Ultrasensitive in situ tracing of the alkaloid Dioncophylline A in the tropical liana Triphyophyllum peltatum by applying deep-UV resonance raman microscopy
Frosch T; Schmitt M; Noll T
UV resonance Raman microspectroscopy was applied for a localization of the antiplasmodial naphthylisoquinoline alkaloid dioncophylline A in very low concentrations in different parts of the samples (e.g. in the roots) of the tropical liana Triphyophyllumpeltatum. The application of resonance Raman microspectroscopy was characterized by a very high sensitivity and selectivity. It was possible to assign the resonance Raman spectra of dioncophylline A dioncophylline C and dioncopeltine A by means of a combination of NIR Raman spectroscopy and DFT calculations. The UV resonance Raman spectra of T. peltatum are very well resembled by the spectra of dioncophylline A while they can be clearly distinguished from the spectra of dioncophylline C and dioncopeltine A. This distinction between the various naphthylisoquinolines was possible by the two modes at 1356 and 1613 cm-1. These two modes were assigned to C=C stretching and CH bending vibrations. The presented results of a highly sensitive and selective in situ localization of the active agent dioncophylline A in different parts of the plant material of T. peltatum are of high importance for the acquisition of new antimalarials and for plant science in general.