In vivo pharmacokinetics and pharmacodynamics study
Non-fasting C57BL/6J mice were orally administered CDDO-Me at doses of 3 and 10 mg・kg-1. Blood samples were collected via the abdominal vein into blood collection tubes containing EDTA-2K (Terumo Corp, Tokyo, Japan) under anaesthesia at 1, 4, 6, and 24 h after oral administration. Liver samples were also collected to analyse the expression of Nqo1 using quantitative PCR. The plasma concentration of CDDO-Me was measured using the API 3200 triple quadrupole mass spectrometer (AB Sciex LLC., Redwood City, CA) under the following conditions: column, Kinetex C18 (Phenomenex Inc., Torrance, CA, 50 × 2.1 mm, 2.6 μm); column temperature, 40 °C; flow rate, 0.4 mL・min-1; mobile phase A, 0.1% formic acid/MilliQ aqueous solution; mobile phase B, 0.1% formic acid in 50 v・v-1% acetonitrile/methanol solution; and gradient – 0 min: A / B=90 / 10, 1 min: A / B=10 / 90, 1-3 min: A / B=10 / 90, 3.01 min, A / B: 90 / 10. CDDO-Me was quantified in the negative ionization mode using multiple reaction monitoring with niflumic acid as the internal standard, as previously described (Resham et al., 2015). Data were acquired and integrated using Analyst software version 1.7 (AB Sciex LLC., RRID: not yet assigned).