Hempseed Peptides Exert Hypocholesterolemic Effects with a Statin-Like Mechanism

This study had the objective of preparing a hempseed protein hydrolysate and investigating its hypocholesterolemic properties. The hydrolysate was prepared treating a total protein extract with pepsin. Nano HPLC-ESI-MS/MS analysis permitted identifying in total 90 peptides belonging to 33 proteins. In the range 0.1-1.0 mg/mL, it inhibited the catalytic activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCoAR) in a dose-dependent manner. HepG2 cells were treated with 0.25, 0.5, and 1.0 mg/mL of the hydrolysate. Immunoblotting detection showed increments in the protein levels of regulatory element binding proteins 2 (SREBP2), low-density lipoprotein receptor (LDLR), and HMGCoAR. However, the parallel activation of the phospho-5'-adenosine monophosphate-activated protein kinase (AMPK) pathway, produced an inactivation of HMGCoAR by phosphorylation. The functional ability of HepG2 cells to uptake extracellular LDL was raised by 50.5 ± 2.7%, 221.5 ± 1.6%, and 109 ± 3.5%, respectively, versus the control at 0.25, 0.5, and 1.0 mg/mL concentrations. Finally, also a raise of the protein level of proprotein convertase subtilisin/kexintype 9 was observed. All of these data suggest that the mechanism of action has some similarity with that of statins.