Objective: The aim of this study was to investigate the antioxidative and neuroprotective activities of various extracts from the fruit hull of mangosteen (Garcinia mangostana Linn., GM). Materials and Methods: Four extracts: water, 50% ethanol, 95% ethanol and ethyl acetate, were used. The antioxidative activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl free-radical scavenging assay at extract concentrations of 1, 10, 50 and 100 µg/ml. Based on the free radical scavenging activity of the extracts, two (water and 50% ethanol) were selected for their protective activity in NG108-15 neuroblastoma cells against H₂O₂-induced oxidative stress and for cell viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Results: All extracts exhibited antioxidative activity. The water and 50% ethanol extracts showed high free-radical scavenging activity with IC₅₀ values of 34.98 ± 2.24 and 30.76 ± 1.66 µg/ml, respectively. Both water and 50% ethanol extracts exhibited neuroprotective activity on NG108-15 cells. The highest activity was observed at the concentration of 50 µg/ml for both the water and 50% ethanol extracts. For cytotoxicity test, none of the extracts was toxic to the cells except at the high concentration of 100 µg/ml. Conclusions: These results suggest that the water and 50% ethanol extracts from the fruit hull of GM may be potent neuroprotectants.

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BackgroundPhikud Navakot (PN), a combination of nine herbs, has been used traditionally in Thai medicinal formulas to relieve circulatory disorder. The present study aimed to compare the synergistic antioxidant efficacy and toxicity of the hydroethanolic and water extracts of PN at cellular level.MethodsPN and its nine herbs were extracted with either 50% ethanol or water. All extracts were tested for in vitro antioxidant potential using standard antioxidant assays. Evaluation of cytotoxicity, genotoxicity, and intracellular reactive oxygen species were performed using human endothelial ECV304 cells.ResultsAntioxidant assays in cell-free systems showed that the hydroethanolic extract of PN scavenged superoxide, hydroxyl, nitric oxide radicals, and hydrogen peroxide more effectively than its water extract. Combination indices were calculated to show that the ingredients of the hydroethanolic extract acted synergistically to exhibit antioxidant activities against all tested radicals, whereas, in the case of water extract, this effect was observed only against 2,2-diphenyl-1-picrylhydrazyl, superoxide, and hydroxyl radicals. A cell-based assay also revealed that the hydroethanolic extract concentration-dependently attenuated hydrogen peroxide-induced stress more effectively than the water extract. At the antioxidant and cytotoxic concentrations of both extracts, no genotoxicity was found.ConclusionOur findings demonstrate that the synergistic antioxidant action of PN ameliorates endothelial stress, which may provide some clues for understanding the traditional use of PN for the treatment of circulatory disorder. Additionally, the selection of a suitable solvent for the extraction of PN herbal combination is essential for maximal efficacy and safety.