https://doi.org/10.17113/ftb.59.03.21.7087

Supplement

In vitro Antioxidant, Cytotoxic and Antidiabetic Activity of Protein Hydrolysates Prepared from Chinese Pond Turtle (Chinemys reevesii)

Md. Serajul Islam^1,2, Wang Hongxin^1,2*, Habtamu Admassu³, Amer Ali Mahdi^1,2, Ma Chaoyang² and Fu An Wei⁴

¹State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi-214122, Jiangsu province, PR China 

²National Engineering Research Center for Functional Food, Jiangnan University, 1800 Lihu Avenue, Wuxi-214122, Jiangsu province, PR China 

³Biotechnology and Bioprocessing Center of Excellence/Department of Food Process Engineering, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, Addis Ababa, Ethiopia  

⁴Guangxi Zhongtaikang Technology Industry Co., Ltd., Nanning-530029, Guangxi, PR China

Article history:

Received: 1 December 2020

Accepted: 15 July 2021

Key words:

Chinese pond turtle, molecular mass profiles, antioxidant activity, antidiabetic capacity, lipid peroxide inhibition, cytotoxic effect

Summary:

Research background. Cardiovascular diseases and diabetes are the biggest causes of death globally. Bioactive peptides derived from many food proteins using enzymatic proteolysis and food processing have a positive impact on the prevention of these diseases. The bioactivity of Chinese pond turtle muscle proteins and their enzymatic hydrolysates has not received much attention, thus this study aims to investigate their antioxidant, antidiabetic and cytotoxic activities.

Experimental approach. Chinese pond turtle muscles were hydrolysed using four proteolytic enzymes (Alcalase, Flavourzyme, trypsin and bromelain) and the degrees of hydrolysis were measured. High-performance liquid chromatography (HPLC) was conducted to explore the amino acid profiles and molecular mass distribution of the hydrolysates. The antioxidant activities were evaluated using various in vitro tests, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), hydroxyl radical scavenging activity, reducing capacity, chelating Fe²⁺ and lipid peroxide inhibition activity. Antidiabetic activity was evaluated using α-amylase inhibition and α-glucosidase inhibition assays. Besides, cytotoxic effect of hydrolysates on human colon cancer (HT-29) cells was assessed.

Results and conclusions. The amino acid composition of the hydrolysates revealed higher mass fractions of glutamic, aspartic, lysine, hydroxyproline and hydrophobic amino acids. Significantly highest inhibition of lipid peroxidation was achieved when hydrolysate obtained with Alcalase was used. Protein hydrolysate produced with Flavourzyme had the highest radical scavenging activity measured by DPPH (68.32 %), ABTS (74.12 %) and FRAP (A_{700 nm}=0.300) assays, α-glucosidase (61.80 %) inhibition and cytotoxic effect (82.26 %) on HT-29 cell line at 550 μg/mL. Hydrolysates obtained with trypsin and bromelain had significantly highest (p<0.05) hydroxyl radical scavenging (92.70 %) and Fe²⁺ metal chelating (63.29 %) activities, respectively. The highest α-amylase (76.89 %) inhibition was recorded when using hydrolysates obtained with bromelain and Flavourzyme.

Novelty and scientific contribution. Enzymatic hydrolysates of Chinese pond turtle muscle protein had high antioxidant, cytotoxic and antidiabetic activities. The findings of this study indicated that the bioactive hydrolysates or peptides from Chinese pond turtle muscle protein can be potential ingredients in pharmaceuticals and functional food formulations.