SR12813 (GW 485801) is a pregnane X receptor (PXR) agonist.

HMG-CoA reductase:850 nM

SR12813 is a very potent and efficacious activator of both the human and rabbit PXR, with EC50 values of approximately 200 nM and 700 nM, respectively. By contrast, SR12813 is only a very weak activator of the rat and mouse PXR[1]. SR-12813 inhibits incorporation of tritiated water into cholesterol with an IC50 of 1.2 μM but has no effect on fatty acid synthesis. SR-12813 reduces cellular 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity with an IC50 of 0.85 μM. The inhibition of HMG-CoA reductase activity is rapid with a T1/2 of 10 min[2].

The bisphosphonate ester SR12813 lowers cholesterol levels in a range of species including rats, dogs and primates[1].

Briefly, compounds are added to the cells in Me2SO (final concentration, 0.1%). After the experiment cells are lysed by the addition of 0.1 mL of 0.25% Brij 96, 0.1 M sucrose, 0.1 M KF, 50 mM KCl, 40 mM potassium dihydrophosphate, 30 mM EDTA, 5 mM dithiothreitol, pH 7.4 at room temperature. In some experiments KF is omitted to measure 'total' HMG-CoA reductase activity. HMG-CoA reductase activity in the cell lysate is further determined.

Hep G2 cells are incubated for 21 h with either 1 μM lovastatin or 3 μM SR-12813 in 5% LPDS medium. mRNA is isolated and analyzed by Northern blotting.(Only for Reference)