Antihypertensive properties of tilapia (Oreochromis spp.) frame and skin enzymatic protein hydrolysates

Abstract

Proteins from tilapia frame and skin can potentially be precursors of antihypertensive peptides according to the result of BIOPEP analyses. The aim was to generate peptides with inhibitory effects against angiotensin-converting enzyme (ACE) and renin from tilapia frame and skin protein isolates (FPI and SPI). The most active hydrolysate was then tested for blood pressure-lowering ability in spontaneously hypertensive rats (SHRs). Tilapia frame and skin protein hydrolysates (FPHs and SPHs) were respectively produced from FPI and SPI hydrolysis using pepsin, papain, or bromelain. The ACE-inhibitory activities of tilapia protein hydrolysates with varying degree of hydrolysis (DH) were evaluated. In order to enhance the activity, the hydrolysate was fractionated into four fractions (<1 kDa, 1–3 kDa, 3–5 kDa, and 5–10 kDa) and the one with the greatest ability to inhibit in vitro ACE and renin activities was subjected to oral administration (100 mg/kg body weight) to SHRs. Systolic and diastolic blood pressure (SBP and DBP), mean arterial pressure (MAP), and heart rates (HR) were subsequently measured within 24 h. The pepsin-hydrolyzed FPH (FPHPe) with the highest DH (23%) possessed the strongest ACE-inhibitory activity (IC50: 0.57 mg/mL). Its <1 kDa ultrafiltration fraction (FPHPe1) suppressed both ACE (IC50: 0.41 mg/mL) and renin activities more effectively than larger peptides. In addition, FPHPe1 significantly (p < 0.05) reduced SBP (maximum −33 mmHg), DBP (maximum −24 mmHg), MAP (maximum −28 mmHg), and HR (maximum −58 beats) in SHRs. FPHPe1 showed both in vitro and in vivo antihypertensive effects, which suggest tilapia processing coproducts may be valuable protein raw materials for producing antihypertensive peptides.

Bioactivities of enzymatic protein hydrolysates derived from Chlorella sorokiniana

“…The ability of protein hydrolysates and peptide fractions to inhibit the activity of ACE was determined using FAPGG as the synthetic substrate (Lin, Alashi, Aluko, Sun Pan, & Chang, 2017). The samples (1 mg/ml) and 0.5 m/m FAPGG were dissolved in 50 mM Tris-HCl buffer containing 0.3 NaCl at pH 7.5.…”

Dose-Related Antihypertensive Properties and the Corresponding Mechanisms of a Chicken Foot Hydrolysate in Hypertensive Rats

“…In a previous study, we observed that the administration of 5 mL/kg bw (body weight) of a chicken foot hydrolysate, Hpp11, exhibited an antihypertensive effect in spontaneously hypertensive rats (SHR), which is considered to be a model for human essential HTN [ 25 ]. Thus, considering that 100 mg/kg bw dose of other protein hydrolysates showed substantial antihypertensive effects [ 26 , 27 , 28 ], doses lower than the antihypertensive demonstrated dose of 100 mg/kg bw; 85, 55 and 25 mg/kg bw of Hpp11, were administered to SHR. Therefore, the aims of the present study were to evaluate the most effective Hpp11 dose to obtain a significant antihypertensive effect in SHR and to investigate the mechanisms underlying the Hpp11 antihypertensive effect.…”

Purification and Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides and the Antihypertensive Effect of Chlorella sorokiniana Protein Hydrolysates

“…The sequence of the peptide was identified by following the method described by Lin et al with slight modifications [ 20 ]. Samples were first prepared prior to sequencing analysis.…”

“…The five collected mixtures were then lyophilised, and their ACE-inhibitory activities and amino acid sequences were analysed. Next, the sequences of ACE-inhibitory peptides were identified through automated Edman degradation using a Procise 492 protein sequencer (Perkin-Elmer Co. Ltd., Applied Biosystem Inc., Foster City, CA, USA) [ 20 ]. Finally, the amino acid sequences of identified peptides were synthesised through solid-phase peptide synthesis.…”

“…Peptides are the most commonly studied natural compounds that inhibit ACE activity [ 8 , 9 , 10 , 11 ]. Therefore, to obtain ACE-inhibitory peptides, numerous studies have focused on the hydrolysis of food protein-based matrices such as fermented milk [ 12 , 13 , 14 ], shellfish [ 15 , 16 ], chicken [ 17 ], mushrooms [ 18 ], fish [ 19 , 20 ], and the following types of algae Undaria pinnatifida , Chlorella vulgaris , and Spirulina platensis [ 1 , 16 , 21 , 22 , 23 ]. Among these protein sources, protein from algae has received particular attention because of its potentially beneficial effects related to hypertension [ 24 , 25 , 26 ].…”