Protective effects of baicalein against excess L-DOPA-induced dopamine quinone neurotoxicity

Abstract Objectives: Baicalein, a flavonoid derived from the root of Scutelaria baicalensis Georgi, possesses anti-oxidative properties including reactive oxygen species scavenging and lipid peroxidation inhibiting activities. The present study was undertaken to investigate the neuroprotective effect of baicalein against dopamine (DA) neurotoxicity induced by exposure to a synthetic DA precursor, L-3,4-dihydroxyphenylalanine (L-DOPA), in cultured dopaminergic CATH.a cells. Methods and results: Exposure to L-DOPA for 24 hours reduced the number of viable cells and enhanced protein-bound quinone (quinoprotein) formation in the cell. Both effects were prevented by simultaneous treatment with baicalein. In addition, baicalein prevented the formation of DA semiquinone radicals from DA in an in vitro cell-free system. Long-term baicalein treatment for 96 hours also protected against excess L-DOPA-induced cell death, and also increased glutathione (GSH) levels in CATH.a cells. Discussion: Our results indicate th...