In this study, researchers from different universities in South Korea demonstrated how silibinin, a flavonoid found in milk thistle, can be used for Parkinson's disease therapy. The results of their study were published in the Journal of Medicinal Food.
Both Parkinson's disease and Alzheimer's disease exhibit common features of neurodegenerative diseases and are caused by numerous factors.
One common feature of both diseases is neurotoxic inflammation caused by activated microglia. The regulation of microglial activation is a potential mechanism for preserving neurons in the brains of patients with Alzheimer's or Parkinson's.
In a previous study, researchers reported that the upregulation of prothrombin kringle-2 (pKr-2), a prothrombin domain that is cleaved and generated by active thrombin, can induce neurotoxic microglial activation, which leads to nigral dopaminergic neuronal death.
To determine the effect of silibinin, they treated mice substantia nigra with the flavonoid and pKr-2.
They found that silibinin can suppress the production of inducible nitric oxide synthase (iNOS) and neurotoxic inflammatory cytokines like interleukin-1B and tumor necrosis factor-a (TNF-a). This inhibition happens via the downregulation of the extracellular signal-regulated kinase signaling pathway.
The researchers also performed immunohistochemical staining, measured dopamine and metabolite levels, and conducted open-field behavioral tests to evaluate silibinin activity.
They reported that silibinin treatment protected the nigrostriatal dopaminergic system from pKr-2-triggered neurotoxic inflammation in vivo.
Based on these results, the researchers concluded that silibinin is a beneficial natural compound with anti-inflammatory effects against pKr-2-triggered neurotoxicity. They believe that it can be used to protect the nigrostriatal dopaminergic pathway and treat Parkinson's disease.
Leem E, Oh YS, Shin W-H, Jin BK, Jeong JY, Shin M, Kim DW, Jang JH, Kim HJ, Ha CM, Jung UJ, Moon GJ, Kim SR. EFFECTS OF SILIBININ AGAINST PROTHROMBIN KRINGLE-2-INDUCED NEUROTOXICITY IN THE NIGROSTRIATAL DOPAMINERGIC SYSTEM IN VIVO. Journal of Medicinal Food. 15 March 2019;22(3):277–285. DOI: 10.1089/jmf.2018.4266