Objective: To evaluate the effects of the hydroalcoholic extract of red propolis (HERP) and one of its major compounds, formononetin (FN), against the motor symptoms and neurodegenerative process induced by 6-hydroxydopamine (6-OHDA) in rats.

Background: The hallmarks of Parkinson’s disease (PD) physiopathology include oxidative stress, neuroinflammation and apoptosis. The HERP has received great attention as an antioxidant and anti-inflammatory bee product [1]. Also, the isoflavone FORM was protective after traumatic brain injury in rats with antiapoptotic and anti-inflammatory properties [2].

Method: The chemical composition of the HERP was assessed by high performance liquid chromatography. Adult male Wistar rats received unilateral intraestriatal injection of ascorbate saline or 6-OHDA. The rodents (n = 8/group) were treated orally with vehicle or HERP (10 and 50 m/kg) daily for 21 days thereafter. FN (10 and 20 mg/kg) or saline were given i.p. after surgery, for the same period. The open field test was performed at day 21 in order to evaluate the motor performance (mean of crossings and rearing in 5 min) and the euthanasia was carried out at day 28. The striatum and substantia nigra pars compacta (SNc) of rat brains were stained by immunohistochemistry for tyrosine-hydroxylase (TH). Comparisons between treatments in each experiment were made through one way ANOVA followed by Tukey post-hoc (p <0.05).

Results: They were found formononetin (6.3 mg/g), liquiritigenin (10 mg/g), daidzein (3.1 mg/g) and biochanin A (7.2 mg/g) in the HERP. The HERP 10 m/kg (but not 50 mg/kg) and FN 20 mg/kg (but not 10 mg/kg) counteracted the 6-OHDA-induced impairment on crossings and rearing. In the SNc, the mean number of TH positive neurons was reduced after lesion and the values were increased when HERP 10 and FN 20 were given. Also, the dopaminergic innervation was preserved by HERP 10 and FN 20.

Conclusion: Both HERP 10 mg/kg and FN 20 mg/kg protected from motor deficits and dopaminergic neuron loss induced by 6-OHDA. They can be, therefore, promising agents to be considered in the treatment of neurodegenerative-related movement disorders.

References: [1] Freires et al. 2016. A pharmacological perspective on the use of Brazilian Red Propolis and its isolated compounds against human diseases. Eur J Med Chem 2016; 110:267-279; [2] Li et al., 2018. Neuroprotective effect of formononetin against TBI in rats via suppressing inflammatory reaction in cortical neurons. Biomed Pharmacother. 2018; 106:349-354.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neuroprotective-actions-of-red-propolis-extract-and-formononetin-in-a-rat-model-of-parkinsons-disease/