Cell experiment:

HepG2-derived cells stably expressing the CYP3A4 reporter gene (3-1-10 cells) are used in this experiment. The cells are treated with 0.3 to 30 μM Pyributicarb for 48 h. Then reporter activities are determined[1].

Animal experiment:

Male ICR mice (5 weeks old) are used and fed standard rodent chow. After 18-h fasting, mice are injected i.v. with adenovirus [4.0 ×109 50% titer culture infectious dose (TCID50)/mouse]. Three days after the infection, vehicle (0.5% methyl cellulose/saline) or Pyributicarb (100 mg/kg/day) is administered p.o. for 2 consecutive days. Animals are killed 20 h after the last dose[1].

Pyributicarb, a carbamate-type herbicide, is a potent activator of both CYP3A4 gene and human pregnane X receptor (hPXR).

Pyributicarb, a carbamate-type herbicide, is a potent activator of both CYP3A4 gene and human pregnane X receptor (hPXR). Pyributicarb is found to increase the CYP3A4 reporter activity at 0.1 to 1 μM more strongly than typical CYP3A4 inducer rifampicin. Expression of hPXR-siRNA clearly diminishes the Pyributicarb-stimulated CYP3A4 reporter activity in 3-1-10 cells and decreases the endogenous CYP3A4 mRNA levels in HepG2 cells[1]. Pyributicarb induces luciferase transcription via hPXR at low concentrations in the order of 10 nM. The relative potency of Pyributicarb for hPXR is 8.6-fold that of rifampicin (RIF)[2].

Pyributicarb causes enhancement of CYP3A4-derived reporter activity in mouse livers introduced with hPXR by adenovirus[1].

[1]. Matsubara T, et al. Assessment of human pregnane X receptor involvement in pesticide-mediated activation of CYP3A4 gene. Drug Metab Dispos. 2007 May;35(5):728-33. [2]. Kojima H, et al. Comparative study of human and mouse pregnane X receptor agonistic activity in 200 pesticides using in vitro reporter gene assays. Toxicology. 2011 Feb 27;280(3):77-87.