Tropifexor (LJN452) is a novel and highly potent agonist of FXR with an EC50 of 0.2 nM.

FXR:EC50: 0.2 nM

在原代细胞中，Tropifexor以浓度依赖的方式显著诱导BSEP和SHP基因的表达。当浓度低至1 nM时，观察到BSEP的诱导程度超过载体(DMSO)对照；而SHP的强烈诱导（比载体高出15倍）在10 nM时观察到，1 nM时SHP的诱导较为适度（比载体高出3倍）。

给大鼠施用Tropifexor后，可明显看到血浆中FGF15蛋白水平以剂量依赖性方式增加，7小时后达到最大水平。连续14天使用Tropifexor可显著降低血清甘油三酯，以0.3 mg/kg剂量达到最大反应，甘油三酯水平下降至对照组的79%。Tropifexor在最低剂量0.1 mg/kg时即可在回肠中高度诱导SHP和FGF15的表达。在肝脏中，0.01 mg/kg的Tropifexor即可显著诱导SHP的表达，0.3 mg/kg时达到基因诱导的最高水平。在连续使用Tropifexor 14天后，最低剂量（0.003 mg/kg）即可观察到CYP8B1 mRNA的表达，而在超过0.03 mg/kg剂量时，CYP8B1基因表达完全被抑制。

Primary rat hepatocytes are plated in 24 well plates and incubated with a 5 point dose response of Tropifexor (compound 1) for 24 hours. RNA is harvested from the cells using the RNeasy 96 kit. Quantitative PCR is performed. The fold change of the transcript over no stimulation is calculated using the ΔΔCt method, with DMSO (vehicle control) being no stimulation.

Adult male wild-type Sprague-Dawley rats are used in this study. All animals are fasted for 3 hours before oral dosing with Tropifexor (compound 1) or with vehicle. Tropifexor is administered orally using a range of four doses (0.03, 0.1, 0.3, and 1.0 mg/kg) and compare directly to the vehicle control group (vehicle: 0.5% methylcellulose, 0.5% Tween 80, 99% water, suspension). Animals are sacrificed seven hours after dosing using CO2, liver, ileum and whole blood (in heparinized tubes) samples are collected for analysis.