Grass carp peptides hydrolysed by the combination of Alcalase and Neutrase: Angiotensin‐I converting enzyme (ACE) inhibitory activity, antioxidant activities and physicochemical profiles

Abstract

In this study, grass carp peptides were prepared by enzymatic hydrolysis of grass carp protein using the combination of Alcalase and Neutrase, and angiotensin-I converting enzyme (ACE) inhibitory activity in vitro, antihypertensive activity in vivo, antioxidant activities, and physicochemical properties of peptides achieved from grass carp protein were characterised after ultrafiltration and desalted processes using mixed ion exchange resins. The purified peptides exhibited strong ACE inhibitory activity (IC 50 = 105 lg mL À1 ), antihypertensive activity with the maximal drop for systolic blood pressure (SBP) of 43 mmHg at a dosage of 100 mg per kg body weight in spontaneously hypertensive rat (SHR), and antioxidant activities indicated by thiobarbituric acid-reactive substance values in a liposome-oxidising system, radical-scavenging activity and chelation of metal ions (Fe 2+ ). The molecular weight of peptides was <1000 Da. Compared to grass carp protein, the peptides separated from enzymatic hydrolysates possessed similar amino acid compositions, but contained higher concentrations of essential amino acids. Moreover, the peptides exhibited excellent solubility at a wide range of pH values from 2 to 10, and lower apparent viscosity than the protein. The peptides separated from enzymatic hydrolysates might be used as a promising ingredient in antihypertensive functional foods and nutraceuticals.

Antihypertensive and Angiotensin-I-Converting Enzyme (ACE)-Inhibitory Peptides from Fish as Potential Cardioprotective Compounds

“…In an in-vivo experimental setting, after two hours (h) treatment, tested grass carp material showed significant antihypertensive activity (43 mmHg systolic blood pressure (SBP) maximal drop at the dosage of 100 mg kg −1 body weight (BW)) in SHR compared to the control group [42]. Grass carp peptides of size 725–1228 Da, rich in leucine, aspartic acid, phenylalanine and glycine amino acids, at 100 mg kg −1 BW in SHR 6 h post-administration significantly reduced SBP of approximately 30 mm Hg, in comparison to the control group (captopril), the medication of choice, with similar effect at dosage of 10 mg kg −1 BW) and the effect persisted for several weeks after the initial administration [43].…”

“…A clear example is that ACE-inhibition activity of jellyfish hydrolysate was enhanced by 8-fold (from IC 50 of 1.28 mg mL −1 to the low end of 0.16 mg mL −1 ) by desalting and gel column chromatographing [33]. Ultra-filtering of grass carp lysate with 10 kDa molecular weight MWCO ultrafiltration (UF) membrane improved IC 50 by about 3-fold (from 0.692 mg mL −1 to 0.272 mg mL −1 ) and further desalting by about 7-fold (from 0.692 mg mL −1 to 0.105 mg mL −1 ) [42]. Even so, precipitating and desalting, frequently applied to plant- and marine-based hydrolysates, is not so common for fish-hydrolysates [24,33,42].…”

“…Ultra-filtering of grass carp lysate with 10 kDa molecular weight MWCO ultrafiltration (UF) membrane improved IC 50 by about 3-fold (from 0.692 mg mL −1 to 0.272 mg mL −1 ) and further desalting by about 7-fold (from 0.692 mg mL −1 to 0.105 mg mL −1 ) [42]. Even so, precipitating and desalting, frequently applied to plant- and marine-based hydrolysates, is not so common for fish-hydrolysates [24,33,42]. Separation and purification of these molecules are well necessary for the characterization and identification of the biopeptides, in terms of amino acid sequences and molecular mass (Table 5).…”

“…Due to improved enzymatic endo-actions and specific hydrolysis of carboxyl-terminal hydrophobic amino acids, alcalase has been preferred over other common commercial and non-commercial enzymes for the extraction of ACE inhibitory peptides specifically from grass carp and other fish types [42,44,45,85]. According to Lee et al alcalase may not be suitable for the digestion of every fish type [57].…”

Effects of washing and membrane removal pretreatments on the antioxidant properties of grass carp (Ctenopharyngodon idella) protein hydrolysates produced by in vitro digestion

“…Grass carp (Ctenopharyngodon idella) is one of the 'four major cultured fish species' in China, and it has an annual production that exceeded 5.6 9 10 6 t in 2015, but it has not been developed into a high-value product. Some reports have shown that protein hydrolysates from grass carp prepared using papain, alcalase and neutrase showed antioxidant activity (Li et al, 2012;Chen et al, 2016). However, when preparing hydrolysate from fish sources, one critical problem is the existence of unstable lipid substrates and pro-oxidants (Kristinsson & Rasco, 2000).…”