Neuroprotective Properties of Compounds Extracted from Dianthus superbus L. against Glutamate-induced Cell Death in HT22 Cells

Background: Dianthus superbus L. has been used in Chinese herbal medicine as a diuretic and anti‑inflammatory agent. Objective: In this study, we isolated ten bioactive compounds from D. superbus and evaluated their neuroprotective activity against glutamate‑induced cell death in the hippocampal neuronal HT22 cells. Materials and Methods: New compound, (E)‑methyl‑4‑hydroxy‑4‑(8a‑methyl‑3‑oxodecahydronaphthalen‑4a‑yl) (1) and, nine known compounds, diosmetin‑7‑O (2’’,6’’‑di‑O‑α‑L‑rhamnopyranosyl)‑β‑D‑glucopyranoside (2), 4‑hydroxy‑3‑methoxy‑pentyl ester benzenepropanoic acid (3), vanillic acid (4), 4‑hydroxy‑benzeneacetic acid (5), 4‑methoxybenzeneacetic acid (6), (E)‑4‑methoxycinnamic acid (7), 3‑methoxy‑4‑hydroxyphenylethanol (8), hydroferulic acid (9), and methyl hydroferulate (10), were isolated by bioactivity‑guided separation. Structures of the isolated compounds were identified on the basis of 1H nuclear magnetic resonance (NMR), 13C NMR, and two‑dimensional NMR spectra, while their neuroprotective properties were evaluated by performing the 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide assay. Results: D. superbus extract had a neuroprotective effect and isolated 10 compounds. Among the compounds, compounds 5 and 6 effectively protected HT22 cells against glutamate toxicity. Conclusion: In conclusion, the extract of D. superbus and compounds isolated from it exhibited neuroprotective properties, suggesting therapeutic potential for applications in neurotoxic diseases.