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.

Keywords:

• Cuora trifasciata
• hydrolysis
• peptides
• antitumor
• nanoencapsulation

Disclosure statement

The authors report that they have no conflicts of interest. This study was supported by Ocean and Fisheries Development Project (A201401C08) from Administration of Ocean and Fisheries of Guangdong Province, and National High-Tech Research and Development Project (863 Programme) (2014AA022004).