The invention relates to a method of treating or preventing Parkinson's disease in a subject comprising administering a compound of Formula I wherein, R1 is —NHC(O) C3-6 cycloalkyl and R2 is hydrogen; or R1 and R2 along with the carbon atoms to which they are attached form a six membered aromatic ring, wherein the ring is substituted with one or more groups selected from hydrogen, halogen and C1-6 alkyl; R3 and R4 are independently selected from group comprising hydrogen, halogen, C1-3 alkyl, OC1-3 alkyl, NO2, SC1-3 alkyl, C1-3 haloalkyl, OC1-3 haloalkyl, and SC1-3 haloalkyl; or a pharmaceutically acceptable salt thereof.