Euphoportlandols A and B, tetracylic diterpene polyesters from Euphorbia portlandica and their anti-MDR effects in cancer cells

Abstract

Two new tetracyclic diterpene polyesters, euphoportlandols A (1) and B (2), have been isolated along with 12 known tetracyclic triterpenes from an acetone extract of Euphorbia portlandica. Their structures were established as 5 alpha, 11 alpha,-14 alpha, 17-tetraacetoxy-3 beta-benzoyloxy-6 beta, 15 beta-dihydroxy-9-oxoseget-8(12)-ene (1) and 5 alpha,11 alpha,14 alpha,17-tetraacetoxy-3 beta-benzoyloxy- 6 beta, 15 beta- dihydroxy-9-oxosegetane (2), respectively, by spectroscopic data interpretation. Compounds 1 and 2 were evaluated for their ability to inhibit multidrug resistance in cancer cells. Both compounds were found to be inhibitors of P-glycoprotein activity.