Bioactive Segetane, Ingenane, and Jatrophane Diterpenes from Euphorbia taurinensis.

A novel segetane (1: ) and jatrophane diterpene (2: ), together with five known diterpenoids possessing segetane (3: ), jatrophane (4: ), and ingenane skeletons (5 - 7: ), were isolated from the methanol extract of Euphorbia taurinensis All. The structure elucidation of the compounds was performed by means of extensive spectroscopic analysis, including HRESIMS and 1D (1 H, J -modulated spin-echo carbon experiment) and 2D (HSQC, HMBC, COSY, NOESY) NMR experiments. The multidrug resistance reversing and cytotoxic effects of five diterpenes (1, 4:  - 7: ) were studied on the L5178 mouse lymphoma cell line using rhodamine 123 accumulation and the MTT cell viability assay. Segetane and jatrophane diterpenes had no cytotoxic activity on the sensitive parent and multidrug resistance cells, while ingenane diterpenes showed a cytotoxic effect on both cell lines. Ingenanes 6: and 7: and segetane 1: demonstrated the remarkable multidrug resistance modulating effect at 20 µM.