Chemical constituents from the flowers of Cynanchum auriculatum Royle ex Wight

The present work was undertaken to investigate chemical constituents and chemotaxonomic significance from the flowers of Cynanchum auriculatum Royle ex Wight (C. auriculatum) by phytochemical methods. As a result, sixteen compounds including phenols (1–7), flavonoids (8–13), and others (14–16) were yielded, and their chemical structures were elucidated by NMR and MS analyses, together with the comparison with the published spectroscopic data. Notably, seven compounds (3, 5, 6, 10, 12, 15, and 16) were first isolated from the family Apocynaceae; while five compounds (7, 9, 11, 13, and 14) were reported from C. auriculatum for the first time. Additionally, the chemotaxonomic significance of isolated compounds was also discussed.