Cyparissins A and B, jatrophane diterpenes from Euphorbia cyparissias as Pgp inhibitors and cytotoxic agents against ovarian cancer cell lines

From the whole plant of Euphorbia cyparissias, two new diterpenes based on jatrophane skeleton, named cyparissins A and B (1 and 2) were isolated. Their chemical structures were established through a combination of nuclear magnetic resonance spectroscopy and mass spectrometric methods. The new cyparissins A and B were tested to evaluate their ability to inhibit P-glycoprotein-mediated multidrug resistance and their cytotoxic activity against A2780 human ovarian cancer cells, both WT and ADR. Compounds 1 and 2 showed moderate inhibitory effects on P-glycoprotein while showing a significant concentration-depending cytotoxic activity for both cancer cell lines. These isolated compounds are based on a new chemical structure that expands the knowledge base for this class of bioactive metabolites.