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A novel series of substituted N-[3-(1,1,2,2-tetrafluoroethoxy)benzyl]-N-(3-phenoxyphenyl)-trifluoro-3-amino-2-propanols is described which potently and reversibly inhibit cholesteryl ester transfer protein (CETP). Starting from the initial lead 1, various substituents were introduced into the 3-phenoxyaniline group to optimize the relative activity for inhibition of the CETP-mediated transfer of [3H]-cholesteryl ester from HDL donor particles to LDL acceptor particles either in buffer or in human serum. The better inhibitors in the buffer assay clustered among compounds in which the phenoxy group was substituted at the 3, 4, or 5 positions. In general, small lipophilic alkyl, haloalkyl, haloalkoxy, and halogen moieties increased potency relative to 1, while analogues containing electron-donating or hydrogen bond accepting groups exhibited lower potency. Compounds with polar or strong electron-withdrawing groups also displayed lower potency. Replacement of the phenoxy ring in 1 with either simple aliphatic or cycloalkyl ethers as well as basic heteroaryloxy groups led to reduced potency. From the better compounds, a representative series 4a-i was prepared as the chirally pure R(+) enantiomers, and from these, the 4-chloro-3-ethylphenoxy analogue was identified as a potent inhibitor of CETP activity in buffer (4a, IC50 0.77 nM, 59 nM in human serum). The simple R(+) enantiomer 4a represents the most potent acyclic CETP inhibitor reported. The chiral synthesis and biochemical characterization of 4a are reported along with its preliminary pharmacological assessment in animals.

A novel series of substituted N-benzyl-N-phenyl-trifluoro-3-amino-2-propanols are described that reversibly inhibit cholesteryl ester transfer protein (CETP). Starting with screening lead 22, various structural features were explored with respect to inhibition of the CETP-mediated transfer of [(3)H]cholesterol from high-density cholesterol donor particles to low-density cholesterol acceptor particles. The free hydroxyl group of the propanol was required for high potency, since acylation or alkylation reduced activity. High inhibitory potency was also associated with 3-ether moieties in the aniline ring, and the highest potencies were exhibited by 3-phenoxyaniline analogues. Activity was substantially reduced by oxidation or substitution in the methylene of the benzylic group, implying that the benzyl ring orientation was important for activity. In the benzylic group, substitution at the 3-position was preferred over either the 2- or the 4-positions. Highest potencies were observed with inhibitors in which the 3-benzylic substituent had the potential to adopt an out of plane orientation with respect to the phenyl ring. The best 3-benzylic substituents were OCF(2)CF(2)H (42, IC(50) 0.14 microM in buffer, 5.6 microM in human serum), cyclopentyl (39), 3-iso-propoxy (27), SCF(3) (67), and C(CF(3))(2)OH (36). Separation of 42 into its enantiomers unexpectedly showed that the minor R(+) enantiomer 1a was 40-fold more potent (IC(50) 0.02 microM in buffer, 0.6 microM in human serum) than the major S(-) enantiomer 1b, demonstrating that the R-chirality at the propanol 2-position is key to high potency in this series. The R(+) enantiomer 1a represents the first reported acyclic CETP inhibitor with submicromolar potency in plasma. A chiral synthesis of 1a is reported.

High-throughput screening (HTS) of compound libraries is used to discover novel leads for drug development. When a structure is available for the target, computer-based screening using molecular docking may also be considered. The two techniques have rarely been used together on the same target. The opportunity to do so presented itself in a project to discover novel inhibitors for the enzyme protein tyrosine phosphatase-1B (PTP1B), a tyrosine phosphatase that has been implicated as a key target for type II diabetes. A corporate library of approximately 400 000 compounds was screened using high-throughput experimental techniques for compounds that inhibited PTP1B. Concurrently, molecular docking was used to screen approximately 235 000 commercially available compounds against the X-ray crystallographic structure of PTP1B, and 365 high-scoring molecules were tested as inhibitors of the enzyme. Of approximately 400 000 molecules tested in the high-throughput experimental assay, 85 (0.021%) inhibited the enzyme with IC50 values less than 100 microM; the most active had an IC50 value of 4.2 microM. Of the 365 molecules suggested by molecular docking, 127 (34.8%) inhibited PTP1B with IC50 values less than 100 microM; the most active of these had an IC50 of 1.7 microM. Structure-based docking therefore enriched the hit rate by 1700-fold over random screening. The hits from both the high-throughput and docking screens were dissimilar from phosphotyrosine, the canonical substrate group for PTP1B; the two hit lists were also very different from each other. Surprisingly, the docking hits were judged to be more druglike than the HTS hits. The diversity of both hit lists and their dissimilarity from each other suggest that docking and HTS may be complementary techniques for lead discovery.

A series of novel N,N-disubstituted trifluoro-3-amino-2-propanols has been prepared as potent inhibitors of cholesteryl ester transfer protein (CETP). Modifying the aromatic 3-tetrafluoroethoxy group in the lead molecule 1a with various heteroaryl moieties produced new 2-furyl analogues 2a,b with submicromolar potency in vitro.

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.