Protein Fraction and Derived Peptides from Amaranthus hypochondriacus: A Preliminary In Vitro Study of Cytotoxic Activity in Cancer Cell Lines

Amaranth proteins have been associated with various health benefits, including anticancer activity. This study aimed to evaluate the cytotoxic effect of proteins and peptides derived from Amaranthus hypochondriacus. A crude extract (CE) and protein fraction (PF) were obtained; peptides were produced by enzymatic hydrolysis, yielding one sample >30 kDa (P > 30 kDa) and another < 30 kDa (P < 30 kDa). Protein, phenolic, and antinutritional compounds contents were determined, along with antioxidant capacity and cytotoxic activity against MDA-MB-231 and SiHa cells. CE exhibited the highest protein content of 182.6 mg/g, total phenols 129.40 mg GAE/g, and antioxidant capacity by both methods, 104.50 µM TEAC/g for ABTS•+ and 75.62 µM TEAC/g for DPPH•. PF showed the greatest concentration of saponins and lectins, 80 HU/mg and 60.30 HA/mg, respectively. PF displayed the strongest cytotoxic effect at 72 h in both cell lines, with IC50 of 44.98 µg/mL for MDA-MB-231 cells and 69.24 µg/mL for SiHa cell line. Transmission electron microscopy (TEM) revealed severe structural damage induced by PF in both cell lines. In conclusion, PF from Amaranthus hypochondriacus seeds showed the greatest in vitro cytotoxic effect against both cancer cell lines, principally in MDA-MB-231 cells.