Properties of the melanin binding of p-bromo-methylamphetamine (V-111)

The aim of the present study was to obtain detailed information on the binding properties of p-bromomethylamphetamine (V-111) to melanins under in vitro and in vivo conditions. The results obtained by the methods of both equilibrium and dynamic dialysis revealed that the binding of V-111 to bovine eye melanin was reversible, at least for the part of the binding sites, whereas the dissociation of V-111-melanin adduct was slow. The binding capacity of two different classes of binding sites of bovine eye melanin and dissociation constants of the drug-melanin complexes have been determined. The in vivo melanin binding of V-111-1-14C was studied by the method of whole body autoradiography. Extensive accumulation and retention was observed in the eyes of the pigmented mice while in the albino animal uptake was low in the corresponding tissues. In conclusion, V-111 may most probably be accumulated and retained for long periods in the pigmented cells of intact animals. Our data also imply that melanin in the pigmented cells serves as a depot, which gradually releases p-bromo-methylamphetamine resulting in a prolonged local effect of this compound.