We have designed more potent inhibitors from the previously reported LF 05-0038, a 6-isoquinolinol based inhibitor of 2,3-oxidosqualene cyclase (IC50: 1.1 microM). Replacement of the 3-OH group by various 3-substituted amino groups, and modification of the alkyl chain borne by the endocyclic nitrogen led to inhibitors with IC50 in the range of 0.15 to 1 microM. In a second step, opening of the bicyclic ring system afforded the corresponding aminoalkylpiperidines which were slightly more potent. Finally, introduction of suitable aromatic containing moieties on the piperidine nitrogen yielded very potent inhibitors such as 20x (IC50 = 18 nM) easy to synthesize and achiral. The recent availability of the crystal structure of squalene-hopene cyclase allowed us to construct a three-dimensional (3D) model of the related 2,3-oxidosqualene cyclase (OSC) which was tentatively used to describe the possible mode of binding of our compounds and which can be useful for designing new inhibitors.