Euphiquorins A-E, five new structurally diverse diterpenoids from Euphorbia antiquorum L.
Phytochemical investigation of the whole plant of Euphorbia antiquorum led to the isolation of sixteen diterpenoids, including five new compounds, euphiquorins A-E (1, 5-8), together with eleven known analogues (2-4, 9-16), which were elucidated by comprehensive spectroscopic analyses and quantum chemical calculations.