Ovotransferrin-depleted egg white hydrolysate reduces blood pressure in spontaneously hypertensive rats

Egg whites contain a variety of biologically active proteins and are a good source of bioactive peptides. Egg white hydrolysate prepared by thermoase (EWH) possesses antihypertensive effects. Our recent study showed that egg white proteins, after depleting ovotransferrin, also contained many angiotensin-converting enzyme (ACE)-inhibitory peptides after hydrolysis using thermoase. In the present study, we aimed to explore the antihypertensive effect of the ovotransferrin-depleted egg white hydrolysate prepared by thermoase (OD-EWH) in spontaneously hypertensive rats, using EWH as the reference. The animals were orally administered with either hydrolysate at a dose of 1 g/kg body weight/d over 9 d. OD-EWH treatment significantly reduced blood pressure to a comparable extent to EWH (p < 0.05). OD-EWH upregulated the aortic expression of angiotensin-converting enzyme 2 and Mas receptor and inhibited the renal ACE (p < 0.05), without affecting the aortic ACE as well as aortic and renal angiotensin II receptors. It also significantly (p < 0.05) enhanced the aortic expression of endothelial nitric oxide synthase and reduced vascular oxidative stress, despite failing to mitigate the inflammation in the aortas. OD-EWH might reduce blood pressure via the modulation of the renin-angiotensin system, endothelial dysfunction, and oxidative stress. These findings demonstrate the potential of OD-EWH as a functional food ingredient against hypertension.