Li Hong-Fu, Xu Feng, Yang Ping, Liu Guang-Xue, Shang Ming-Ying, Wang Xuan, Yin Jun, Cai Shao-Qing
School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, No. 103 Wenhua Road, Shenyang 110016, China; State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, No. 38 Xueyuan Road, Beijing 100191, China.
State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, No. 38 Xueyuan Road, Beijing 100191, China.
J Pharm Biomed Anal. 2017 Aug 5;142:102-112. doi: 10.1016/j.jpba.2017.05.009. Epub 2017 May 5.
Astragalosides (AGs) are the main bioactive constituents in Astragali Radix (AR), and have a wide range of pharmacological properties, including immunoregulatory, cardioprotective, neuroprotective, antioxidative, antidiabetic, and antinociceptive effects. However, the metabolism of total AGs remains unclear. To clarify the metabolic fate of AGs after oral administration to rats, total AGs were isolated from AR extracts using AB-8 macroporous resin chromatography and preparative HPLC, and then analyzed using HPLC-DAD-ELSD and LC-MS. HPLC-ESI-IT-TOF-MS was used to systematically screen and characterize prototype constituents and metabolites of total AGs in rat feces, urine, and plasma samples. As a result, 123 AG-related compounds from feces were detected and structurally characterized. Among the 123 compounds, 107 were phase I metabolites, of which 91 were new metabolites, and 73 were new compounds. In addition, six prototype constituents in urine, and one in plasma were detected. The main metabolic sites in the structure of cycloastragenol (CAG), the aglycone of AGs, were found to be the 9, 19-cyclopropane ring (E ring) and the 20, 24-furan ring (F ring). The cleavage mode of CAG derivatives in negative ion mode was identified, and was found to be highly dependent on the integrity of the E ring. Mono- to tetra-hydroxylated and carboxyl substituted metabolites were tentatively identified. Deglycosylation, hydroxylation, dehydrogenation, isomerization, ring cleavage, and carboxyl substitution were considered to be the major metabolic reactions involved in the formation of the metabolites, among which carboxyl substitution was a novel metabolic reaction. In summary, after total AGs were orally administered to rats, their constituents were extensively metabolized in a phase I manner, and the metabolites were excreted mainly into feces. To our knowledge, this is the first systematic study on the metabolism of total AGs. The results give us insight into the metabolic profiles of total AGs in vivo, and provide a foundation for identifying effective forms of AGs and exploring their mechanism in future studies.
黄芪皂苷（AGs）是黄芪（AR）中的主要生物活性成分，具有广泛的药理特性，包括免疫调节、心脏保护、神经保护、抗氧化、抗糖尿病和抗伤害感受作用。然而，总AGs的代谢情况仍不清楚。为了阐明AGs经口给予大鼠后的代谢命运，采用AB-8大孔树脂柱色谱和制备型高效液相色谱从AR提取物中分离出总AGs，然后用高效液相色谱-二极管阵列检测器-蒸发光散射检测器（HPLC-DAD-ELSD）和液相色谱-质谱联用仪（LC-MS）进行分析。采用高效液相色谱-电喷雾离子化-离子阱-飞行时间质谱（HPLC-ESI-IT-TOF-MS）系统地筛选和鉴定大鼠粪便、尿液和血浆样品中总AGs的原型成分和代谢产物。结果，从粪便中检测到123种与AG相关的化合物并对其进行了结构表征。在这123种化合物中，107种为I相代谢产物，其中91种为新的代谢产物，73种为新化合物。此外，在尿液中检测到6种原型成分，在血浆中检测到1种。发现AGs的苷元环黄芪醇（CAG）结构中的主要代谢位点是9,19-环丙烷环（E环）和20,24-呋喃环（F环）。确定了CAG衍生物在负离子模式下的裂解方式，发现其高度依赖于E环的完整性。初步鉴定出单羟基至四羟基以及羧基取代的代谢产物。去糖基化、羟基化、脱氢、异构化、环裂解和羧基取代被认为是代谢产物形成过程中的主要代谢反应，其中羧基取代是一种新的代谢反应。综上所述，总AGs经口给予大鼠后，其成分以I相方式广泛代谢，代谢产物主要排泄到粪便中。据我们所知，这是首次对总AGs的代谢进行系统研究。这些结果使我们深入了解了总AGs在体内的代谢概况，并为今后研究中鉴定AGs的有效形式及其作用机制提供了基础。
