Antihypertensive Properties of Tilapia (Oreochromis spp.) Frame and Skin Enzymatic Protein Hydrolysates

• Main Authors: Lin, Hsin-Chieh, 林欣潔
• Other Authors: Chang, Yu-Wei
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/d77f69

碩士 === 國立臺灣海洋大學 === 食品科學系 === 105 === Proteins from tilapia processing by-products can be potential precursors of bioactive peptides with antihypertensive, antioxidative, antithrombotic, or anti-amnestic activities according to the sequence results of in silico prediction using BIOPEP database. In this study, tilapia frame and skin protein isolates (FPI and SPI) were individually hydrolyzed for 4 hrs using either 1% (enzyme/substrate, w/w) pepsin, papain or bromelain. The pepsin-hydrolyzed frame protein hydrolysates (FPHPe) with a degree of hydrolysis (DH) of 23% found 80% inhibiton against angiotensin I-converting enzyme (ACE) activity while bromelain-hydrolyzed skin protein hydrolysates (SPHBr) with a lower DH (10%) had 40% at a concentration of 1 mg/mL. In vitro ACE-inhibitory activity of frame and skin protein hydrolysates (FPHs and SPHs) was much greater than the anti-amnestic property evaluated by prolyl endopeptidase (PEP) and acetylcholinesterase (AChE) inhibition (<23%). The <1 kDa ultrafiltration fraction from FPHPe (FPHPe1) composed of peptides mostly ranging from 150–400 kDa, exhibiting stronger inhibitory activities against ACE (IC50, 0.41 mg/mL) and renin than the peptides with higher molecular weights. Besides, FPHPe1 significantly (p <0.05) reduced systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR) after oral administration (100 mg/kg body weight) to spontaneously hypertensive rats (SHRs). The maximal decreases of SBP, DBP, MAP, and HR within 24 h were 33 mmHg, 24 mmHg, 28 mmHg, and 58 bpm, respectively. In conclusion, FPHPe1 showed both in vitro ACE- and renin-inhibitory activities and in vivo antihypertensive effects, which suggests tilapia processing by-products may be a valuable protein raw material for producing antihypertensive peptides.