Antioxidant and neuroprotective properties of scutellaria lateriflora

Abstract

American skullcap (Scutellaria lateriflora L., Lamiaceae) extracts have been used to treat several nervous disorders. There is still some uncertainty about the effective compounds, nevertheless, it is accepted that the flavonoids are important active constituents in skullcap. In the present study, we evaluated the antioxidant and neuroprotective potential of an ethanolic extract (SLE) prepared from leaves of S. lateriflora. The SLE main compounds were identified and quantified by HPLC-DAD. The flavones baicalein and baicalein-7-O-glucuronide were the major compounds found. The extract was very effective in scavenging the DPPH free radical (EC50, 83μg dwb/ml) and in reducing the lipid peroxidation of rabbit synaptossomes (EC50, 10μg dwb/ml), induced with ascorbate/Fe2+. We also assessed the potential antioxidant role of SLE in PC12 cells submitted to lipid peroxidation with ascorbate/Fe2+, in conditions that cause a significant increase of TBARS products (5x more). An SLE equivalent amount of 10μg dwb/ml significantly reduced (10%) the ascorbate/Fe2+ induced lipidic peroxidation, namely when PC12 cells were pre-incubated for 2 hours with the extract (35% reduction). The SLE extract by itself, even in a non-diluted concentration (100 mg dwb/ml), did not affect cell viability of PC12 cells under the experimental conditions used for lipid peroxidation. In a condition where ascorbate/Fe2+ induced lipidic peroxidation cause a significant loss of PC12 cell viability (up to 30%), this effect was attenuated by the use of SLE (10μg dwb/ml). When the PC12 cells where pre-incubated for 2 hours with the same concentration of SLE, cell death was significantly reduced (only 10% of the cells died). In conclusion, SLE could act as a strong antioxidant agent and have neuroprotective properties, which can account for the traditional use of this plant.