Fig. 1. Illustration of similarity measures.
Using desipramine (target compound of some TCA screening assays) as the target compound, 2D similarity was calculated using MDL public keys and FCFP_6 to five different compounds, three of which (clomipramine, chlorpromazine, quetiapine) are three-ringed molecules and two of which (secobarbital, ibuprofen) have a single ring in their structures. Of the five test compounds, clomipramine (a TCA like desipramine) has the highest similarity to desipramine, while ibuprofen has the lowest similarity.