Comparison on FTIR Spectrum and Thermal Analysis for Four Types of Rehamnnia Glutinosa and Their Extracts

Rehmannia glutinosa ( R. glutinosa ) is a plant material and widely used clinically in China. Due to different processing methods and various healing effects, there are four types of R. glutinosa s (RR, RRP, RRC, and RRPC) and their corresponding extracts for convenient use. As complicated mixture systems, chemical components of R. glutinosa are very difficult to identify and discriminate. In order to effectively control its quality during processing, Fourier transform infrared spectroscopy (FTIR), second derivative spectrum, and thermal analysis were used in this study. It was found that the major active ingredients were retained in the extracts when extracted from their corresponded R. glutinosa and subtle differences could be distinguished by the second derivative spectrum. FTIR spectrum, second derivative spectrum, and thermal analysis are valid method to validate and identify plant material, traditional Chinese medicine material, as well as their corresponding extracts.