Safflower has long been used to treat cerebrovascular diseases in China. We previously reported that kaempferol derivatives of safflower can bind DJ-1, a protein associated with Parkinson's disease (PD), and flavonoid extract of safflower exhibited neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of PD. In this study, a standardized safflower flavonoid extract (SAFE) was isolated from safflower and mainly contained flavonoids. Two marker compounds of SAFE, kaempferol 3-O-rutinoside and anhydrosafflor yellow B, were proven to suppress microtubule destabilization and decreased cell area, respectively. We confirmed that SAFE in dripping pill form could improve behavioural performances in a 6-hydroxydopamine (6-OHDA)-induced rat model of PD, partially via the suppression of α-synuclein overexpression or aggregation, as well as the suppression of reactive astrogliosis. Using an MRI tracer-based method, we found that 6-OHDA could change extracellular space (ECS) diffusion parameters, including a decrease in tortuosity and the rate constant of clearance and an increase in the elimination half-life of the tracer in the 6-OHDA-lesioned substantia nigra. SAFE treatment could partially inhibit the changes in ECS diffusion parameters, which might provide some information about neuronal loss and astrocyte activation. Consequently, our results indicate that SAFE is a potential therapeutic herbal product for treatment of PD.Parkinson's disease (PD) is the second most common disorder of the central nervous system (CNS), and its incidence is increasing among people over the age of 60 years 1 . PD is pathologically characterized by the loss of dopaminergic neurons in the substantia nigra (SN) and the formation of cytoplasmic inclusion bodies; however, the aetiology of PD remains elusive. The clinical features of PD include muscular rigidity, resting tremor, bradykinesia, and postural instability. By the time patients are diagnosed with PD, approximately 80% of the striatal dopamine terminals have been lost 2 , and destruction of terminal fields may precede cell body loss in the SN 3 . In rats, the unilateral intracerebral injection of 6-hydroxydopamine (6-OHDA) results in a selective degeneration of dopaminergic neurons, and this is a widely used animal model of PD. 6-OHDA induces a neurodegenerative process in the nigrostriatal system through the inhibition of mitochondrial complex function, which can lead to the induction of oxidative stress, inflammation 4-6 , abnormal protein aggregation 7,8 , elevated iron levels 9 and ultimately cell death. Dopamine replacement therapy remains the first line strategy in PD treatment. However, its effectiveness cannot modify the progression of the neurodegenerative process. Additionally, dopamine replacement therapy is associated with side-effects that include fluctuations in motor response and dyskinesia 10 . Increasing attention 1
