| Alkylamide from Zanthoxylum, one of the major active compounds present in Zanthoxylum, has showd a wide spectrum of biological and phatmacological effects including anti-inflammatory, analgesic, anesthetic, insecticide, anti-wrinkles, regulate gastrointestinal system and so on, which can be used in pharmaceutical and cosmetic industries. It is cheap as food for alkylamide from Zanthoxylum, while medicine has high economic value, so it worth to develop into a new drug. Compared to the extensive research of the pharmacological activities of alkylamide from Zanthoxylum, however, little is known of its pharmacokinetic and disposition properties in animals and humans. Pharmacokinetics study plays an important role in new drug development. Thus this thesis concerned with a study of the pharmacokinetics of alkylamide from Zanthoxylum in rats, so as to support the metabolism and pharmacokinetic study in human and to offer the reference for clinical dosag and dosage from chaning. The primary objectives of the present study were to characterize absorption, distribution, metabolism and excretion of alkylamide from Zanthoxylum by high performance liquid chromatography (HPLC-UV).1. A simple liquid-liquid extraction procedure and quantification by high-performance liquid chromatography (HPLC) method coupled to a ultraviolet detector (UV) of alkylamide from Zanthoxylum was developed according to the different characteristics of rat biological matrices. Schizandrin was used as internal standard and peaks were optimally separated using a Intersil ODS-SP C18column (5μm,250mm X4.6mm) at35℃with an isocratic elution of mobile phase with water and methanol (30:70, v·v-1) at a flow rate of0.5mL/min, The injection volume was20μL. A fast HPLC method with high recovery and good stability was successfully developed and validated for analysis the level of alkylamide from Zanthoxylum in rat matrices.2. The impact of different concentrations of alkylamide from Zanthoxylum on rat duodenum, jejunum, ileum and colon was studied by using the in situ intestine perfusion method in rats. The results showed that:The absorption rate constants (K) of alkylamide from Zanthoxylum were among0.0030and0.0065min-1at the concentration of25,50and100μg·mL-1, the absorption percentage between30.16%and56.81%. In the perfusate concentration range from25μg·mL-1and100μg·mL-1, the intestinal absorption mechanism of alkylamide from Zanthoxylum was conform to be passive trasport mechanism and fit to order kinetics. The absorption rate constants of alkylamide from Zanthoxylumin intestine was jejunum, ileum, duodenum, colon by turns, jejunum and ileum were major absorption segments.3. Tissue distribution of alkylamide from Zanthoxylum in rats after oral administration (40mg-Kg-1) was studied. Rats were serially euthanized by spondylopathy luxation after different minitues, heart, liver, spleen, lung, kidney, stomach, intestines, brain, skin, muscle, fat, testis and prostate were sampled. Results showed that five minutes after iv administration, alkylamide from Zanthoxylum was rapidly, extensively distributed to the various rat tissues, mainly in the stomach, fat, skin, muscle and liver. The highest concentration of alkylamide from Zanthoxylum was found in most tissues after30minutes ig administration, then decreased slowly. In addition, alkylamide from Zanthoxylum can across the blood-brain barrier and blood-testis barrier, it was easy to accumulate in fat, skin and epididymis, others were not.4. Excretion of alkylamide from Zanthoxylum in rat urine, bile and feces after oral administration was studied. It was shown that after a single oral administration, the accumulative excretion ammount of alkylamide from Zanthoxylum were about1375.72±69.16μg,15.66±0.96%in urine,485.69±89.49μg,5.30±1.24%in feces within72hours,1.45±0.35%in bile within36hours, respectively,22.41±2.55%in total. It showed that alkylamide from Zanthoxylum excreted basically by the unchanged drug from the urine and feces, which indicates an extensive metabolism of it in rats.5. The metabolic kinetics of alkylamide from Zanthoxylum, the effects of alkylamide from Zanthoxylum on hepatic microsome P450enzyme and protein content were investigated in rat liver microsomes. The results showed that the enzyme content in microsomes of liver, kidney and small intestine was not statistically significantly induced by alkylamide from Zanthoxylum, the content of hepatic microsome protein, CYP450and CYP b5were not affected by alkylamide from Zanthoxylum. Incubation time of30minutes, protein concentration of0.5mg-mL-1and substrate concentration of40μg·mL-1were found to be optimal for the metabolism of alkylamide from Zanthoxylum in rat liver microsomes. Under these optimal conditions, the enzyme kinetic regression equation was y=2.6576x+0.1568(r=0.971), Vmax, Km and CLint for alkylamide from Zanthoxylum were6.38μg·mL-1·min-1·g-1protein,16.95μg·mL-1and0.38mL·min-1·g-1protein, respectively. |
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