Fig. 1.

MPTP/MPMUS bioactivation pathways.

(A) Conversion of MPTP (I) to MPP⁺ (III) via MPDP⁺ (II) by sequential oxidation (‘O’); oxidation of MPTP is via MAOB and oxidation of MPDP⁺ is typically via the mitochondrial quinone pool.

(B) Analogous conversion by MAOB of MP-MUS (IV) to MD⁺-MUS (V). Again the dihydro species is converted to the pyridium, P⁺-MUS (VI). One of the chloroethyl groups of the mustard can ionize to give rise to either a 3-membered aziridinium (VII) or a 5-membered dihydrooxazolium (VIII) reactive ring system.