Preparation and Identification of Novel Antihypertensive Peptides from the In Vitro Gastrointestinal Digestion of Marine Cobia Skin Hydrolysates

Abstract

This research focuses on cobia skin hydrolysates and their antihypertensive effects via the inhibitory activities of angiotensin I-converting enzyme (ACE). Marine fish Cobia (Rachycentron canadum) skin was hydrolysed for 5 h using Protamex and Protease N to obtain the cobia skin protein hydrolysates PX-5 and PN-5, respectively. The soluble protein and peptide contents of the PX-5 were 612 and 270 mg/g, respectively, and for the PN-5, 531 and 400 mg/g, respectively. The IC50 of PX-5 and PN-5 on ACE was 0.221 and 0.291 mg/mL, respectively. Increasing the IC50 from 0.221 to 0.044 mg/mL by simulated gastrointestinal digestion (PX-5G) reduced the ACE-inhibitory capacity of PX-5. Using gel filtration chromatography, the PX-5G was fractioned into eight fractions. The molecular weight of the fifth fraction from PX-5G was between 630 and 450 Da, and the highest inhibitory efficiency ratio on ACE was 1552.4%/mg/mL. We identified four peptide sequences: Trp-Ala-Ala, Ala-Trp-Trp, Ile-Trp-Trp, and Trp-Leu, with IC50 values for ACE of 118.50, 9.40, 0.51, and 26.80 μM, respectively. At a dose of 600 mg PX-5 powder/kg body weight, in spontaneously hypertensive rats PX-5’s antihypertensive effect significantly reduced systolic and diastolic blood pressure by 21.9 and 15.5 mm Hg, respectively, after 4 h of oral gavage.

Purification and Identification of Cholesterol Micelle Formation Inhibitory Peptides of Hydrolysate from High Hydrostatic Pressure-Assisted Protease Hydrolysis of Fermented Seabass Byproduct

“…The analysis of free amino acids was conducted in accordance with described methods, with slight modifications [ 46 , 47 ]. First, 0.5 mL of the diluted solution of sea bass protein hydrolysate (50 mg/mL) was added with 1.0 mL of Cd-ninhydrin reagent to a water bath at 84 °C for 5 min.…”

“…The measurement of soluble protein content was slightly modified from the Folin–Lowry method [ 47 , 48 , 49 ]. First, 0.1 mL of solution was extracted from the sea bass protein hydrolysate (50 mg/mL), and 0.5 mL of reagent A and 4 mL of reagent B (Bio-Rad Dc Protein Assay Kit, Bio-Rad Labortories Inc., Berkeley, CA, USA) were added to it.…”

“…For the analysis of peptide content, the determination method of Church et al [ 50 ] and Lin et al [ 47 ] was used, with slight modifications. O -phthaldialdehyde reagent and a standard calibration curve obtained from Leu-Gly reference material were used to convert the peptide content.…”

Purification and characterization of a novel angiotensin I‐converting enzyme‐inhibitory peptide derived from Alaska pollack skins

“…Chen et al (2020) also separated a novel ACE inhibitory peptide in a sequence of LSGYGP from gelatin hydrolysate protein of tilapia skin, and its IC 50 was 2.577 µmol/L. Lin et al (2019) obtained four novel ACE inhibitory peptides from cobia skin hydrolysates whose sequence was Trp-Ala-Ala, Ala-Trp-Trp, Ile-Trp-Trp, and Trp-Leu, with IC 50 values of 118.50, 9.40, 0.51, and 26.80 µM, respectively. Many studies reported the great benefits of Alaskan pollack skin hydrolysate being a food supplement due to high-quality protein and easy availability (Byun & Kim, 2001).…”

Developments for Collagen Hydrolysate in Biological, Biochemical, and Biomedical Domains: A Comprehensive Review

“…Depression and hypertension are important medical impairments that are extensively investigated with collagen hydrolysate [ 41 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 ]. Recently, a couple of efforts by the same group were presented on diminution of hypertension using novel collagen hydrolysate [ 41 , 149 ].…”