Analysis of Ginsenosides in Sheng-Mai-Yin Decoction by High Performance Liquid Chromatography-Diode Array Detection-Electrospray Mass Spectrometry

A method of high performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD/MS) in negative ion mode was developed for the analysis of ginsenosides in Sheng-Mai-Yin decoction (Panax gingeng C. A. Mey, Ophiopogon japonicus (Thunb.) Ker-Gawl, Shisandra chinensis (Turcz.) Baill.). The analyses were preformed on a reversed-phase C-18 column (4. 6 mm i. d. x 150 mm, 5 mu m) using a binary eluent (10 mmol/L ammonium acetate (A) and acetonitrile (B), 1 mL/min) under gradient conditions (60%A -40%A at 0 -30 min, 40%A -30%A at 30 - 40 min). Seventeen ginsenosides (20 (R) -Rh-1, Rh-2, Rg(3), Rg(2); 20(s) -Rh-1, Rh-2, Rg(3), Rg(2); Rf, Rg(6), Rg(5), F-4,F- Rk(1) Rk(3), Rh-4; 20 (s) - and 20 (R) -protopanaxatriol) were well separated and detected at 203 nm by a DAD detector. The effluent from the DAD detector was introduced into the electrospray ionization (ESI) source in a post-column splitting flow rate at 0. 3 mL/min. In the mass spectrum two major ions [M - H](-) and [M + AcO](-) were observed for ginsenoside standards (20 (R) -Rh-1, Rg(3), Rh-2; 20 (s)-Rh-1, Rg(3), Rh,; 20 (s) - and 20 (R) -protopanaxatriol) and ginsenosides in Sheng-Mai-Yin decoction. Some other ions [M - Glc - H](-), [M - 2Glc - H](-), [M - Rha - H](-) and [M - Rha - Glc - H](-) were also found in the mass spectrum of ginsenosides of Sheng-Mai-Yin decoction. In the decoction process ginsenosides changed into constituents of moderate and low polarity by hydrolysis, isomerization and dehydration at the site of C-20 and hydrolysis reaction also occurred at the site of C-3 or C-6. The work above presents a quick and accurate assay method which can could be used for the qualitative analysis of ginsenosides in Sheng-Mai-Yin decoction and the quality control of Sheng-Mai-Yin preparation.