitatissimum L.) proteins to release angiotensin I-converting enzyme inhibitory (ACEI) peptides during simulated gastrointestinal (GI) digestion using a static (SM; no absorption in the intestinal phase) and a dynamic model (DM; simultaneous absorption of digested products in the intestinal phase via passive diffusion). Gastric and gastric + small intestinal digests of flaxseed proteins of both models possessed ACEI activity. The ACEI activity of the gastric + small intestinal digest in the DM (IC50 unabsorbed, 0.05 mg N/mL; IC50 absorbed, 0.04 mg N/mL) was significantly higher (p < 0.05) than that of the SM (IC50, 0.39 mg N/mL). Two peptides, alpha pentapeptide (Trp-Asn-Ile/Leu-Asn- Ala) and a hexapeptide (Asn-Ile/Leu-Asp-Thr-Asp-Ile/Leu) were identified in the most active ACEI fraction (0.51 kDa) of the absorbable flaxseed protein digest by de novo sequencing. (Author’s Abstract)