Protective effects of Sacha inchi meal protein hydrolysate against oxidative stress and endothelial dysfunction via MDA suppression and SOD activation in L-NAME-induced hypertensive rats

Endothelial dysfunction and oxidative stress are central contributors to hypertension. Sacha inchi meal protein hydrolysate (SIPH) is recognized for its strong antioxidant activity and potential cardiovascular benefits. This study investigated the protective effects of SIPH on endothelial function and oxidative stress in rats with L-NAME (LN)-induced hypertension. Acute oral toxicity testing showed an LD₅₀ greater than 5000 mg/kg, classifying SIPH as low hazard (Category 5). Male Sprague-Dawley rats received LN (40 mg/kg) and were treated orally with SIPH (100, 300, or 500 mg/kg), captopril (5 mg/kg), or SIPH (500 mg/kg) combined with captopril (2.5 mg/kg) for five weeks. Blood pressure was monitored weekly and validated by carotid artery cannulation. Endothelial function was assessed by vasorelaxation responses to acetylcholine (ACh) and sodium nitroprusside (SNP) in isolated aortic rings, while serum malondialdehyde (MDA) and superoxide dismutase (SOD) activity were measured as markers of oxidative stress. LN administration elevated blood pressure impaired ACh-induced vasorelaxation, increased MDA, and reduced SOD activity. SIPH at 500 mg/kg significantly reduced blood pressure, restored endothelial-dependent relaxation, decreased lipid peroxidation, and enhanced antioxidant defense. Notably, the combination of SIPH with captopril exerted synergistic antihypertensive effects, producing greater improvements in vascular reactivity and oxidative balance than either treatment alone. These findings demonstrate that SIPH is a potent vascular protector, acting through synergistic antihypertensive, vasodilatory, and antioxidant mechanisms. Its properties position SIPH as a promising natural dietary intervention for mitigating hypertension and preserving endothelial function.