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Sandasi, M., Vermaak, I., Chen, W., Viljoen, A.M. 2014. Hyperspectral imaging and chemometric modeling of Echinacea - a novel approach in the quality control for herbal medicines. Molecules 19: 13104-13121.
Echinacea species are popularly included in various formulations to treat upper
respiratory tract infections. These products are of significant commercial importance with a collective sales figure of $132 million in 2009. Due to their
close taxonomic alliance it is difficult to distinguish between the three Echinacea species and incidences of
incorrectly labeled commercial products have been reported. The potential of
hyperspectral imaging as a rapid quality control method for raw material and
products containing Echinacea species
was investigated. Hyperspectral images of root and leaf material of authentic Echinacea species (E. angustifolia, E. pallidaand E. purpurea) were acquired using
a sisuChema shortwave infrared (SWIR) hyperspectral pushbroom imaging system
with a spectral range of 920-2514 nm. Principal component analysis (PCA) plots
showed a clear distinction between the root and leaf samples of the three Echinacea species and further differentiated
the roots of different species. A classification model with a high coefficient
of determination was constructed to predict the identity of the species
included in commercial products. The majority of products (12 out of 20) were
convincingly predicted as containing E.
purpurea, E. angustifolia or
both. The use of ultra-performance
liquid chromatography-mass spectrometry (UPLC-MS) in the differentiation of the
species presented a challenge due to chemical similarities between the solvent
extracts. The results show that hyperspectral imaging is an objective and
non-destructive quality control method for authenticating raw material.