Low molecular weight flaxseed protein-derived arginine-containing peptides reduced blood pressure of spontaneously hypertensive rats faster than amino acid form of arginine and native flaxseed protein

► Hydrolysis of flaxseed proteins with trypsin and pronase produced arginine-containing peptides. ► Electrodialysis–ultrafiltration led to isolation of an arginine-rich peptide fraction (ARG-PF). ► The ARG-PF exhibited in vitro inhibition of angiotensin converting enzyme and renin activities. ► The ARG-PF had faster hypotensive effects than native protein or amino acid form of arginine. Flaxseed protein isolate (FPI) contains high amount of arginine, which plays important physiological roles especially as nitric oxide precursor in the vascular endothelium. Arginine-rich peptides can be generated from FPI and used as a source of nitric oxide, which can produce in vivo vasodilatory effects during hypertension. Enzymatic hydrolysis of FPI with trypsin and pronase resulted in a hydrolysate that was fractionated using electrodialysis–ultrafiltration (EDUF). EDUF experiment resulted in migration of peptides to the anionic and cationic recovery compartments. Compared to FPI with 11% arginine, about one-third of the cationic fraction was composed of arginine. Thirteen potential peptide sequences were identified to be present in the cationic compartment of which 12 contained at least one arginine residue. None of the peptides identified from the anionic compartment contained arginine. Oral administration of the cationic peptides (200mg/kgbodywt.) to spontaneously hypertensive rats resulted in a more rapid decrease in systolic blood pressure when compared to similar amounts of FPI or the amino acid form of arginine. It was concluded that the rapid effect of the arginine-rich peptide product suggests faster rate of peptide absorption than amino acids and this may be exploited to provide fast relief from hypertension.