Tropane-Based Ibogaine Analog Rescues Folding-Deficient Serotonin and Dopamine Transporters

Missense mutations that give rise to protein misfolding are rare, but collectively, defective protein folding diseases are consequential. Folding deficiencies are amenable to pharmacological correction (pharmacochaperoning), but the underlying mechanisms remain enigmatic. Ibogaine and its active metabolite noribogaine correct folding defects in the dopamine transporter (DAT), but they rescue only a very limited number of folding-deficient DAT mutant proteins, which give rise to infantile Parkinsonism and dystonia. Herein, a series of analogs was generated by reconfiguring the complex ibogaine ring system and exploring the structural requirements for binding to wild-type transporters, as well as for rescuing two equivalent synthetic folding-deficient mutants, SERT-PG^601,602AA and DAT-PG^584,585AA. The most active tropane-based analog (9b) was also an effective pharmacochaperone in vivo in Drosophila harboring the DAT-PG^584,585AA mutation and rescued 6 out of 13 disease-associated human DAT mutant proteins in vitro. Hence, a novel lead pharmacochaperone has been identified that demonstrates medication development potential for patients harboring DAT mutations.