摘要
由于缺乏对照品,中药中三萜皂苷类成分的含量通常以比色法测定总皂苷含量来表征。但是,比色法专属性差,测定结果不够准确。因此,该文以木通皂苷为例探讨总三萜皂苷含量测定方法。采用HPLC测定木通药材酸水解产物中3种主要皂苷元阿江榄仁酸、常春藤皂苷元和齐墩果酸的含量。参考2015年版《中国药典》中银杏叶总黄酮醇苷的测定思路,以上述3种皂苷元含量之和乘以转换系数作为木通总三萜皂苷含量。LC-MS/MS分析结果显示mutongsaponin C和saponin PJI是木通中含有的2个最主要的三萜皂苷类化合物,且二者相对分子质量相同。因此,mutongsaponin C的相对分子质量与阿江榄仁酸、常春藤皂苷元和齐墩果酸相对分子质量的比值的均值被定义为转换系数。HPLC方法中采用ACE Excel 3 C18-AR色谱柱(4. 6 mm×150 mm,3μm)进行分离,甲醇-水(含有0. 04%冰醋酸和0. 02%三乙胺)为流动相,梯度洗脱,检测波长210 nm,流速0. 5 m L·min-1。结果显示阿江榄仁酸、齐墩果酸和常春藤皂苷元分别在1. 053~16. 84,0. 200~3. 200,1. 515~24. 24μg线性关系良好,平均加样回收率分别为97. 90%,97. 50%,100. 5%,RSD为2. 0%,2. 9%,2. 9%。方法学考察结果均符合含量测定要求。mutongsaponin C对3种皂苷元的转换系数的均值为2. 31。该方法简便,可靠,可用于木通药材中总三萜皂苷的含量测定,该思路可用于其他中药中总三萜皂苷的测定。
Due to lack of reference substances,the content of triterpenoid saponins in traditional Chinese medicines is usually characterized by colorimetric determination of total saponins. However,the specificity of colorimetric method is poor,and the determination result is not accurate enough. So,in this paper,the content determination method of total triterpenoid saponins was studied by taking Akebiae Caulis saponins as an example. The contents of three main saponin aglycones,including arjunolic acid,hederagenin and oleanolic acid,were determined by HPLC method. Referring to the content determination method of total flavonol glycosides in Ginkgo biloba leaves in the 2015 edition of Chinese Pharmacopoeia,the content of Akebiae Caulis saponins was obtained by multiplying the total content of the three above-mentioned aglycones with conversion coefficient. LC-MS/MS analysis results showed that mutongsaponin C and aponin PJIwere the two main triterpene saponins in Akebiae Caulis,and they shared the same molecular formula. So,the average value of the ratios of the molecular weight between mutongsaponin C and the three aglycones was defined as the conversion coefficient.The three aglycones were separated on an ACE Excel 3 C18-AR column( 4. 6 mm×150 mm,3 μm),and methanol-water( containing0. 04% glacial acetic acid and 0. 02% triethylamine) was used as mobile phase with gradient elution. The detection wavelength was set at 210 nm,and the flow rate was 0. 5 m L·min-1. The results showed that there was a good linearity among the ranges of 1. 053-16. 84,0. 200-3. 200 and 1. 515-24. 24 μg for arjunolic acid,hederagenin and oleanolic acid,respectively. Their average recoveries were97. 90%,97. 50% and 100. 5%,with RSD of 2. 0%,2. 9% and 2. 9%,respectively. The results of methodological investigation met the requirements of content determination. The conversion coefficient was 2. 31. This method is simple and reliable,and can be used for the determination of total triterpenoid saponins in Akebiae Caulis. The assay strategy can be used for the determination of total triterpenoid saponins in other traditional Chinese medicines.
引文
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