Neuroprotective effects of total flavonoid fraction of the Epimedium koreanum Nakai extract on dopaminergic neurons: In vivo and in vitro

Abstract

Flavonoids, the active components of Epimedii Genus, have been demonstrated to protect against osteoporosis, cardiovascular diseases and rheumatoid arthritis. The present study aimed to investigate the neuroprotective effects of total flavonoid (TF) fraction of Epimedium koreanum Nakai on dopaminergic neurons in the cellular and mice models of Parkinson's disease (PD). TF pretreatment could ameliorate the decrease of striatal dopamine (DA) content and the loss of tyrosine hydroxylase (TH)-immunoreactive neurons in the substantia nigra pars compacta (SNpc) induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). TF treatment could reverse the changes of Bcl-2 and Bax protein expressions in the striatum of PD mice. 1-Methyl-4-phenylpyridinium ion (MPP⁺) significantly decreased the cell viability and mitochondrial membrane potential in MES23.5 cells. These effects could be reversed by TF treatment. In addition, MPP⁺-induced changes of Bcl-2 and Bax mRNA and protein expressions were also reversed by TF pretreatment. These data demonstrated that TF of E. koreanum Nakai could protect against MPTP-induced dopaminergic neuronal death in mice and MPP⁺-induced neurotoxicity in dopaminergic MES23.5 cells. Anti-apoptosis might be involved in this process.

Keywords: Dopaminergic neuron; Epimedium koreanum Nakai; Neuroprotection; Parkinson's disease; Total flavonoids.