同属不同种大黄及含大黄制剂中土大黄苷检查方法的研究

目的: 建立以土大黄苷为检查指标的薄层色谱法鉴别大黄及中成药中大黄的真伪;建立双波长荧光薄层扫描法测定目前市场上常见的2个大黄伪品,即华北大黄Rheum franzenbachii Munt.和河套大黄Rheum hotaoense C.Y. Cheng et C. T.中土大黄苷的含量测定。 方法: 以甲醇超声提取的方法制备供试品溶液,聚酰胺薄膜为固定相,甲苯-甲酸乙酯-丙酮-甲酸-甲醇(30∶ 5∶ 5∶ 0.1∶ 20)为展开剂展开,紫外光(365 nm)检视;薄层扫描法测定土大黄苷的含量,λ_S=328 nm,λ_R=398 nm。 结果: 土大黄苷在华北大黄、河套大黄薄层色谱中清晰检出,Rf_土大黄苷=0.4,在中国药典收载的正品大黄,即掌叶大黄Rheum palmatum L.、唐古特大黄Rheum tanguticum Maxim. ex Balf.和药用大黄Rheum officinale Baill.中未检出;土大黄苷点样量在2.0~50.0 ng范围内与扫描峰面积值呈良好的线性关系(r=0.9996,n=6);华北大黄中土大黄苷的平均回收率为98.0%(RSD=2.7%,n=6);河套大黄土大黄苷的平均回收率为98.4%(RSD=3.0%,n=6)。 结论: 该方法简便、准确,分离度高,重现性好,方法专属性强,可用于同属不同种大黄及其制剂中大黄的真伪鉴定,有实际应用价值。

Objective: To establish a method for identification of rhaponticin in the same family but of different species rhubarb and the preparation made from rhubarb by TLC,and determination of rhaponticin in two species of false rhubarbs which were common on the market by TLCS,Rheum franzenbachii Munt. and R. hotaoense C. Y. Cheng et C. T. Kao. Methods: The samples were treated by methanol;A polyamide film was used as the absorbent and a mixture of toluene,ethyl format,formic acid and methanol as the mobile phase(30∶ 5∶ 5∶ 0.1∶ 20);The spots were examined under UV 365 nm.Rhaponticin was assayed by dual wavelength TLC scanning method with 328 nm and 398 nm as the sample and reference wavelength respectively. Results: Rhaponticin was detected in R. franzenbachii and R.hotaoense.Rf_rhaponticin=0.4,and was undetected in the chromatogram of three official rhubarbs: R. palmatum L.,R. tanguticum Maxim. ex Balf.,and R. officinale Baill.;The methodological study showed a good linearity correlation at the range between 2.0-50.0 ng(r=0.9996,n=6);The average recovery of rhaponticin for R. franzenbachii was 98.0%( RSD=2.7%,n=6),and 98.4% (RSD=3.0%,n=6) for R.hotaoense. Conclusion: The identification method of TLC is simple,accurate and sensitivity,and has good specificity,high resolution and good reproducibility for the quality control of rhubarb and its preparation.