Neuroprotective Effects of Chalcones from Myracrodruon urundeuva on 6-Hydroxydopamine-Induced Cytotoxicity in Rat Mesencephalic Cells

Abstract

In the present work, we showed that a chalcone-enriched fraction (CEF) isolated from the stem bark of a Brazilian medicinal plant, Myracrodruon urundeuva, presents neuroprotective actions on 6-hydroxydopamine (6-OHDA)-induced neuronal cell death, in rat mesencephalic cells. In the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium] assay, which is an index of cell viability, CEF (1-100 microg/ml) reversed in a concentration-dependent manner the 6-OHDA-induced cell death. While cells exposed to 6-OHDA (40 microM) showed an increased concentration of thiobarbituric acid reactive substances (TBARS), the pretreatment with CEF (10-100 microg/ml) significantly decreased the 6-OHDA-induced TBARS formation, indicative of a neuroprotection against lipoperoxidation. Furthermore, the drastic increase of nitrite levels induced by 6-OHDA, indicative of nitric oxide formation and free radicals production, was prevented by CEF. Double staining with acridine orange/ethidium bromide showed that cultures exposed to 6-OHDA (40 and 200 microM) presented an increase of apoptotic and necrotic cell numbers in a concentration-dependent manner. CEF (100 microg/ml) protected cells from apoptosis and necrosis and increased number of cells presenting a normal morphology. The immunohistochemical analysis for tyrosine hydroxylase (TH) positive neurons indicated that 6-OHDA (40 and 200 microM) caused a concentration-dependent loss of TH+ and TH- neurons. CEF protected both cells types from 6-OHDA-induced cell death. All together, our results demonstrated neuroprotective effects of chalcones, which are able to reduce oxidative stress and apoptotic injury caused by 6-OHDA. Our findings suggest that chalcones could provide benefits, along with other therapies, in neurodegenerative injuries, such as Parkinson's disease.