ABSTRACT
Objective To isolate and elucidate the structures of alkaloids in Huangyangning. Methods Alkaloids of Huangyangning were separated with preparative HPLC. The molecular structures were elucidated on the basis of chemical evidences and spectral analyses (UV, IR, MS, 1H-NMR, 13C-NMR, COSY, DEPT, HMQC, and HMBC). Results Cyclovirobuxine D is the major component in Huangyangning and cyclobuxine D and cyclovirobuxine C are the two related alkaloids. Conclusion It is demonstrated that all the Huangyangning alkaloids have the same structural frame with only minor differences in substitution through chromatographic and spectral analyses. Therefore, it is not easy to purify cyclovirobuxine D by using usual column, re-crystallization, or chemical approaches for the existence of the related alkaloids.