Eight antihypertensive peptides from the protein hydrolysate of Antarctic krill (Euphausia superba): Isolation, identification, and activity evaluation on human umbilical vein endothelial cells (HUVECs)

In this report, eight antihypertensive peptides were isolated from protein hydrolysate of Antarctic krill (Euphausia superba) using ultrafiltration and chromatography consecutively, and their sequences were identified as Trp-Phe, Tyr-Arg-Lys-Glu-Arg, Tyr-Arg-Lys, Val-Asp, Tyr-Lys-Asp, Phe-Gln-Lys, Phe-Ala-Ser, and Phe-Arg-Lys-Glu. The IC50 values of Trp-Phe (0.32 +/- 0.05 mg/mL) and Phe-Ala-Ser (0.15 +/- 0.02 mg/mL) on ACE inhibitory activity were significantly (p <= .05) lower than those of the other six peptides. Furthermore, Trp-Phe, Tyr-Arg-Lys, Phe-Gln-Lys, and Phe-Ala-Ser did not only increase the nitric oxide (NO) concentration and decreased the content of endothelin-1 (ET-1) in the medium of human umbilical vein endothelial cells (HUVECs) in a dose dependent manner after 24 h, but also significantly reversed the decreased production of NO in the presence of 0.5 mu M norepinephrine and the effect of NE on ET-1 production. These results indicate that the isolated anti hypertensive peptides can correct the endothelial cell dysfunction induced by norepinephrine.