Pharmacokinetic study of cinnamaldehyde in rats by GC–MS after oral and intravenous administration

•A new method is described to simultaneously quantify cinnamaldehyde and its metabolites.•The pharmacokinetic parameters of cinnamaldehyde and its metabolites are determined.•A new metabolite methyl cinnamate was determined.•Pharmacokinetic study showed that a small portion of cinnamaldehyde sustained a low concentration for a long time.

A selective and sensitive method utilizing gas chromatography–mass spectrometry was developed for simultaneous determination of cinnamaldehyde, cinnamyl alcohol, and methyl cinnamate in rat plasma. Cinnamaldehyde and cinnamyl alcohol can inter-convert to one another in rats, thus simultaneous quantifying both analytes provided a reliable and accurate method of assessment. Three qualifying ions (131 m/z, 105 m/z and 92 m/z) were chosen for simultaneous quantification of cinnamaldehyde and its metabolites. In this study, the calibration curves demonstrated a good linearity and reproducibility over the range of 20–2000 ng/ml (r2 ≥ 0.999) for all analytes. Furthermore, the sensitivity of gas chromatography–mass spectrometry revealed sufficient lower limit of quantitation and detection of 20 ng/ml and 5 ng/ml, respectively, in the pharmacokinetic analysis. The intra- and inter-day precision variations were less than 10.4% and 12.2%, respectively, whilst accuracy values ranged from −8.6% to 14.8%. All analytes were stable in plasma and in processed samples at room temperature for 24 h with no significant degradation after three freeze/thaw cycles. A small amount of the administered cinnamaldehyde had long half-life of 6.7 ± 1.5 h. In this study, gas chromatography–mass spectrometry was demonstrated to be a powerful tool for the pharmacokinetic studies of rats after intravenous and oral administration of cinnamaldehyde.

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