Study on the Stability of Six Alkaloids in Uncaria Decoction

OBJECTIVE To develop an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for determination of hynchophylline, isorhynchophylline, isocorynoxeine, corynoxeine, hirsutine and hirsuteine in Uncaria decoction, and investigate the effect of different storage conditions on the stability of active ingredients. METHODS An UHPLC-MS/MS method was established to investigate the effects of different storage temperature and time on the stability of six active components in Uncaria decoction. Separation was performed with a gradient mobile phase system of acetonitrile-0.1% formic water solution, the flow rate was 0.4 mL·min^-1, the temperature of column was 30℃, the injection volume was 2 μL, the MS detection was dynamic multiple reaction monitoring mode. The effects of different storage temperature and time on the stability of six active components in Uncaria decoction was investigated. RESULTS Rhynchophylline, isorhynchophylline, corynoxeine, isocorynoxeine, hirsutine and hirsuteine were successfully separated using this method, with good linear relationship in the corresponding concentration range. The precision, repeatability, stability and recovery rate were good. The six alkaloids were basically stable within 14 d under low temperature storage, basically stable within 3 d under normal temperature storage, and not stable under high temperature storage. CONCLUSION The UHPLC-MS/MS method is stable, rapid and reproducible. It can be used to determine the contents of six effective components in Uncaria decoction. Cold storage is beneficial to the stability of Uncaria decoction.