Abstract: Flower bud of Tussilago farfara L. is a widely used herbal medicine in the Traditional Chinese Medicine. However, due to the increasing demands, adulteration with rachis is frequently encountered in the marketplace. In this study, chemical differences and pyrrolizidine alkaloid contents of flower bud and rachis were compared. No report demonstrated the chemical and pharmacological differences between flower bud and rachis before. Chemical differences between flower bud and rachis were compared by GC-MS based on metabolic approach, and the metabolites were identified by NIST data base search and comparison with the authentic standards. The transformed data matrix was introduced into SIMCA-P 11.0 software for multivariate analysis. Content of pyrrolizidine alkaloid was determined by UPLC. 54 metabolites were identified by GC-MS, and the PCA analysis revealed the clear separation between the rachis and flower bud, indicating the obvious chemical differences existing between them. The loading plot of OPLS-DA indicated that the rachis contained less inositol, aromadendrene, stigmasterol, palmitic acid, and more sucrose and arachidonic acid. UPLC results revealed that the flower bud contained more senkirkine (102 μg·g^-1) than the rachis (64 μg·g^-1). Due to the obvious chemical differences between the flower bud and rachis, to guarantee the clinical effect, rachis should be picked out before use, and set the limit of rachis in the quality standards.

Key words: Tussilago farfara, flower bud, rachis, metabolic differences, pyrrolizidine alkaloids