DL5050, a Selective Agonist for the Human Constitutive Androstane Receptor.

The constitutive androstane receptor (CAR) is a xenobiotic sensor governing the transcription of genes involved in drug disposition, energy homeostasis, and cell proliferation. However, currently available human CAR (hCAR) agonists are nonselective, which commonly activate hCAR along with other nuclear receptors, especially the closely related human pregnane X receptor (hPXR). Using a well-known hCAR agonist CITCO as a template, we report our efforts in the discovery of a potent and highly selective hCAR agonist. Two of the new compounds of the series, 18 and 19 (DL5050), demonstrated excellent potency and selectivity for hCAR over hPXR. DL5050 preferentially induced the expression of CYP2B6 (target of hCAR) over CYP3A4 (target of hPXR) on both the mRNA and protein levels. The selective hCAR agonist DL5050 represents a valuable tool molecule to further define the biological functions of hCAR, and may also be used as a new lead in the discovery of hCAR agonists for various therapeutic applications.