| 摘要: | 穿心蓮(Andrographis paniculata)被視為藥用植物，穿心蓮內酯為穿心蓮主要活性植化物之一。先前研究指出穿心蓮或穿心蓮內酯具有降血糖、抗發炎、調節藥物代謝等生理功效，因此，在亞洲很多地區被廣泛應用於治療糖尿病及發炎等相關病症。Tolbutamide屬於磺醯尿素類之口服降血糖藥，應用在第二型糖尿病患者，主要透過肝臟中CYP2C9代謝成hydroxtolbutamide，再經alcohol dehydrogenase及aldehyde dehydrogenase作用後，排出體外。由於，很多人常將西藥與中藥或健康食品一起使用，尤其是老年者或長期服用慢性疾病藥物者，因此穿心蓮是否和西藥產生交互作用，進而影響西藥的藥效，必須嚴肅面對。本研究將探討穿心蓮乙醇萃出物(ethanolic extract of Andrographis paniculata, APE)與穿心蓮內酯(andrographolide, AND)對大鼠肝臟藥物代謝酵素和轉運蛋白活性與表現之影響，進而探討它們是否改變tolbutamide之藥物動力學參數。七週齡雄性Sprague Dawley大鼠分別每天胃管灌(i.g.) 2 g/kg APE (相當於166 mg/kg AND)或50 mg/kg AND，連續五天，第六天口服給予(p.o.) 20 mg/mL tolbutamide，採集0-12小時頸靜脈血液，隨後犧牲動物，取其肝臟。結果顯示：相較對照組，APE和AND處理顯著減少血漿中tolbutamide濃度曲線下面積(area under the curve, AUC)達69%及80% (p < 0.05)，各組間Tmax及Cmax差異雖未達顯著水準，但APE和AND組的Tmax及Cmax均低於對照組；肝臟藥物代謝酵素方面，相較對照組，APE和AND分別增加了肝臟ethoxyresorufin O-deethylase (CYP1A1)、methoxyresorufin O-demethylase (CYP1A2)、 diclofenac 4-hydroxylase (CYP2C)、p-nitrophenol 6-hydroxylase (CYP2E1)、and testersterone 6β-hydroxylation and midazolam 1-hydroxylase (CYP3A)及UDP-glucurosyl transferase (UGT) 酵素活性(p < 0.05)。免疫墨漬法及RT-PCR結果指出，APE與AND增加CYP1A1、1A2、2C6、2C11、3A1、3A2、UDP-glucuronyl transferase 1A1 (UGT1A1) 和πform Glutathione S-transferase (GSTP)之蛋白質及mRNA含量 (p < 0.05)；此外，APE也增加P-glycoprotein之蛋白質及mRNA含量(p < 0.05)。進一步EMSA分析也顯示APE和AND可增加轉錄因子PXR、AhR的DNA結合活性。除藥物代謝外，本實驗亦同時分析APE與AND對肝臟heme oxygenase 1 (HO-1)、glutamate-cysteine ligase catalytic subunit (GCLC)、glutamate-cysteine ligase modulatory subunit (GCLM)等抗氧化酵素之表現，結果明顯指出HO-1 mRNA及蛋白質表現均因APE和AND的處理而增加(p < 0.05)。以上結果指出APE和AND可能透過上調藥物代謝酵素基因的轉錄作用與活性，加速tolbutamide的代謝，改變tolbutamide的藥物動力學，因而改變tolbutamide的藥效。
Andrographis paniculata has been treated as a medicinal herb in many Asia countries for hundreds of years. Andrographolide, a diterpene lactone, is the most well known active phytochemical in Andrographis paniculata. Andrographis paniculata and andrographolide display many biological activities including anti-diabetes, anti-inflammation, and modulation on drug metabolism. Tolbutamide is an hypoglycemic drug for type II diabetes mellitus patient. cytochrome P450 (CYP) 2C9 is the main CYP isozyme responsible for hydroxylating tolbutamide to hydroxytolbutamide, which is then further oxidized by alcohol dehydrogenase or aldehyde dehydrogrnase. Currently, many consumers especially those with chronic diseases and elderlys commonly co-administered with drugs and herbs/healthy foods. It is interesting to know whether andrographis paniculata interacts with drug metabolism, thereby interferes the pharmacokinetics of drug. In this study, we investigated the effects of ethanolic extract of Andrographis paniculata (APE) and andrographolide (AND) on activity and expression of drug metabolizing enzymes and transporters in rat livers and also on the pharmacokinetic parameters of tolbutamide. Seven weeks-old male Sprague Dawley rats were intragastrically (i.g.) administered 2 g/kg/d APE (equivalent to 166 mg/kg AND) or 50 mg/kg/d AND for 5 days. At day 6, rats were intragastrically treated 20 mg/kg tolbutamide follwed by withdrawing blood at different time intervals for 12 h. Rats were then sacrificed and the livers were removed immediately. As compared to the control rats, APE and AND significantly reduced plasma tolbutamide concentration area under the curve (AUC) by 69% and 80% (p < 0.05), respectively. APE and AND tended to decrease Tmax and Cmax, although the differences were not reached significance. Enzyme actrivity assay reveals that hepatic ethoxyresorufin O-deethylase (CYP1A1), methoxyresorufin O-demethylase (CYP1A2), diclofenac 4-hydroxylase (CYP2C), p-nitrophenol 6-hydroxylase (CYP2E1), and testersterone 6??-hydroxylation and midazolam 1-hydroxylase (CYP3A) and UDP-glucurosyl transferase (UGT) activities were higher in rats dosed with APE and AND than that of controls (p < 0.05). In consistence to the changes on enzyme activity, immunoblots and RT-PCR indicated that APE and AND increased CYP 1A1, 1A2, 2C6, 2C11, 3A1, and 3A2 and UGT1A1 and the ?? form of glutathione S-transferase protein and mRNA levels (p < 0.05). In addition, protein and mRNA expression of the membrane transporter P-glycoprotein were up-regulated by APE (p < 0.05). EMSA demonstrated that APE and AND enhanced the DNA binding activity of pregnane X-receptor (PXR) and aryl hydrocarbon receptor (AhR). Regarding to the expression of antioxidant enzymes in rat livers, results indicated that heme oxygenase 1 mRNA and protein levels were increased by APE and AND (p < 0.05). These results suggest that APE and AND are effective on up-regulating gene transcription and enzyme activity of drug-metabolizing enzymes, which accelerate the metabolism of tolbutamide. |
