Semen Ziziphi Spinosae (jujube seeds), the dried semen of Ziziphus jujuba MILL. var. spinosa (BUNGE) HU ex H. F. CHOU, is one of the most famous traditional Chinese medicines (TCMs) with hypnosis, sedation, and anticonvulsivant effects.1) It has been widely used for the treatment of insomnia in clinical practice.2) Chemical investigations on jujube seeds resulted in the discovery of several groups of bioactive components including flavonoids, saponins, and fatty acids. 3,4) Modern pharmacological studies have demonstrated that flavonoids are the main bioactive compounds responsible for the sedative and hypnotic effects of jujube seeds. 2,5) Hence it is important to explicate the biotransformation of flavonoids in vivo so as to clarify the mechanism of pharmacological action and to promote its availability as well. To date, there are few reports regarding the physiological disposition of flavonoids after oral administration of jujube seeds-containing TCMs 6,7) ; however, the biotransformation of flavonoids in vivo remains unknown. The challenges for the metabolic study in vivo of TCMs extract lie in two aspects: one is the complexity of TCMs containing hundreds of constituents, and the other is the lack of proper analytical methods for the identification of the metabolites even in trace amount.
8)A major goal of this study was to develop a highly specific and sensitive high-performance liquid chromatography method coupled with diode-array detection and ion-trap mass spectrometry (HPLC-DAD-MS n ) for the study of the constituents and metabolites in rat plasma, urine, and feces after oral administration of flavonoid extract of jujube seeds, providing scientific plausibility for the activity of this extract. These achievements would support preclinical pharmacokinetic studies and achieve a better understanding of the pharmacological action mechanism of flavonoid extract of jujube seeds.
ExperimentalMaterials Jujube seeds were purchased from a genuine area Xintai (Hebei, China) and identified by one of the authors, Dr. Ping Li. Spinosin (with a purity of 99.0%), and 6ٞ-feruloylspinosin (with a purity of 99.0%) (Fig. 1) was prepared in our laboratory. Male Sprague-Dawley (SD) rats were acquired from the Laboratory Animal Center of China Pharmaceutical University (Nanjing, China). HPLC grade acetonitrile was purchased from Merck KGaA Company (Merck, Germany). Deionized water was purified by Milli-Q system (Millipore, U.S.A.). Physiological saline was purchased from Shijiazhuang Pharmaceutical Corporation (Shijiazhuang, China). Heparin sodium, obtained from Hanbang Science & Technology (Nanjing, China), was dissolved in physiological saline at a concentration of 1250 U/ml and used to rinse the test tubes prior to blood collection for plasma. Glacial acetic acid, as well as the other reagents, was of analytical grade.Preparation of Flavonoid Extract from Jujube Seeds Jujube seeds (3.0 kg) were ground into powder (particle size 20-40 mesh) and refluxed with 24 l of petroleum ether (60-90°C) three times (each for 12 h). Af...