Abstract: Spirasine Ⅲ, diterpene alkaloid, was isolated from the root of Spiraea japonica L. f. var. fortunei(phanchon) Rehd. Its structure was demonstrated by spectral and chemical methods. The assignment of proton and carbon in the structure as well as double signals in the oxazolidine ring were achieved on the basis of detailed 2D-NMR spectroscopic analyses.

Key words: NMR, spirasine Ⅲ, diterpene alkaloids, oxazolidine ring