Short communicationPlasma pharmacokinetics, tissue distribution and excretion study of 6-gingerol in rat by liquid chromatography–electrospray ionization time-of-flight mass spectrometry
Introduction
Ginger, the rhizome of Zingiber officinale Roscoe, is widely used as a spice in a variety of foods and beverages. In addition, fresh or processed ginger has been used in Traditional Chinese Medicine for many ailments [1]. The major pungent constituent of ginger is 6-gingerol [2], [3]. It has been found to possess a variety of effects [4], [5], [6], [7], [8], and recent studies in animal models showed that 6-gingerol could suppress carcinogenesis in skin [9], gastrointestinal tract [10] and breast [11]. Although the mechanism of 6-gingerol in carcinogenesis is not yet clear, some studies revealed that nuclear factor-κB is related to the chemopreventive effect of 6-gingerol [12], [13], [14].
Comparing the abundant pharmacological studies, few reports were related to the determination of 6-gingerol. High-performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) [2], [15] was reported for the qualitative analysis of ginger extract. HPLC methods coupled with UV or electrochemical detection were also developed for the determination of 6-gingerol in ginger-containing products [3], plasma [16], [17], [18], tissues [19] or simulated gastric and intestinal fluids [20]. Limited sensitivity of current quantitative methods is the major obstacle for oral pharmacokinetic study, and none of them was applied to the tissue distribution or excretion study of 6-gingerol after oral administration of 6-gingerol. The combination of sub-2 μm material columns with dedicated purpose-built instrumentation (e.g., rapid resolution LC from Agilent and ultra-performance LC from Waters) allows faster separations with excellent peak capacities and daily sample capability for pharmacokinetic research [21], [22], metabonomics study [23], and herbal prescription analysis [24]. In our study, a sensitive and specific rapid resolution LC–ESI-TOF/MS method was developed and validated for the estimation of 6-gingerol in different biological matrices to support the development of 6-gingerol. As the phase II metabolism of 6-gingerol may be of importance in pharmacological and toxicological consideration [25], [26], we also tried to determine the glucuronide of 6-gingerol in plasma, tissues and urine. This analytical method was successfully applied to plasma pharmacokinetics, tissue distribution and excretion study of 6-gingerol in rats for the first time.
Section snippets
Chemicals
Authentic standard of 6-gingerols was purchased from ChromaDex (Santa Ana, CA, USA). Nonivamide (>98%) was provided by Qingdao Haida Chemical Co. Ltd. (Qingdao, China). The purity of 6-gingerol used in our study was determined to be higher than 98% by HPLC–UV method compared with the standard reference.
Acetonitrile (HPLC grade) was purchased from Merck (Darmstadt, Germany), and β-glucuronidase (1,000,000–5,000,000 units/g protein, type IX-A, from Escherichia coli) was purchased from
HPLC–MS analysis
The MS spectra of 6-gingerol, 6-gingerol glucuronide and IS are shown as Fig. 2. The most abundant fragmentation ions of 6-gingerol at m/z 277.17 ([M+H–H2O]+) was selected for quantification under extracted ion chromatogram (XIC) mode in a mass window of m/z 277.13–277.22. HPLC–MS analysis of the blank and spiked plasma samples showed no endogenous peak interference with the quantification of 6-gingerol and the IS. In order to improve ionization efficiency and peak shape, 0.1% formic acid was
Conclusion
In our research, a rapid resolution LC–ESI-TOF/MS method was developed and validated for quantitative analysis of 6-gingerol in plasma, urine and tissue samples for the first time, and the LLOQ was better than current HPLC–UV methods. An extensive first-pass metabolism was observed. The plasma concentration and AUC(0−tn) of 6-gingerol glucuronide were substantially higher than 6-gingerol without reference to administration dosage or manner, while nearly all the publications related to the
Acknowledgement
The work was financially supported by Key Program of the National Science Foundation of China (No. 30530870).
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