A new sesquiterpene-coumarin ether and a new abietane diterpene and their effects as inhibitors of P-glycoprotein

A new sesquiterpene-coumarin ether (5′β,9′α, 10′α)-7-0-(3α-methoxy-8′(12′)-drimen-11′-yl) -scopoletin, designated driportlandin (1) and a new abietane quinoid diterpene 16-hydroxyabieta-8,12-diene-11,14-dione, named portlanquinol (2) together with lupeol, nepehinol, wrightial, formonetin and davidigenin were isolated and characterized from the Me₂CO extract of whole dried plant of Euphorbia portlandica. The structures of the new compounds were elucidated from spectral data including 2D-NMR experiments of COSY, HMQC, HMBC and NOESY. When examined for their effects on the reversal of multidrug resistance (MDR) on mouse lymphoma cells, compound 1 proved to be more active than the positive control verapamil and compound 2 was found to be toxic. This is the First report on the isolation of a sesquiterpene-coumarin and a quinoid-type diterpenoid from Euphorbia.