Antioxidant and Neuroprotective Activity of the Aerial Parts of Seven Eragrostis Species and Bioactive Compounds from E. japonica

The main purpose of this study was to evaluate the antioxidant and neuroprotective activities in the aerial parts of seven Eragrostis species (Poaceae) and to find antioxidant or neuroprotective compounds from the most active species. The total phenolic content (TPC), total flavonoid content (TFC), 1,1-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH RSA), total antioxidant capacity (TAC), and neuroprotective activity against amyloid beta peptide induced toxicity in PC12 cells were measured in the methanol extracts of the aerial parts of E. ferruginea, E. cilianensis, E. minor, E. multicaulis, E. pilosa, E. japonica, and E. curvula collected from June to August 2013. All species showed antioxidant or neuroprotective activities and, among them, E. japonica was the most active species to isolate antioxidant or neuroprotective compounds, because it was found to show both the highest TPC (10.63 ± 0.31 mg/g) and TFC (2.83 ± 0.06 mg/g) values, as well as TAC (11.34 ± 0.80 mg/g) and DPPH RSA (47.07 ± 2.81 µg/mL), with the second-highest neuroprotective value (23.0 µg/mL). Three known compounds were isolated from E. japonica by the bioassay guided approach and these were identified as isoorientin, isovitexin, and caffeic acid that have antioxidant and neuroprotective activities.