Abstract Several analogs of gigantol (1) were synthesized to evaluate their effect on the complexes Ca 2+–calmodulin (CaM) and Ca 2+–CaM–CaM sensitive phosphodiesterase 1 (PDE1). The compounds belong to four structural groups including, 1, 2-diphenylethanes (2– 11), diphenylmethanes (13–15), 1, 3-diphenylpropenones (16–18), and 1, 3- diphenylpropanes (20–22). In vitro enzymatic studies showed that all compounds except ...