Investigation of the hypocholesterolemic mechanism of action of soy and lupin peptides

The investigations on the mechanism of action of bioactive components of functional foods and nutraceutics are not very frequent and in general not very detailed. We have recently established a cell culture lab aimed to fill this gap, starting our work from grain legumes. In fact, the seeds of grain legumes, besides being major foodstuffs in most countries, provide also some health benefits, in particular in the area of hypercholesterolemia and hypertension prevention. The main objective of the present work was to provide evidences that peptides generated by the digestion of soy and lupin proteins may be responsible of the hypocholesterolemic activity observed in vivo and to investigate the mechanism of action. In particular, a deepened study was carried out in order to characterize the hypocholesterolemic effects of pure peptides from soy proteins as well as peptide mixtures obtained by pepsin and trypsin hydrolysis of lupin proteins. The hepatic cell line HepG2 was treated with these peptides and molecular and functional investigations were performed on the LDL receptor / SREBP2 pathway. For the first time, this report provides the experimental evidence that, interfering with the HMGCoAR activity, legume peptides are able to up-regulate the LDL receptor and SREBP2 proteins via the activation of specific phosphorylation pathways and increasing the LDL-uptake at HepG2 cell line.