Peptides from soybean β-conglycinin modulate lipid homeostasis, oxidation and inflammatory state in in vitro systems

Lipid homeostasis, oxidation and inflammatory state play an important role in the development of several diseases such as atherosclerosis and cancer. The object was to evaluate the effects of five peptides (A=SEEEEEDQ, B=QKEEEKHEWQ, C=RKQEEDEDEEQQRE, D=EITPEKNPQLR, E=KNPQLR) from soybean β-conglycinin on lipid homeostasis, NO production, iNOS and COX-2 expression, respectively in HepG2 cells, adipocyte (3T3-L1) and macrophage (RAW 264.7) cell lines. Lipid homeostasis markers: peptides C and E, both at 1 μM, showed an increased expression (mRNAs) of LDL-R (+2.3 and +1.9 fold, respectively), SREBP2 (+1.8 and +3.3 fold, respectively), and a decrease in HMGCoA reductase (-0.71 and -0.31%, respectively). Peptides A, B and D were ineffective. Inflammatory mediators: peptides A, B, and E, tested at 25 μM, reduced the expression of iNOS (-71, -75 and -44, respectively) and COX-2 (-54, -34 and -79, respectively); peptides C, D showed lower inhibitory capacity. These in vitro data suggest the potential use of soy peptides as nutraceuticals in lipid lowering therapy and in the improvement of the inflammatory state.