Tumor‐Promoting Diterpene Esters from Latex of Euphorbia cauducifolia L.

AbstractTumor‐promoting characteristics of seven esters, 1–7, obtained from the latex of Euphorbia cauducifolia L. was appraised by carrying out NMRI mice back skin. The structures of 1–7 were elucidated by spectroscopic techniques like 1H‐ and 13C‐NMR, 2D‐NMR (HMQC, HMBC, HOHAHA (homonuclear Hartmann–Hahn), NOESY, and NOE), FT‐IR, UV, and MS as esters of 17‐hydroxyingenol, namely 17‐[(2Z,4E,6Z)‐deca‐2,4,6‐trienoyloxy]ingenol (1), 3‐O‐angeloyl‐17‐[(2Z,4E,6Z)‐deca‐2,4,6‐trienoyloxy]ingenol (2), 3‐O‐acetyl‐20‐O‐angeloyl‐17‐hydroxyingenol (3), 17‐(acetyloxy)‐3‐O‐angelyl‐ingenol (4), 20‐O‐acetyl‐3‐O‐angeloyl‐17‐hydroxyingenol (5), 3‐O‐angelyl‐17‐(benzoyloxy)ingenol (6) and 20‐O‐acetyl‐3‐O‐angelyl‐17‐(benzoyloxy)ingenol (7). Compounds 1–4 were isolated for the first time, whereas 5–7 are known metabolites but detected for the first time in this plant. Biological investigations revealed that these compounds are tumor promoters.