Complete 1H-NMR and 13C-NMR spectral assignment of five malonyl ginsenosides from the fresh flower buds of Panax ginseng

BackgroundGinsenosides are the major effective ingredients responsible for the pharmacological effects of ginseng. Malonyl ginsenosides are natural ginsenosides that contain a malonyl group attached to a glucose unit of the corresponding neutral ginsenosides.MethodsMedium-pressure liquid chromatography and semipreparative high-performance liquid chromatography were used to isolate purified compounds and their structures determined by extensive one-dimensional- and two-dimensional nuclear magnetic resonance (NMR) experiments.ResultsA new saponin, namely malonyl-ginsenoside Re, was isolated from the fresh flower buds of Panax ginseng, along with malonyl-ginsenosides Rb1, Rb2, Rc, Rd. Some assignments for previously published 1H- and 13C-NMR spectra were found to be inaccurate.ConclusionThis study reports the complete NMR assignment of malonyl-ginsenoside Re, Rb1, Rb2, Rc, and Rd for the first time.