Safrole from sassafras oil (Ocotea pretiosa Mez., Lauraceae), is an abundant natural product showing interesting functionality and chemical structure. Starting from safrole, nine derivatives were prepared and assessed for antiproliferative effect using different human cell lines. The in vitro growth inhibition assay was based on the sulphorhodamine dye to quantify cell viability. Some safrole derivatives, (2E)-3-(3',4'-methylenedioxi)phenyl acrylaldehyde (3) and 4-allyl-5-nitrobenzene-1,2-diol (4) presented better antiproliferative effect than the parent compound on two breast cancer cell lines (MCF-7 and MDA-MB-231) and one human colorectal cancer cell line (DLD-1) with IC(50) values of 55.0 +/- 7.11 mu M, 37.5 +/- 2.65 mu M and 44.0 +/- 6.92 mu M, respectively, without toxicity towards dermal human fibroblast (DHF cells).