Multivariate analysis of 1H NMR spectra for saponins from Quillaja saponaria Molina

The bark of the South American tree Quillaja saponaria Molina contains at least 100 different saponin structures. A set of known structures were classified by partial least squares regress ion-discriminant analysis (PLS-DA) on spectra from H-1 NMR. PLS-DA was found to detect structural variations in the different parts of the saponins, encoded in the spectra. The models obtained were used to classify a test set of known structures. The amount of saponin material used for the NMR spectroscopy was only 200 mug/sample. This means that the outlined method is an interesting tool in the structural analysis of minor saponin components from Quillaja. This non-destructive method could also be applied on and facilitate the analysis of other natural products and metabolites since only minor amounts of sample are needed. (C) 2001 Elsevier Science B.V. All rights reserved.