Keywords: Mori Cortex; benzofuran; isolation; identification; quality control; intestinal bacteria; hepatic metabolism Sang-Bai-Pi (Mori Cortex), the root bark of Morus alba L., was recorded in the Pharmacopoeia of the People’s Republic of China (2010 edition) for relieving cough and asthma. The benzofurans, stilbenes and flavonoids in Mori Cortex are considered as bioactive components. Previous reports have shown that the benzofurans, stilbenes and flavonoids all exhibited strong anti-oxidation effect and that the benzofurans exert potent anti-virus, anti-microbiotic, hypoglycemic and inhibit tyrosinase activities. Researches in recent years mainly focus on the pharmacological study and chemical isolation of benzofurans; however, the content of benzofurans in Mori Cortex and metabolism characteristic are still unclear. The present study aims to elucidate the content of benzofurans in traditional Chinese medicine ―Sang-Bai-Pi‖ and also to reveal the metabolism characteristic of benzofurans in intestine and liver in vitro. During the first stage, we isolated and identified four main benzofurans from Mori Cortex by chemical approach, such as column chromatography, RP-HPLC LC-MS/MS and NMR. The purities of four compounds were analyzed by using HPLC-DAD. As a result, four main benzofurans were isolated and their structures were determined on the basis of spectroscopic evidence, which are moracin M, mulberroside C, moracin P and moracin O. Their purities were all greater than 98%, suggesting that they could be used as standard compounds for the present study. During the next stage, a HPLC-DAD method was developed and evaluated to carry out the content analysis of benzofurans in 9 batches of Mori Cortex bought from 6 regions. The results showed a good linearity between the investigated compounds’ concentrations and their peak areas within the test ranges and low RSD of peak areas in a 5-day period. It indicates that the method developed is precise and suitable for content analysis of benzofurans in Mori Cortex. The benzofurans in the 9 batches of Mori Cortex revealed remarkable differences in content, the highest being 0.1283%, while the lowest being 0.0025%. The intestinal bacterial metabolism researches of benzofurans were carried out by anaerobically incubation in vitro. A HPLC-DAD method was developed in this study. All the benzofurans were co-incubated with rat intestinal bacteria at 200 μg/mL as final concentrations. And the time points are 0,1,2,4,6,8,10 hours, the samples without bacteria or drugs were used as control groups. At this stage, the consequences are that the glycoside-mulberroside C got transformed into its aglycone-moracin P in 10 hours, but the aglycones-moracin P, moracin M and moracin O were not be converted, indicating that the aglycones were possibly absorbed forms of benzofurans in intestine. When the drugs were absorbed into blood by intestine, they got into liver by the hepatic portal vein; so it was of great importance to investigate the metabolism of drugs in liver. In the present study, we used rat liver microsomes co-incubated with benzofurans in vitro to elucidate the phase I metabolism and phase II glucuronidation of benzofurans in Mori Cortex. The results illustrated that the four benzofurans could not be metabolized by rat liver microsomes in phase I incubation system. However, for phase II glucuronidation, just mulberroside C could be glucuronidated by rat liver microsome in a minor extent. In conclusion, moracin M, mulberroside C, moracin P, moracin O are major benzofurans and also bioactive components in traditional Chinese medicine ―Sang-Bai-Pi‖. Through the intestinal bacterial conversion and hepatic metabolism study, we could infer that the benzofuran aglycones exert their anti-virus, anti-microbiotic, hypoglycemic and inhibit tyrosinase activities by their parent form, while the glycoside takes effect by its aglycone form.

關鍵字：桑白皮；苯并呋喃；化學分離；結構鑒定；品質控制；腸內菌轉化； 肝臟代謝 中藥桑白皮為桑科植物桑 Morus alba L.的乾燥根皮，其味甘，性寒，歸肺經， 主要功效為瀉肺平喘，利水消腫；臨床上，用於治療肺熱咳嗽，水腫脹滿，尿少， 面目肌膚浮腫等症。近年來的研究發現，桑白皮可以治療丙型肝炎，降低糖尿病 患者血糖水平，並且對黑色素的生物合成有一定的抑制作用。 桑白皮化學成分十分豐富，主要含苯并呋喃類，黃酮類和二苯乙烯類化合物。 近代科學研究表明，苯并呋喃類成分有很強的抗病毒，抗微生物活性，並且可以 降低血糖，且對黑色素的生物合成有明顯的抑制作用，是國內外的研究熱點。黃 酮類成分則具有抗氧化，舒緩平滑肌，拮抗鈣離子通道的作用，是桑白皮鎮咳平 喘作用的物質基礎。二苯乙烯類成分，對氧自由基有很強的清除作用，同樣具有 舒緩肺平滑肌的作用。 然而，由於桑科植物種類很多，化學成分差異較大，且目前都被作為桑白皮 生藥在市場上銷售流通，造成了桑白皮藥材的次品，偽品大量存在，且容易混淆， 使得某些市售的桑白皮藥材並不具有臨床治療的作用。這種狀況無疑影響了中藥的標準化和國際化。 目前，對桑白皮藥材中，具有抗病毒，降血糖活性的苯并呋喃類物質的品質 控制研究非常稀少，且其代謝特性也尚不清楚。 本研究通過化學手段分離並鑒定了中藥桑白皮中含量較大的四個苯并呋喃 類化合物，並建立了對此類物質的含量分析方法，比較了購自不同地區桑白皮藥 材中苯并呋喃類化合物的含量。此外，利用體外腸內菌孵育體系，肝微粒體一相 代謝及二相葡萄糖醛酸化孵育體系，對分離得到的這四個化合物進行了體外代謝 特性的研究，由此推測出桑白皮中苯并呋喃類成分在體內的吸收，代謝機制；旨 在探尋中藥桑白皮的物質基礎，為其提供簡便，可靠的品質控制方法，初步揭示 苯并呋喃類化合物的代謝特性，促進中藥新藥的開發；並且為―肺與大腸相表裡‖ 的中醫理論提供初步的科學證據，給以後的研究打下基礎。