Pure peptides from amaranth (Amaranthus hypochondriacus) proteins inhibit LOX-1 receptor and cellular markers associated with atherosclerosis development in vitro

The objectives were to evaluate and to compare the effect of pure peptides from amaranth proteins on markers that promote atherosclerosis, in vitro. Amaranth pure peptides with potential anti-atherosclerotic effect, HGSEPFGPR, RPRYPWRYT and RDGPFPWPWYSH, were studied using lipopolysaccharide-induced THP-1 human macrophage-like cells. Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) expression was reduced by peptides HGSEPFGPR (83%), RDGPFPWPWYSH (49%) and RPRYPWRYT (63%); while intracellular adhesion molecule-1 (ICAM-1) was reduced by peptides RDGPFPWPWYSH (27%) and RPRYPWRYT (39%); and matrix metalloproteinase-9 (MMP-9) expression was reduced by 52% (HGSEPFGPR), 41% (RDGPFPWPWYSH) and 29% (RPRYPWRYT). Using confocal microscopy, peptide HGSEPFGPR reduced LOX-1, ICAM-1 and MMP-9 expression by 74%, 59% and 80%, respectively. RPRYPWRYT reduced LOX-1, ICAM-1 and MMP-9 expression by 48%, 49% and 71%, respectively. RPRYPWRYT reduced MCP-1 and TGF-β cellular protein expression (74% and 78%, respectively); 89% (IL-6 and IL-1α); 83% (IFN-γ); 87% and 58% (TNF-α and TNF-β). HGSEPFGPR showed significant reduction of 27%, 31%, 41%, 57%, and 61% for GRO-α, MCP-1, IL-6, IL-1α, and RANTES, respectively. HGSEPFGPR showed better interactions with LOX-1 crystal structure than RPRYPWRYT. Amaranth pure peptides reduced the expression of proteins associated with LOX-1 signaling pathway, in vitro.