Peptides derived from high oleic acid soybean meals inhibit colon, liver and lung cancer cell growth

Soybean meal, a co-product after oil extraction from seeds, is rich in protein. Our objective was to utilize this co-product, obtain gastrointestinal (GI) resistant peptides from the isolated protein, and test for bioactivity against colon, liver and lung cancer cell lines. N98-4445A, S03-543CR high oleic acid soybean lines, and R95-1705 high protein soybean line were used for this study. Protein isolates were prepared at alkaline pH and hydrolyzed using alcalase enzyme to generate peptide hydrolysates. After determining gastrointestinal resistance of the peptide hydrolysates they were fractionated into definite molecular sizes of <5 kDa, 5-10 kDa, and 10-50 kDa and tested against human colon (HCT-116, Caco-2), liver (HepG-2) and lung (NCL-H1299) cancer cell lines. MTS, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium, cytotoxicity assay was performed to test in vitro cancer cell viability upon treatment with peptide fractions. The peptide fractions from N98-4445A and S03-543CR lines showed cell growth inhibition of 73% of colon cancer (HCT-116), 70% of liver cancer cells and 68% of lung cancer cells. Dose response showed that the peptides had significant inhibitory effect at higher concentrations (1000 mu g/mL to 600 mu g/mL) and gradually decreased with decreased dosage (500 mu g/mL to 100 mu g/mL). Reverse phase HPLC identified three single peptides from the 10-50 kDa fractions of N98-4445A soy line that have potential for enhanced activity. Soybean peptide fractions can thus be a source of bioactivity against colon, liver and lung cancer cell proliferation. (c) 2012 Elsevier Ltd. All rights reserved.