Identification of peptides released from flaxseed (Linum usitatissimum) protein by Alcalase® hydrolysis: Antioxidant activity

Abstract

In this study, the hydrolysis of a flaxseed protein isolate with Alcalase ® was performed as a strategy to generate antioxidant peptides. A chromatographic separation of the hydrolysate was conducted by RP-HPLC. Both hydrolysate and six collected fractions were subjected to ORAC and FRAP assays to evaluate their antioxidant capacity. The higher antioxidant values were shown by fractions containing predominantly low molecular weight peptides, as it was demonstrated by MALDI analysis. Four peptides were identified by LC-MS/MS and one by Edman degradation. The peptide with sequence GFPGRLDHWCASE was synthesised showing a notable ORAC activity, 3.20 µmol Trolox equivalents/µmol of peptide. This value was higher than that reported for butylated hydroxyanisole. Therefore, the contribution of this peptide to the activity of the fraction where it had been found was 61%. The identified sequences represent an advance in the molecular characterization of the flaxseed protein fraction.

Intake of Protein Hydrolysates and Phenolic Fractions Isolated from Flaxseed Ameliorates TNBS‐Induced Colitis

“…Recently, Chalamaiah and colleagues have suggested that the immunomodulatory activity of food‐derived peptides is more related to length (2–10 residues) and to hydrophobic nature. These findings are consistent with our data, since we have demonstrated in a previous study that 70% of FPH are composed of peptides ranging from 500 to 1500 Da and hydrophobic amino acids represented 34.7% of the total amount of amino acids. Possibly, these properties might increase the solubility of the peptides in lipids, facilitating a better binding of these peptides to receptors on the surface of immune cells that could inhibit proinflammatory responses of immune cells in contact with bacterial components such as LPS.…”

“…In a previous paper, we indicated that FPH and phr‐FPH are composed mainly of peptides, but only FPH contains SDG and p‐coumaric, caffeic, and ferulic acids . The similarity among inhibitory activities of FPH and phr‐FPH indicates that there was no synergistic effect between peptides and phenolic compounds present in these samples.…”

“…In general, Phh has the highest FRAP and ORAC values while phr‐FPH has the lowest FRAP and ORAC values. Such differences may be related to their different direct action as free radical scavengers, since Phi and Phh are composed mainly of phenolic compounds while FPH and phr‐FPH are composed mainly of peptides . As antioxidant compounds, the anti‐inflammatory activity of these flaxseed samples may be explained by their ability to neutralize reactive oxygen species (ROS).…”

“…In a previous paper, our group demonstrated that the antioxidant capacity of FPHs and phenolic compounds was maintained or increased after a simulated gastrointestinal digestion, suggesting that these samples may exert a protective role against the reactive species in the intestinal tissue . Thus, the first aim of the present study was to evaluate the inhibitory capacity of FPHs and phenolic fractions on the production of inflammatory mediators by stimulated macrophages.…”

Characterization of protein hydrolysate from silkworm pupae (Bombyx mori)

“…The highest percentage of amino acid found in raw silkworm pupae was for glutamic acid (13.49%) and the percentage of glutamic acid increased after enzymatic hydrolysis. Amino acid profiles are an important factor affecting the antioxidant capacity of protein hydrolysate (Silva, Hernández‐Ledesma, Amigo, Netto, & Miralles, ). In the current study, the protein hydrolysate from silkworm pupae contained 3.73%–5.35% histidine, 4.32%–5.00% tyrosine, and 8.08%–8.52% lysine (Table ).…”