6932
K. L. Howell et al. / Bioorg. Med. Chem. Lett. 20 (2010) 6929–6932
prepared with improvements in binding affinity to NPC1L1
Compounds dosed 30 min prior to cholesterol
observed for 4-substituted analogs including those containing pyr-
azole groups. Non-b-lactam compound 24, which contains both the
4-t-butyl benzamide and a 4-pyrazolylpiperidine, demonstrated
dose-dependent cholesterol-lowering efficacy in mice. Significant
improvements in binding affinity and in vivo efficacy will be
required to determine if non-b-lactam CAIs will be viable leads
for this class of LDL-reducing therapy.
5hr cholesterol
1.5hr cholesterol
absorption
absorption
90
+/- 0.4
75
67
+/- 3
100
50
62
+/- 2
48
+/- 10
+/- 4
35
+/- 8
Acknowledgment
The authors thank Eric Streckfuss for his help with the mass-
directed preparatory HPLC instrument which enabled rapid purifi-
cation of compounds.
0
mg/kg
1
1
10 30 100
24 24 24
1
1
100
24
compound
References and notes
Figure 2. %Inhibition (mean SE) of 3H-cholesterol absorption in C57BL/6 mice
(values are means of six datapoints).
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SAR studies showed carboxylic acids had low binding affinities
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1523 lM IC50 in human, respectively).
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The compounds were tested for their ability to inhibit choles-
terol absorption in mice. To that end, compounds were pre-dosed
orally in C57BL/6 male mice in a 0.2-mL 0.25% methocel suspen-
sion. Thirty minutes later, the mice were orally dosed with a
0.2 mL mixture of tritium radiolabeled cholesterol in IntraLipid.
After 1.5 h and 5 h, the mice were euthanized and weighed. The
blood was collected by cardiac puncture, and the plasma 3H-cho-
lesterol was measured. The liver was collected, weighed, and
saponified, and the liver 3H-cholesterol was measured. Six data
points were taken per dosage and averaged, and the standard
deviation and standard error were determined.
Several of the analogs shown in Tables 1 and 2 were screened in
the MICA at 10 or 100 mg/kg, and the results are shown in
parentheses.
The most promising efficacy was observed for pyrazole analog
24. A dose-dependent effect is observed for compound 24, with
the greatest efficacy (62% inhibition) at the 100-mg/kg dose at
the 1.5-hour time point (Fig. 2). At the 5-hour time point, the level
of inhibition of cholesterol absorption in plasma increased to 67%.
Spiroimidazolidinone 24 also reduced cholesterol in the liver (data
not shown). These data demonstrate the potential for non-b-lac-
tam compounds to act as cholesterol-absorption inhibitors in mice.
We have identified spiroimidazolidinones as a novel lead class
of NPC1L1 inhibitors and explored the SAR of binding affinity of
this novel class of CAIs. A series of substituted piperidines were
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Larsen, S. D.; Van Huis, C.; Sorenson, R.; Barton, T.; Winters, T.; Auerbach, B.;
Wu, C.; Wolfram, T. J.; Cai, H.; Welch, K.; Esmaiel, N.; Davis, J.; Bousley, R.;
Olsen, K.; Mueller, S. B.; Mertz, T. Bioorg. Med. Chem. Lett. 2008, 18, 546.
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Bull, H. G.; Lisnock, J. M.; Dean, D. C. Bioorg. Med. Chem. Lett. 2009, 19,
5033.