PyrGF and GSTLN peptides enhance pravastatin's inhibition of 3-hydroxy-3-methyl-glutaryl coenzyme

Two newly designed peptides, Pyr-GF and GSTLN, enhance pravastatin inhibition of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGCoAR). In silico experiments have demonstrated the interaction of these peptides with the catalytic and NADPH sites of HMGCoAR. In vitro, the Pyr-GF (IC50 = 117.4 μM) and GSTLN (IC50 = 278.1 μM) peptides exhibit dose-dependent inhibition on the HMGCoAR activity, and the effects are more significant than those observed for original peptides obtained from cowpea and adzuki beans. Compared to pravastatin alone, the Pyr-GF/pravastatin combination produced a small decrease (8%) in HMGCoAR activity, whereas the GSTLN/pravastatin combination produced a significant decrease of 41% on HMGCoAR activity. The association between Pyr-GF/GSTLN peptides decreased the IC50 to 71.8 μM. These results suggest their interaction with different sites; Pyr-GF and pravastatin mainly act on the catalytic site and GSTLN on the NADPH site. Hence, the Pyr-GF and GSTLN peptides and their combination exhibit a cholesterol-lowering effect and act as adjuvants upon association with pravastatin.