In the present work we described improvements in the 1-7 antiparasitic Morita-Baylis-Hillman Adducts synthesis and their antimitotic activity on sea urchin embryonic cells. The 2-[Hydroxy(2-nitrophenyl)methyl]acrylonitrile (1) and 2-[Hydroxy(4-bromophenyl) methyl]acrylonitrile (4) were the most effective compounds to block the progression to embryonic morula stage (EC(50) = 75.8 μM and 72.6 μM, respectively). Compounds 1 and 4 were also effective in blocking the first cell division but to a lesser extent. The 2-[Hydroxy(pyridin-4-yl)methyl]acrylonitrile (7) exhibited a strong inhibition of cell divisions and progression to the first cleavage and morula stage. Fluorescent dye extrusion assay suggests that these adducts are not ABC protein substrates, which confers an additional interest in these new class of potential anticancer drugs.