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

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 20-2000ng/ml (r(2)≥0.999) for all analytes. Furthermore, the sensitivity of gas chromatography-mass spectrometry revealed sufficient lower limit of quantitation and detection of 20ng/ml and 5ng/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 24h with no significant degradation after three freeze/thaw cycles. A small amount of the administered cinnamaldehyde had long half-life of 6.7±1.5h. 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.