Novel lignan-based compounds via click chemistry: paulownin isolation, structural modifications and cytotoxic activity evaluations.

Paulownin, a natural compound obtained from the tree Tecoma stans var. stans, was chemically modified by alkylation of its hydroxyl position. Thirteen novel lignans derivatives synthesized via a copper-catalyzed cycloaddition (CuAAC), known as click reaction, using different organic azides and lignan terminal alkyne. Characterization by mass spectrometry, NMR (1H and 13C) and infrared spectroscopy. These novel molecules were submitted to biological tests, using the MTT colorimetric technique aiming at the verification of their antitumor properties with six different cells lines. Biological evaluation was satisfactory and one of compounds showed selectivity index ten times higher than podophyllotoxin.