Synthesis and cytotoxic activity evaluation of dihydrocucurbitacin B and cucurbitacin B derivatives.
Lang KL, Silva IT, Zimmermann LA, Machado VR, Teixeira MR, Lapuh MI, Galetti MA, Palermo JA, Cabrera GM, Bernardes LS, Simões CM, Schenkel EP, Caro MS, Durán FJ.
Two cucurbitacins, dihydrocucurbitacin B (1) and cucurbitacin B (2), which can be obtained in large amounts from the roots of Wilbrandia ebracteata and from the fruits of Luffa operculata, respectively, were used as starting materials for the preparation of a library of 29 semi-synthetic derivatives. The structural changes that were performed include the removal, modification or permutation of functional groups in rings A and B as well as in the side chain. All new semisynthetic compounds, as well as 1 and 2, were tested in vitro for their cytotoxic effects on non-small-cell lung cancer cells (A549 cells). Some of these compound displayed potent to moderate activity against A549 tumor cells, especially those cucurbitacin B derivatives which were modified at ring A.