β-conglycinins among sources of bioactives in hydrolysates of different soybean varieties that inhibit leukemia cells in vitro

Soybean is a complex matrix containing several potentially bioactive components. The objective was to develop a statistical model to predict the in vitro anticancer potential of soybean varieties based on the correlation between protein composition and bioactive components after simulated gastrointestinal enzyme digestion with their effect on leukemia mouse cells. The IC₅₀ values of the hydrolysates of soy genotypes (NB1-NB7) on L1210 leukemia cells ranged from 3.5 to 6.2 mg/mL. Depending on genotype, each gram of soy hydrolysates contained 2.7-6.6 μmol of total daidzein, 3.0-4.7 μmol of total genistein, 0.5-1.3 μmol of glycitein, 2.1-2.8 μmol of total saponins, 0.1-0.2 μmol of lunasin, and 0.1-0.6 μmol of Bowman-Birk inhibitor (BBI). The IC₅₀ values calculated from a partial least-squares (PLS) analysis model correlated well with experimental data (R² = 0.99). Isoflavones and β-conglycinin positively contributed to the cytotoxicity of soy on L1210 leukemia cells. Lunasin and BBI were potent L1210 cell inhibitors (IC₅₀ = 13.9 and 22.5 μM, respectively), but made modest contributions to the activity of defatted soy flour hydrolysates due to their relatively low concentrations. In conclusion, the data demonstrated that β-conglycinins are among the major protein components that inhibit leukemia cell growth in vitro. Furthermore, it was feasible to differentiate soybean varieties on the basis of the biological effect of their components using a statistical model and a cell-based assay.