An LC-MS/MS method for quantitation of cyanidin-3-O-glucoside in rat plasma: Application to a comparative pharmacokinetic study in normal and streptozotocin-induced diabetic rats

A sensitive and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to determine cyanidin-3-O-glucoside (Cy-3G) in normal and streptozotocin-induced diabetic rat plasma. Chromatographic separation was carried out on a ZORBAX SB-C18 (50 mm × 4.6 mm, 5 μm) column and mass spectrometric analysis was performed using a Thermo Finnigan TSQ Quantum Ultra triple-quadrupole mass spectrometer coupled with an ESI source in the negative ion mode. Selected reaction monitoring (SRM) mode was applied for quantification using target fragment ions m/z 447.3→285.2 for Cy-3G, and m/z 463.0→300.1 for quercetin-3-O-glucoside (internal standard). Calibration curve was linear over the range of 3.00–2700 ng/mL (r2 ≥ 0.99) with the lower limit of quantitation (LLOQ) at 3.00 ng/mL. Intra- and inter-day precision was below 14.5% and mean accuracy was from –11.5% to 13.6%. Stability testing showed that Cy-3G remained stable during the whole analytical procedure. After validation, the assay was successfully used to support a preclinical pharmacokinetic comparison of Cy-3G between normal and diabetic rats. Results indicated that diabetes mellitus significantly altered the in vivo pharmacokinetic characteristics of Cy-3G after oral administration in rats.