Stereospecific Inhibition of CETP by ChiralN,N-Disubstituted Trifluoro-3-amino-2-propanols

Abstract

Chiral N,N-disubstituted trifluoro-3-amino-2-propanols represent a recently discovered class of compounds that inhibit the neutral lipid transfer activity of cholesteryl ester transfer protein (CETP). These compounds all contain a single chiral center that is essential for inhibitory activity. (R,S)SC-744, which is composed of a mixture of the two enantiomers, inhibits CETP-mediated transfer of [(3)H]cholesteryl ester ([(3)H]CE) from HDL donor particles to LDL acceptor particles with an IC(50) = 200 nM when assayed using a reconstituted system in buffer and with an IC(50) = 6 microM when assayed in plasma. Upon isolation of the enantiomers, it was found that the (R,+) enantiomer, SC-795, was about 10-fold more potent than the mixture, and that the (S,-) enantiomer, SC-794, did not have significant inhibitory activity (IC(50) > 0.8 microM). All of the activity of the (S,-)SC-794 enantiomer could be accounted for by contamination of this sample with a residual 2% of the highly potent (R,+) enantiomer, SC-795. The IC(50) of (R,+)SC-795, 20 nM, approached the concentration of CETP (8 nM) in the buffer assay. These chiral N,N-disubstituted trifluoro-3-amino-2-propanols were found to associate with both LDL and HDL, but did not disrupt overall lipoprotein structure. They did not affect the on or off rates of CETP binding to HDL disk particles. Inhibition was highly specific since the activities of phospholipid transfer protein and lecithin cholesterol acyl transferase were not affected. Competition experiments showed that the more potent enantiomer (R)SC-795 prevented cholesteryl ester binding to CETP, and direct binding experiments demonstrated that this inhibitor bound to CETP with high affinity and specificity. It is estimated, based on the relative concentrations of inhibitor and lipid in the transfer assay, that (R)SC-795 binds approximately 5000-fold more efficiently to CETP than the natural ligand, cholesteryl ester. We conclude that these chiral N,N-disubstituted trifluoro-3-amino-2-propanol compounds do not affect lipoprotein structure or CETP-lipoprotein recognition, but inhibit lipid transfer by binding to CETP reversibly and stereospecifically at a site that competes with neutral lipid binding.

Description of the torcetrapib series of cholesteryl ester transfer protein inhibitors, including mechanism of action

“…Why a previous study had found no effect of SC-795 on CETP binding to HDL is not known (31). However, in the latter case, synthetic HDL was used for SPR experiments, whereas our experiments used native HDL.…”

“…A second inhibitor series with an apparently similar mode of action A number of N,N-disubstituted trifluoro-3-amino-2-propanols, represented by SC-795, have previously been reported to bind specifically to CETP and block CE binding (31). Studies of CETP binding to immobilized synthetic HDL disks by SPR detected no difference in either the presence or the absence of SC-795.…”

New CETP inhibitor K-312 reduces PCSK9 expression: a potential effect on LDL cholesterol metabolism

“…In vitro CETP inhibitory activity of compounds was measured using previously reported methods (8). CETP inhibitors were incubated with human plasma for 4 h at 37°C prior to the CETP activity being measured.…”

Efficacy and Safety of a Novel Cholesteryl Ester Transfer Protein Inhibitor, JTT-705, in Humans

“…Various successful strategies already have been developed to inhibit plasma CETP activity. [7][8][9] CETP antibodies can inhibit CETP activity and increase HDL-C in hamsters. 10 Also, antisense oligodeoxynucleotides against CETP mRNA, as well as a vaccine that elicits antibodies that block CETP function, lead to significant increases in HDL-C, accompanied by a marked reduction of aortic cholesterol content in rabbits.…”