Application of nonlinear chemical fingerprinting to identification, evaluation and clinical use of Glycyrrhiza

Nonlinear chemical fingerprinting is a new technique for analyzing traditional Chinese medicines (TCMs). We developed such a method and applied it to Glycyrrhiza, a significant TCM. Nonlinear chemical fingerprints were obtained for Glycyrrhiza from four different production areas, and for 14 other TCMs with similar induction time. The calculation of their similarities was based on similarity system theory. Using intuitive visual comparison of the data and the similarity calculation results, Glycyrrhiza was discriminated from the 14 other TCMs. There was a linear relationship between the content of active TCM components and the induction time. This was used to compare the content of active components in Glycyrrhiza from the four different production areas, and establish an equivalent-dose relationship for these four samples. This method provides a new tool for discrimination and evaluation of Glycyrrhiza, and a dosage reference for clinical application of Glycyrrhiza from the four regions studied.