No abstract

Four new inhibitory peptides for angiotensin I-converting enzyme (ACE), that is, MRWRD, MRW, LRIPVA, and IAYKPAG, were isolated from the pepsin-pancreatin digest of spinach Rubisco with the use of HPLC. IC(50) values of individual peptides were 2.1, 0.6, 0.38, and 4.2 microM, respectively. MRW and MRWRD had an antihypertensive effect after oral administration to spontaneously hypertensive rats. Maximal reduction occurred 2 h after oral administration of MRW, whereas MRWRD showed maximal decrease 4 h after oral administration at doses of 20 and 30 mg/kg, respectively. IAYKPAG also exerted antihypertensive activity after oral administration at the dose of 100 mg/kg, giving a maximum decrease 4 h after oral administration. IAYKP, IAY, and KP, the fragment peptides of IAYKPAG, also exerted antihypertensive activity. LRIPVA [corrected] did not show any antihypertensive effect at a dose of 100 mg/kg despite its potent ACE-inhibitory activity.

Objective Oxidative stress is integral to the development of endothelial dysfunction and cardiovascular disease. As NRF2 is a key transcription factor in antioxidant defense, we aimed to determine whether polymorphisms within the promoter region of the gene encoding NRF2 (NFE2L2) would significantly modify vasodilator responses in humans. Methods Associations between the – 653A/G (rs35652124), – 651G/A (rs6706649), and – 617C/A (rs6721961) polymorphisms within the NFE2L2 promoter and vascular function were evaluated in healthy African-American (n= 64) and white (n= 184) individuals. Forearm blood flow (FBF) was measured by strain-gauge venous occlusion plethysmography at baseline and in response to incremental doses of bradykinin or sodium nitroprusside. Forearm vascular resistance (FVR) was calculated as the mean arterial pressure/FBF. Results In African Americans, – 653G variant allele carriers had significantly lower FBF and higher FVR under basal conditions as well as in response to bradykinin or sodium nitroprusside compared with wild-type individuals (P< 0.05 for each comparison). In whites, although no significant associations were observed with the – 653A/G genotype, – 617A variant allele carriers had significantly higher FVR at baseline and in response to bradykinin or sodium nitroprusside compared with wild-type individuals (P < 0.05 for each comparison). The – 651G/A polymorphism was not associated with vasodilator responses in either racial group. Conclusion Polymorphisms within the NFE2L2 promoter were associated with impaired forearm vasodilator responses in an endothelial-independent manner, suggesting an important role of NRF2 in the regulation of vascular function in humans.