Angiotensin I-converting enzyme (ACE) inhibitory peptide derived from Tenebrio molitor (L.) larva protein hydrolysate

Short peptides from different sources have been proven to be very efficient inhibitors of angiotensin I-converting enzyme (ACE), an enzyme with a major role in the regulation of blood pressure. In order to obtain ACE-inhibitory peptides from Tenebrio molitor (L.) larva, enzymatic hydrolysis was performed using Alcalase. The hydrolysate (DH 20 %) with the highest ACE inhibition was fractionated into four peaks according to their relative molecular weight by gel filtration on Sephadex G-15. The IC50 value of peak 2 (with the relative molecular weight 180–500 Da) was 0.23 mg/mL, while it was 0.39 mg/mL of hydrolysate before fractionation determined by reversed-phase high performance liquid chromatography (RP-HPLC). Antihypertensive activity of peak 2 was proven by single oral administration to spontaneously hypertensive rats (SHR). Multiple dose oral administration (100, 200, and 400 mg/kg body weight) to SHR led to a significant decrease in blood pressure for peak 2. The reduction of systolic blood pressure even reached 27 mm Hg at 4 h post-administration at a dose of 400 mg/kg body weight. Additionally, further separation and purification of the ACE-inhibitory peptides from peak 2 were performed using RP-HPLC on C18 column. Then a novel peptide Tyr–Ala–Asn was identified by tandem mass spectrometry with an IC50 value of 0.017 mg/mL. The result of research indicates that Tenebrio molitor (L.) larva protein may be a suitable candidate to prepare ACE-inhibitory peptides which could be used for food industry and nutraceuticals.