Determination of trans-resveratrol and its metabolites in rat serum using liquid chromatography with high-resolution time of flight mass spectrometry

In this study we developed a sensitive method using high performance liquid chromatography (HPLC) coupled to electrospray ionization (ESI) with high resolution time of flight (TOF) mass spectrometry (MS) for the determination of naturally occurring antioxidant trans-resveratrol (3,5,4'-trihydroxy-transstilbene, RES). This method enabled an investigation of a relationship between tumor growth in rats and concentration of RES and its primary metabolites, trans-resveratrol-3-O-sulfate-3-O-sulfate (R3S) and trans-resveratrol-3-O-beta-D-glucuronide (R3G), in rat serum after RES exposure (5 or 25 mg/kg/day). RES levels in rat serum were near the limit of detection, showing concentrations of 4 +/- 1 and 12 +/- 4 ng/mL for low and high-dose exposure, respectively. Compared to RES, higher concentrations were found for its metabolites (R3G:4.8 +/- 0.3 and 6.8 +/- 0.3 mu g/mL; R3S:0.27 +/- 0.09 and 0.34 +/- 0.04 mu g/mL, respectively). Using TOF, for the first time, we measured the matrix affected limits of detection (LODs) in plasma (3.7, 82.4, and 4.7 ng/mL for RES, R3G, and R3S, respectively), which were comparable to those reported in previous work using HPLC tandem mass spectrometry, but with a benefit of a full mass spectral profile. The ability to acquire data in full scan mode also revealed other isomers of R3S. The additional novelty of our study is in synthesis and application of deuterated recovery standards enabling accurate and precise quantification. In order to develop a robust method, the ESI conditions were optimized using a multilevel full factorial design of experiments. (C) 2016 Elsevier B.V. All rights reserved.