Development and validation of an LC-MS/MS method for quantification of NC-8 in rat plasma and its application to pharmacokinetic studies

Abstract

ent-16-Oxobeyeran-19-N-methylureido (NC-8) is a recently synthesized derivative of isosteviol that showed anti-hepatitis B virus (HBV) activity by disturbing replication and gene expression of the HBV and by inhibiting the host toll-like receptor 2/nuclear factor-κB signaling pathway. To study its pharmacokinetics as a part of the drug development process, a highly sensitive, rapid, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for determining NC-8 in rat plasma. After protein precipitation extraction, the chromatographic separation of the analyte and internal standard (IS; diclofenac sodium) was performed on a reverse-phase Luna C₁₈ column coupled with a Quattro Ultima triple quadruple mass spectrometer in the multiple-reaction monitoring mode using the transitions, m/z 347.31 → 75.09 for NC-8 and m/z 295.89 → 214.06 for the IS. The lower limit of quantitation was 0.5 ng/mL. The linear scope of the standard curve was between 0.5 and 500 ng/mL. Both the precision (coefficient of variation; %) and accuracy (relative error; %) were within acceptable criteria of <15%. Recoveries ranged from 104% to 113.4%, and the matrix effects (absolute) were non-significant (CV ≤ 6%). The validated method was successfully applied to investigate the pharmacokinetics of NC-8 in male Sprague-Dawley rats. The present methodology provides an analytical means to better understand the preliminary pharmacokinetics of NC-8 for investigations on further drug development.

Keywords: Isosteviol derivative; LC–MS/MS; NC-8; Pharmacokinetics.

Fig. 1

Chemical structures of stevioside, isosteviol, and NC-8.

Fig. 2

Parent and daughter mass spectra for NC-8 (a and b) and for internal standard (c and d).

Fig. 3

Chromatograms of (a) blank rat plasma; (b) the internal standard; (c) lower-limit of quantitation; (d) low quality control; (e) medium quality control, and (f) rat plasma concentration, 60 min after intravenous administration of a 2 mg/kg dose of NC-8.

Fig. 4

Calibration curve for NC-8 in rat plasma (n = 5).

Fig. 5

Mean plasma concentration–time curves of NC-8 in rats after intravenous (IV) and oral (PO) administration of a 2 mg/kg dose. Each point represents mean ± SD (n = 6).