Neuroprotective potential of chrysin in Parkinson's disease: Molecular mechanisms and clinical implications

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, with current treatment being mainly symptomatic and often accompanied by serious side effects. In search of novel and safe therapeutic agents for PD, natural flavonoids have been shown to exert significant neuroprotective effects. Among them, chrysin (5,7-dihydroxyflavone) has been demonstrated to exhibit anti-oxidative effects to dopaminergic neurons mainly by increasing the expression of Nuclear Factor Erythroid 2 -related factor 2 (NRF2) which reduces intracellular nitric oxide (NO) levels and regulates anti-oxidant pathways. Moreover, chrysin activates Myocyte Enhancer factor 2D (MEF2D), a critical transcription factor involved in dopaminergic survival. It suppresses the MPP-induced upregulation of c-caspase and Bax as well as the downregulation of anti-apoptotic protein Bcl 2. Chrysin also enhances the production of neurotrophic factors, contributing to neuronal survival. Of interest, the combination of chrysin with protocatechuic acid (PCA) has been demonstrated to inhibit neuronal loss in PD animal models. Along with anti-inflammatory properties, chrysin has also been shown to increase dopamine levels in the striatum via monoamino-oxidase B (MAO-B) inhibition while it restores the behavioral deficits in PD animal models. In this review, we discuss the molecular mechanisms that underlie the possible neuroprotective effects of chrysin in PD pathogenesis along with its therapeutic potential.