Anticancer properties of peptides and protein hydrolysates derived from Asian water monitor (Varanus salvator) serum

This study investigated the anticancer efficacy of <3 kDa fractions derived from native peptides and protein hydrolysate of Varanus saltator serum. The inhibitory effects of these fractions were evaluated against a panel of cancer cell lines (A375, CaCO2, CAL27, NCI-H460, HeLa, HCT8, HT29, HepG2, KATO III, MCF-7, MDA-MB-231, Raw264.7, SKOV-3, SW620, T47D, and U937) and normal cell lines (HaCaT, MRC5, and Vero). Native peptides demonstrated higher anticancer activity compared to protein hydrolysates, inhibiting 16 cell lines and exhibiting high efficacy (≥70% inhibition) against CaCO2, CAL27, HaCaT, HT29, HepG2, MCF-7, MRC5, and U937. These native peptides were further fractionated by stepwise reverse-phase column chromatography. The hydrophilic (C18 unbound) peptide fraction exhibited greater anticancer activity than the hydrophobic (C18 bound) fraction. In addition, by LC-MS analysis, the peptide sequences were screening in silico. The predictions showed that 159 of the 432 Varanus peptides had the potential to be anticancer peptides (ACPs), of which the top twenty had a probability of more than 75%. The anticancer mechanism of peptides may be explained by the mechanism of cell entry or action. Further peptide synthesis and modification should be the next step to enhance the anticancer efficacy of these peptides with less toxicity to Vero cells. This finding sets the way for the development of new anticancer drugs originating from Varanus salvator serum peptides.