Identification of Daphnane Diterpenoids from Flower Buds and Blooming Flowers of Daphne odora Using UHPLC-Q-Exactive-Orbitrap MS

Daphne odora is an evergreen shrub belonging to the Thymelaeaceae family that is widely cultivated as an ornamental garden plant. Its roots, leaves, and flowers have traditionally been used in Chinese medicine to treat pain, skin diseases, and rheumatism. While previous phytochemical studies have reported the presence of phenols, coumarins, biflavonoids, lignans, and daphnane diterpenoids in D. odora, its flowers remain largely unexplored. In the present study, the first comprehensive investigation of daphnane diterpenoids contained in the flower buds and blooming flowers of D. odora was conducted using ultra-high-performance liquid chromatography coupled with Q-Exactive-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Exactive-Orbitrap MS). A total of 30 daphnane diterpenoids were identified, including 12 previously unreported compounds, through detailed analysis of their retention times and MS/MS fragmentation patterns. Comparative profiling revealed that flower buds contained a higher abundance and greater diversity of daphnane diterpenoids than flowers. Furthermore, LC–MS-guided isolation enabled the purification of a novel compound, daphneodorin I (16), and its structure was elucidated through extensive physicochemical and spectroscopic analyses. Compound 16 represents the first daphnane diterpenoid with a Z-configured phenolic acyl moiety isolated from plants of the Thymelaeaceae family.