DISPLACEMENT ACTIVITY OF SOME NATURAL CULARINE ALKALOIDS AT STRIATAL H-3 SCH 23390 AND H-3 RACLOPRIDE BINDING-SITES

Five natural cularines isolated from the aerial parts of Sarcocapnos crassifolia (Fumariaceae) and a cularioid isolated from the bark of Guatteria ouregou (Annonaceae) were tested for their ability to displace H-3-SCH 23 390 and H-3-raclopride from their striatal binding sites. Celtisine, breoganine and cularidine were able to inhibit the binding at D-1 and D-2 dopaminergic sites at nanomolar concentrations. Other alkaloids were active at micromolar concentrations. These data suggest that the presence of an oxepine system in the isoquinoline skeleton could lead to compounds which would be very active and possibly selective at dopaminergic receptor sites.