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 perform a positive impact on the prevention of these diseases. The bioactivity of grass turtle muscle proteins and their enzymatic hydrolysates has not received much attention, thus this study aims to investigate the antioxidant, antidiabetic, and cytotoxic activities of the enzymatic hydrolysates of grass turtle muscle protein.
Experimental approach. Grass turtle muscle(s) was hydrolysed using four proteolytic enzymes (Alcalase (AH), Flavourzyme (FH), Trypsin (TH), and Bromelain (BH)). The degree of hydrolysis was measured. High performance liquid chromatography (HPLC) was conducted to explore their 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 (•OH) radical scavenging activities, reducing capacity, chelating (Fe2+), and lipid peroxide inhibition activity. Antidiabetic activity was evaluated against α-amylase inhibition and α-Glucosidase inhibition assay. 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 that higher contents of glutamic, aspartic, lysine, hydroxyproline, and hydrophobic amino acids. AH showed significantly the highest inhibition of lipid peroxidation. FH showed the highest lipid peroxidation, strongest radical scavenging activity of DPPH (68.32 %), ABTS (74.12 %), FRAP (0.30 unit), α-glucosidase (61.80 %) and cytotoxic effect on cancer cells (82.26 %) at 550 µg/mL for HT-29 cell line. TH and BH were showed significant (p<0.05) hydroxyl radical activity (92.70 %) and Fe2+ metal chelating (63.29 %), respectively. The highest α-amylase (76.89 %) inhibition was recorded by BH and FH.
Novelty and scientific contribution. Enzymatic grass turtle muscle(s) proteins hydrolysates achieved great antioxidant, cytotoxic, and antidiabetic activity. The findings of this study indicated that the bioactive hydrolysates /peptides from grass turtle muscle(s) protein could be potential candidate as ingredients in pharmaceuticals and functional food formulations.
In vitro Antioxidant, Cytotoxic and Antidiabetic Activity of Protein Hydrolysates Prepared from Grass Turtle (Chinemys reevesii)
