Growth inhibition and apoptosis induction in hepatocellular carcinoma cells by partially purified nutraceutical proteins from quinoa bran

Chenopodium quinoa, a pseudocereal, is gaining global attention for its unique nutritional properties. Quinoa
bran, a natural milling byproduct, is rich in vital nutrients and nutraceutical compounds that exhibit various
biological activities. The current study investigated the antiproliferative effect of nutraceutical proteins extracted
from quinoa bran on hepatocellular carcinoma (HCC) cells. Bioactive proteins were purified using various
chromatographic methods, resulting in two partially purified fractions (P2 and P3), that demonstrated dose- and
time-dependent growth inhibition of Hep3B and HepG2 cells. The IC50 values for P2 and P3 against Hep3B cells
were 48.39 μg/mL and 24.30 μg/mL, respectively, and for HepG2 cells, were 26.08 μg/mL and 61.84 μg/mL. The
P2 and P3-induced apoptosis was evidenced by the activation of Caspase-3/7 and DNA fragmentation. Cell cycle
analysis revealed an increased population of Sub G0 and S phases. Annexin-V-FITC staining showed a higher
apoptotic population with increasing protein concentration. Enhanced expression of Bax and reduced levels of
the antiapoptotic protein Bcl-2, followed by the cleavage of pro-caspase-3 and PARP suggested the possible
involvement of the intrinsic apoptotic pathway. In-vivo studies on Swiss albino mice bearing EAC tumors
demonstrated a significant reduction in tumor size compared to the control group. Peptide mass fingerprinting by
LC-MS/MS identified probable bioactive proteins, including antiviral MAP-like proteins, trypsin inhibitor DE3-
like, and ribosome-inactivating protein-like. Thus, the current study revealed that quinoa bran proteins have a
potential antitumor effect and warrant a detailed study for their application in functional foods.