Rapid Identification of Calotropagenin Glycosides Using High-Performance Liquid Chromatography Electrospray Ionisation Tandem Mass Spectrometry

ABSTRACT Introduction Cardiac glycosides in Calotropis procera have therapeutic use as inhibitors of Na+/K+‐ATPase to regulate heart contractions. A large amount of research attention has been received by these compounds towards their identification and structural characterisation. In order to achieve rapid identification of cardiac glycosides in phytochemical extracts a liquid chromatography tandem mass spectrometry (LC‐MS/MS) method has been developed involving metal cationisation by post‐column addition of alkali salts for the unambiguous determination of their molecular weights. Objective Identification of cardiac glycosides in Calotropis procera leaf extract. Results Calotropagenin and its 10 glycosides were unambiguously identified. The daughter ions at m/z 387, 369, 359, 351, 341 and 323 in their MS/MS spectra were attributed to the calotropagenin aglycone unit. Conclusion High performance liquid chromatography in combination with electrospray ionization tandem mass spectrometry involving metal cationisation by post column addition of alkali salts was successfully utilised for the rapid identification of calotropagenin glycosides/derivatives in Calotropis procera extract. Copyright © 2011 John Wiley & Sons, Ltd. In order to achieve rapid identification of cardiac glycosides in phytochemical extracts a liquid chromatography tandem mass spectrometry (LC‐MS/MS) method has been developed involving metal cationisation by post‐column addition of alkali salts for the unambiguous determination of their molecular weights. Tandem mass spectra of protonated molecules provided additional structural information.