Separation and nanoencapsulation of antitumor peptides from Chinese three-striped box turtle (Cuora trifasciata)

Abstract

Chinese three-striped box turtle (Cuora trifasciata), as a freshwater turtle, is used as a tonic food. The purpose of this study was to isolate peptides with cancer growth inhibition activity from trypsin-digested hydrolysates of turtle proteins. The results demonstrated that two fractions T1 and T2 exhibited good inhibition on HepG-2 and MCF-7 cancer cells, with an inhibition of 70.65-89.1%, at 500 μg/mL. Subsequently, three peptides were identified from T1 and T2, including RGVKGPR (T1-1), KLGPKGPR (T1-2), and SSPGPPVH (T2-1). By database search, T2-1 was a completely new peptide; its inhibition activity on MCF-7 cancer cells was the best, up to 70.02% at 500 μg/mL. Then, T1 and T2-1 were nanoencapsulated by chitosan. After nanoencapsulation, the inhibition percentages were 50.23% for the nanoencapsulated T1 on HepG-2 and 46.82% for the encapsulated T2-1 on MCF-7. The release experiment indicated that the encapsulated peptides could be slowly released in simulated gastrointestinal juice.

Anticancer potential of bioactive peptides from animal sources

“…He et al (129) have reported antitumor peptides derived from the enzymatic hydrolysates of the Chinese three-striped box turtle (Cuora trifasciata). Two fractions, T1 and T2, inhibit HepG2 and MCF-7 cancer cells, and three peptides have been identified in these fractions: RgVKgPR (T1-1), KLgPKgPR (T1-2), and SSPGPPvH (T2-1).…”

Soft-Shelled Turtle Peptide Supplementation Modifies Energy Metabolism and Oxidative Stress, Enhances Exercise Endurance, and Decreases Physical Fatigue in Mice

“…Recently, bioactive peptides derived from food proteins have been discovered with potent physiological activities such as antioxidant [ 11 ], anticancer, antibacterial, antifungal, and antitumor properties, as well as ion channel blockers, which opened a new standpoint for developing fatigue-relieving products [ 12 ]. Researchers have successfully isolated peptides possessing antifatigue potentials from aquatic organisms, e.g., sea cucumber, cod, hairtail and turtle [ 13 , 14 , 15 , 16 ]. The soft-shelled turtle ( Pelodiscus sinensis ) is a traditional Chinese nourishing food.…”

Exploring the global animal biodiversity in the search for new drugs - Reptiles

“…The powder did not affect ascites tumors in the mice, suggesting that it did not directly kill tumor cells and may act by activating the immune system [250]. Other studies on the antitumor activity of testudines' parts reported cytotoxic effects of the extract from the shell of the Greek tortoise Testudo graeca (Testudinidae) and of peptides isolated from enzymatic hydrolysates of proteins from the Chinese three-striped box turtle C. trifasciata to various animal and human carcinoma cell lines [251,252]. Furthermore, peptides from the Chinese softshell turtle P. sinensis altered microRNA expression in the AGS human gastric adenocarcinoma cell line involving, among others, upregulation of several tumor suppressor miRNAs [253].…”