PRKN and Parkinson disease: Dopamine quinone and dopaquinone are representative endogenous quinones and have been well researched.(62,63) The quinones are possible elicitors of Parkinson’s disease by modifying neuronal proteins and successively affecting their functions.(63) For example, dopamine quinone covalently adducts with Parkin (E3 ubiquitin ligase) and then inhibits its ligase activity.(64) α-Synuclein is one target of the quinones, the adduction of which induces the aggregation of α-synuclein,(65) which is a possible major cause of Parkinson’s disease.