Abstract
Alcalase is the enzyme of choice to release antihypertensive peptides from amaranth proteins, but the hydrolysis conditions have not been optimized yet. Furthermore, in vivo assays are needed to confirm such a hypotensive effect. Our aim was to optimize the hydrolysis of amaranth protein with alcalase and to test in vivo the hypotensive effect of the hydrolysates. A response surface analysis was carried out to optimize the hydrolysis reaction. The response variable was the Angiotensin Converting Enzyme (ACE-I) inhibition. The hydrolysis degree was determined (free alpha-amino groups measurement). The optimized hydrolysate bioavailability was assessed in the sera of mice and the hypotensive effect was assessed in spontaneously hypertensive rats. Control groups were administered captopril or water. The optimized hydrolysis conditions were: pH = 7.01, temperature = 52 °C, enzyme concentration 0.04 mU/mg, and time = 6.16 h. The optimized hydrolysate showed a 93.5% of ACE-I inhibition and a hydrolysis degree of 74.77%. After supplementation, the hydrolysate was bioavailable in mice from 5 to 60 min, and the hypotensive effect started at 4 h in spontaneously hypertensive rats (p < 0.05 vs. water group). This effect was similar to the captopril hypotensive effect for the next 3 h (p > 0.05). The use of amaranth-optimized hydrolysates as hypotensive supplements or ingredient for functional foods seems feasible.
Highlights
Hypertension is a risk factor for developing cardiovascular diseases such as coronary heart disease, atrial fibrillation, and heart failure, among others [1,2]
We present an optimized amaranth protein hydrolysate, which could have a higher potential to inhibit angiotensin-I-converting enzyme (ACE-I) in vitro than that reported by others [6], and this could be attributed to the optimized process of hydrolysis with alcalase based on a response surface analysis
Fritz et al showed that amaranth hydrolysates obtained with alcalase have a higher percentage of ACE-I inhibition than those obtained with other proteolytic enzymes such as trypsin, chymotrypsin, pronase, and papain
Summary
Hypertension is a risk factor for developing cardiovascular diseases such as coronary heart disease, atrial fibrillation, and heart failure, among others [1,2]. Some food proteins contain peptide sequences with different functions, including antihypertensive capacity [3,4]. More than 60 amaranth antihypertensive peptides have been identified to date [5]. Different enzymes have been used to hydrolyse amaranth proteins, but the catalysis by alcalase (E.C. 3.4.21.62) releases the peptides with the highest capacity to inhibit the angiotensin-I-converting enzyme (ACE-I) (E.C. 3.4.15.1) [6]. ACE-I is involved in the vasoconstriction process and its inhibition in in vitro assays is a common approach in the search for molecules with
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