Cytotoxic lignans from Larrea tridentata

Six lignans, including the cyclolignan 3,4′-dihydroxy-3′,4-dimethoxy-6,7′-cyclolignan, were isolated from Larrea tridentata. All of the compounds were assessed for their growth inhibitory activity against human breast cancer, human colon cancer and human melanoma cell lines (IC50 = 5-60 μM). Linear butane-type lignans were most potent.