Abstract: Aim The objective of this study was to investigate solvent extracts of Sceletium tortuosum for their neuroprotective effect and further identify the constituents in the pharmacologically active solvent fractions. Methods Sceletium tortuosum material was extracted with petroleum ether and ethyl acetate respectively. The extracts were further subjected to silica-gel column chromatography to obtain six sub-fractions. The sub-factions were tested for neuroprotective effects based on their

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... evaluation in MPP+-injured N2a cells and L-glutamate-injured PC12 cells by MTT assay. The sub-fractions were further tested by ultraperformance liquid chromatography (UPLC) coupled to quadrupole-time-of-flight mass spectrometry (qTOF) with collision energy (MSE) to identify relevant constituents using MassFragment software in Masslynx4 software. Results The highly non-polar petroleum ether fraction and the polar ethyl acetate fraction showed potential in vitro neuroprotective activity. The UPLC-qTOF-MSE results of sub-fractions indicated the presence of dihydrojoubertiamine, mesembrenone, mesembrine, 2-oxomesembrine, Δ7-mesembrenone, N-demethyl-N-formylmesembrenone, dihydrobuphanamine acetate, sceletium A4, sceletenone, Δ7-N-demethyl-mesembrenone, 2-oxomesembranol, N-methyldihydrojoubertinamine and other unnamed components. Conclusion The polar and nonpolar extracts of Sceletium tortuosum exhibit neuroprotective effect in N2a cells or PC12 cells injured by MPP+ or L-glutamate respectively. Two sub-fractions each of the petroleum ether and ethyl acetate fractions were observed to have comparatively higher neuroprotective efficacy than other sub-fractions and the MS profile indicated the presence of dihydrojoubertiamine and an unidentified non-alkaloid in these two sub-fractions. While the presence of mesembrine, mesembrenone and other alkaloids were observed [...]