Two new lignans from the resin of <i>Bursera microphylla</i> A. gray and their cytotoxic activity

<p>Two new lignans, namely 7-O-podophyllotoxinyl butyrate (<b>1</b>) and dihydroclusin 9-acetate (<b>2</b>), were isolated from the dichloromethane fraction of a methanol extract of <i>Bursera microphylla</i> (Burseraceae), along with eight known lignans (<b>3</b>–<b>10</b>). Their structures were determined by means of comprehensive spectroscopic analysis. Lignans <b>2</b>–<b>6</b> were tested for their anti-proliferative activity on the cancer cell lines LS180, A549 and HeLa, and on a non-cancer cell line, ARPE-19. Only compounds <b>4</b> and <b>5</b> showed an interesting activity on HeLa cells.</p