Having demonstrated the strict target selectivity of N-PPG for PRODH by showing its inability to inhibit other mitochondrial or cytosolic flavoproteins (Scott et al. 2019), we were encouraged to look into its brain penetrating potential since another propargylic (N-PPG-like) analog, rasagiline, a clinically approved selective and irreversible inhibitor of the FAD-containing monoamine oxidase (MAO-B), readily crosses the blood–brain barrier and is used to treat Parkinson’s disease (Binda et al. 2005). Here, MAOB is linked to Parkinson disease.