Discrimination of Solanaceae taxa and quantification of scopolamine and hyoscyamine by ATR-FTIR spectroscopy.

Plant species of the Solanaceae family (nightshades) contain pharmacologically active anticholinergic tropane alkaloids, e.g., scopolamine and hyoscyamine. Tropane alkaloids are of special interest, either as active principles or as starting materials for semisynthetic production of other substances. For genetic evaluation, domestication, cultivation, harvest and post-harvest treatments, quantification of the individual active principles is necessary to monitor industrial processes and the resulting finished products. Up to now, frequently applied methods for quantification are based on high performance liquid chromatography and gas chromatography optionally combined with mass spectrometry. However, alternative analytical methods have the potential to replace the established standard methods partly. In this context, attenuated total reflection-Fourier transform infrared spectroscopy enabled chemotaxonomical classification of the Solanaceae Atropa belladonna, Datura stramonium, Hyoscyamus niger, Solanum dulcamara, and Duboisia in combination with cluster analysis. Also discrimination of genotypes within species was achieved to some extent. The most characteristic scopolamine bands could be identified in attenuated total reflection-Fourier transform infrared spectra of Solanaceae leaves, which allow a fast characterisation of plants with high scopolamine content. Applying a partial least square algorithm, very good calibration statistics were obtained for the prediction of the scopolamine content (residual prediction deviation = 7.67), and moderate prediction quality could be achieved for the hyoscyamine content (residual prediction deviation = 2.48).