Irritant and co-carcinogenic diterpene esters from the latex of Euphorbia cauducifolia L.

Abstract

Ten (1–10) irritant and mild co-carcinogenic diterpene esters were isolated from the latex of Euphorbia cauducifolia L. using bioassay-guided countercurrent distribution and other chromatographic techniques. The isolated compounds were characterized on the basis of spectroscopic results and mass measurements. As an outcome, the ingenane-type esters were established with the following structures: 3-O-angeloyl-17-O-palmatoylingenol (1), 3-O-palmatoyl-5-O-angeloylingenol (2), 5-O-angeloyl-17-O-palmatoylingenol (3), 3-O-angeloyl-5-O-palmatoylingenol (4), 17-O-(2Z,4E,6Z)-2,4,6-tetradecatrienoyl-20-O-palmatoylingenol (5), 5-O-angeloyl-17-O-benzoylingenol (6), 5-O-angeloyl-17,20-diacetoxyingenol (7), 3-O-angeloyl-17-O-benzoyl-20-acetoxyingenol (8), 3-acetoxy-5-O-angeloyl-17-O-benzoylingenol (9), and 5-O-angeloyl-3,17,20-triacetoxyingenol (10). Their biological screening revealed that they are moderate irritants, and low to moderate tumor promoters compared to TPA, but hardly showed any solitary carcinogenic activity. The isolated esters represent new compounds and were not reported before from any source.

Keywords:

• Euphorbia cauducifolia
• irritant
• tumor promoters
• diterpenes
• 17-hydroxyingenol esters