Abstract
Sargassum maclurei is a potential protein resource because of its high protein content and relatively balanced amino acid composition. To promote its usage in food, medical, or other industries, S. maclurei protein was hydrolyzed by pepsin and papain to obtain bioactive peptides. The S. maclurei protein hydrolysates (SMPHs) were purified using gel chromatography and reversed-phase high performance liquid chromatography (RP-HPLC), and 12 major fractions were obtained. The fraction D11 with the highest angiotensin I-converting enzyme (ACE) inhibition (61.59%, at 1 mg/mL) was subjected to liquid chromatography-mass spectrometry (LC-MS/MS) analysis, and about 17 peptides were identified, of which the RWDISQPY (1063.5 Da) was chosen to be synthesized based on in silico analysis. The RWDISQPY demonstrated high ACE inhibition ability (IC50: 72.24 μM) with competitive inhibition mode, and could effectively (p < 0.05) lower the systolic blood pressure and diastolic pressure of spontaneously hypertensive rats at the concentration of 150 mg/kg body weight. The results of the molecular docking simulation demonstrated that RWDISQPY could bind with the active sites S1 and S2 of ACE via short hydrogen bonds. Moreover, RWDISQPY showed acceptable endothelin-1 suppressing capacity (26.21% at 1.5 mg/mL). These results indicate that S. maclurei could be developed into functional foods such as antihypertensive products.
Highlights
The important role of angiotensin I-converting enzyme (ACE) in increasing blood pressure has been demonstrated in the past decades, as about 9.4 million patients die from hypertension worldwide every year and 1.6 billion people are suffering from high blood pressure [1]
S. maclurei protein hydrolysates (SMPHs) was 16.82% ± 2.31%, which was lower (p < 0.05) than that of tilapia skin gelatin hydrolysates and Pacific cod skin gelatin hydrolysates prepared by the same enzymes [2,9]
The results suggest that RWDISQPY has an antihypertensive effect on spontaneous hypertensive rats (SHR), which is in accordance with the predicted result by the AHTPDB databases (Table 1)
Summary
The important role of angiotensin I-converting enzyme (ACE) in increasing blood pressure has been demonstrated in the past decades, as about 9.4 million patients die from hypertension worldwide every year and 1.6 billion people are suffering from high blood pressure [1]. Reducing blood pressure to normal levels is crucial, and more attention has been focused on the effects of ACE-inhibitory substances. The use of ACE-inhibitory peptides derived from food sources is a more effective way to reduce blood pressure without unacceptable side effects [2]. Undesirable dietary habits are the first risk factor responsible for the development of hypertension and diet-related cardiovascular disease. The control and improvement of diet is the most important and economical option to achieve a desirable blood pressure-lowering effect [4].
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