Megastigmane glycosides from the leaves of <i>Nicotiana tabacum</i> and their neuroprotective activities

A total of 12 megastigmane glycosides (<b>1 </b>-<b> 12</b>), including four undescribed ones, were extracted from the leaf tissues of <i>Nicotiana tabacum</i>. The molecular frameworks of all isolates could be indicated by 1D and 2D-NMR analysis and mass spectrometry along with comparison with those previously reported. Absolute configuration from four new metabolites (<b>1 </b>-<b> 4</b>) was established through ECD and empirical rules of ¹³C-NMR chemical shift. Additionally, a hydrogen peroxide-induced SH-SY5Y cell model was used to assess the isolates' <i>in vitro</i> neuroprotective activity, and the bioassay results demonstrated compounds <b>2</b>, <b>3</b>, <b>6</b>, and <b>7</b> displayed moderate protective effects against H₂O₂-induced neurotoxicity at 10 μM in comparison to the positive control, edaravone.