From the alcohol extract of the stem and root barks of the Chinese traditional medicinal plant, D. giraldii (Thymelaeaceae), a new bioactive diterpene, daphnegiraldifin (I), C43H60O9, white amorphous powder), was isolated in 0.00093% yield. Besides, two known bioactive diterpenes and a coumarin were also isolated and identified as daphnetoxin, 12-hydroxydaphnetoxin, and daphnoretin. Their structures were elucidated according to UV, IR, mass, and 1H NMR spectra and chem. evidence. I, daphnetoxin, and hydroxydaphnetoxin are skin irritants.

Key words: CRYSTAL STRUCTURE DETERMINATION, BIOLOGICAL ACTIVITY, MASS SPECTROGRAPHY, PROTON MAGNETIC RESONANCE SPECTROMETRY, DITERPENES, THYMELAEEACEAE, DICOUMAROLUM