New 2,3‐Methylenedioxy‐naphthalene Derivatives With Neuroprotective Activity From the Roots of <i>Ephedra sinica</i> Stapf

Four new 2,3-methylenedioxy-naphthalene derivatives, named ephedplics A-D (1-4), were isolated from the roots of Ephedra sinica Stapf. The structures of compounds 1-4 were elucidated through comprehensive analyses of ultraviolet, infrared, high-resolution electrospray ionization mass spectrometry, and one-/two-dimensional nuclear magnetic resonance data. Ephedplics A-D represent newly identified natural derivatives featuring a 2,3-methylenedioxy-naphthalene scaffold. Furthermore, the isolated compounds were evaluated for their protective effects against corticosterone-induced injury in rat pheochromocytoma (PC-12) cells in vitro. Compounds 2-4 exhibited significant neuroprotective activity, potentially by mitigating the decline in mitochondrial membrane potential, reducing Ca²⁺ influx into PC-12 cells, and significantly increasing cell viability while decreasing the apoptosis rate. The results indicate that compounds 1-4 are novel and that compounds 2-4 may show neuroprotective effects.