Troglitazone (Romglizone) is a PPARγ agonist with anti-inflammatory and anti-tumor activity.

PPARγ (human):550 nM (EC50), PPARγ (murine):780 nM (EC50)

Troglitazone inhibits the growth of 786-O and A498 cells with EC50 values of 5.71 μM and 8.38 μM. Troglitazone(5 μM) significantly inhibits the CYP2C8-dependent paclitaxel 6a-hydroxylation and CYP2C9-dependent S-warfarin 7-hydroxylation. Troglitazone extensively suppresses CYP2C19-dependent S-mephenytoin 4′-hydroxylation and CYP3A4-dependent testosterone 6b-hydroxylation and moderately influences the CYP1A2- and CYP2B6-dependent 7-ethoxycoumarin O-deethylation, CYP2A6-dependent coumarin 7-hydroxylation and CYP2D6-dependent bufuralol 1′-hydroxylation. CYP2E1-dependent 7-ethoxycoumarin O-deethylation is not inhibited.

Local hypoxia is observed in liver but not in adipose tissue in troglitazone-treated mice. A significant increase in Ki-67/CD31 LI in liver, BAT, and WAT is observed in the 400 mg/kg troglitazone group. Troglitazone reduces the incidence of diabetes by 16 weeks compared to controls, when administered by gavage from weaning at a dose of 400 mg/kg body weight.

Standard incubation mixtures (final volume of 0.20 mL) containe recombinant P450 (0.010 μM) in 50 mM potassium phosphate bu?er (pH 7.4) containing an NADPH-generating system (0.5 mm NADP+, 5 mM glucose 6-phosphate, 0.5 unit glucose 6-phosphate dehydrogenase/mL) and substrates (1±100 lM). For determination of CYP1A2, CYP2B6, CYP2E1 and CYP3A4 activities, 100 mM potassium phosphate buffer (pH 7.4) is used. When human liver microsomes are used as the enzyme source, 500, 25, 100 and 25 pmol totalP450 per mL are used for paclitaxel 6a-hydroxylation, S-warfarin 7-hydroxylation,S-mephenytoin 4′-hydroxylation and testosterone 6b-hydroxylation respectively.

Troglitazone is made at 100 mM concentration in DMSO and added to the culture medium at the final concentration of less than 0.1%. The effect of PPARγ ligands on cell proliferation of RCC cells is determined using MTT assay. Briefly, cells of 0.5×l04 cells/well are inoculated into a 96-well plate, treated with pioglitazone or troglitazone at various concentrations. After an incubation for 24 h, 20 μL/well 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT, 5 g/L) is added to each well, the medium is then removed, and 200 μL of 0.04mol/LHCl in isopropanol is added to dissolve the reduced formazan product. The plate is read in a microplate reader at 590 nm.