Application of Fourier Transform Infrared Microspectroscopy (FTIR) and Thermogravimetric Analysis (TGA) for quick identification of Chinese herb Solanum lyratum

Solanum lyratum is a medicinal plant used to treat cancers and tumors. The objective of this study was to apply Fourier transform infrared microspectroscopy (FTIR) and thermogravimetric analysis (TGA) to quick identification of S. lyratum fourteen samples from its main geographic origins in China. The hierarchical dendrogram based on principal component analysis (PCA) of FTIR and TGA data showed that these samples could be divided into three ecotypes according to their geographic distances to the ocean: inland type, middle type and inshore type. Differences in cell compositions and structures by FTIR and TGA indicated that higher content of cell wall polysaccharides, hermo-oxidative degradation of hemicellulose (HODH) and degradation of lignin (DL) are appointed for inshore type compared to inland type and middle type. These indices (cell wall polysaccharides, HODH and DL) can be characteristic values for identifying S. lyratum from different region in China. The FTIR-TGA method, providing compositional and structural differences in their macromolecules in cell for the herbs rapidly and accurately, would be capable of further identification of other Chinese medicinal plant.