Angiotensin-Converting Enzyme 2 Activation Is Not a Common Feature of Angiotensin-Converting Enzyme Inhibitory Peptides

Abstract

Angiotensin-converting enzyme (ACE) catalyzes the formation of angiotensin II (Ang II), a vasoconstrictor, whereas its homologue ACE2 degrades Ang II into angiotensin (1–7) (Ang (1–7)), a vasodilator. Given the similarities in structure and their interconnected roles in the regulation of cardiovascular system, this study aims to investigate if ACE-inhibitory (ACEi) peptides can also activate ACE2. About 200 potent ACEi peptides were subjected to molecular docking, 20 peptides were selected for cell and in vitro enzymatic activity studies, and 5 peptides were fed orally to spontaneously hypertensive rats at a dose of 15 mg/kg body weight/day for 7 days. Peptides IKW and RIY showed significant antihypertensive activity with activated circulating/aortic ACE2, circulating Ang (1–7), and decreased Ang II levels. IQY reduced blood pressure, increased Ang (1–7) level, but did not affect ACE and ACE2. Peptides MAW and MRW did not affect blood pressure, ACE, and ACE2. Our study showed that ACE2 activation is not a common feature of ACEi peptides.

Two Novel Angiotensin-Converting Enzyme (ACE) Inhibitory and ACE2 Upregulating Peptides from the Hydrolysate of Pumpkin (Cucurbita moschata) Seed Meal

“…In this study, SNHANQLDFHP could significantly increase the activity of ACE2 in EA.hy926 cells at the concentrations of 100−500 μg/mL, and PVQVLASAYR displayed a similar effect at the concentration of 500 μg/mL (p < 0.05) as depicted in Figure 6D. However, activating ACE2 activity is not a common feature of ACE inhibitory peptides as confirmed in the study by Wang et al, 48 which found 8 (IQP, YQY, MRW, RIY, IKP, FFY, AKK, and IEF) out of 20 selected ACE inhibitory peptides had no effects on ACE2 levels. Although peptides with ACE inhibition activity had been previously identified from pumpkin seed proteins, 17,19,20 SNHANQLDFHP and PVQVLASAYR obtained in this study were the first PSM-derived peptides reported to have both ACE inhibition and ACE2 upregulation activities in endothelial cells.…”

Bioavailability and Metabolism of Bioactive Peptide IRW with Angiotensin-Converting Enzyme 2 (ACE2) Upregulatory Activity in Spontaneously Hypertensive Rats

“…Another example is MRW, derived from Rubisco, which effectively lowers the blood pressure in SHRs. Unlike IRW, MRW achieves its blood pressure-lowering activity through prostaglandin D2-dependent vasorelaxation rather than ACE2 upregulation. , These findings collectively suggest the novelty of peptide IRW.…”

“…The aorta is a potential target of ACE2 upregulatory peptides, including IRW. , Therefore, the aortic ACE2 levels in SHRs treated with IR and tryptophan were assessed. As shown in Figure , tryptophan treatment significantly increased ACE2 protein levels, with a p value of 0.011.…”

“…The SHRs used in the bioavailability study underwent a 2 week recovery period to eliminate the interference of peptide IRW. Afterward, SHRs were surgically implanted with telemetry transmitters (HD-S10, Data Sciences International, St. Paul, MN, USA) as previously described. , Briefly, the transmitter was placed in the left groin area, and the catheter was inserted into the femoral artery and then advanced to the abdominal aorta. After surgery, rats were allowed for one-week postoperative recovery and injected with buprenorphine for pain relief in the first 3 days.…”

“…Cells grown on 6-well plates were incubated with IRW (50 μM), tryptophan (50 μM), or kynurenine (0.4 mM) for 24 h. After the removal of the culture medium, the cells were lysed by boiling Laemmli’s buffer with 2% DTT. In addition, protein extraction from the rats’ aorta was performed using the RIPA buffer, following the previously outlined steps . Then, the prepared samples were loaded onto a 9% SDS-PAGE gel, transferred to a nitrocellulose membrane, blocked using 5% BSA in TPBS (PBS buffer with Tween 20), and incubated overnight with primary antibodies against ACE2 and GAPDH.…”