The motor and nonmotor symptoms of Parkinson's disease (PD) correlate with the formation and propagation of aberrant α-synuclein aggregation. This protein accumulation is a pathological hallmark of the disease. Our group recently showed that peucedanocoumarin III (PCIII) possesses the ability to disaggregate β sheet aggregate structures, including α-synuclein fibrils. This finding suggests that PCIII could be a therapeutic lead compound in PD treatment. However, the translational value of PCIII and its safety information have never been explored in relevant animal models of PD. Therefore, we first designed and validated a sequence of chemical reactions for the large scale organic synthesis of pure PCIII in a racemic mixture. The synthetic PCIII racemate facilitated clearance of repeated β sheet aggregate (β23), and prevented β23-induced cell toxicity to a similar extent to that of purified PCIII. Given these properties, the synthetic PCIII's neuroprotective function was assessed in 6-hydroxydopamine (6-OHDA)-induced PD mouse models. The PCIII treatment (1 mg/kg/day) in a 6-OHDA-induced PD mouse model markedly suppressed Lewy-like inclusions and prevented dopaminergic neuron loss. To evaluate the safety profiles of PCIII, high dose PCIII (10 mg/kg/day) was administered intraperitoneally to two-month-old mice. Following 7 days of PCIII treatment, PCIII distributed to various tissues, with substantial penetration into brains. The mice that were treated with high dose PCIII had no structural abnormalities in the major organs or neuroinflammation. In addition, high dose PCIII (10 mg/kg/day) in mice had no adverse impact on motor function. These findings suggest that PCIII has a relatively high therapeutic index. Given the favorable safety features of PCIII and neuroprotective function in the PD mouse model, it may become a promising disease-modifying therapy in PD to regulate pathogenic α-synuclein aggregation.
Keywords: Parkinson’s disease; distribution; dopaminergic cell loss; organic synthesis; peucedanocoumarin III; α-synuclein aggregation.