Polyprenylated Tetraoxygenated Xanthones from the Roots of Hypericum monogynum and Their Neuroprotective Activities.

Ten new polyprenylated tetraoxygenated xanthones, monogxanthones A–J (1–10), together with eight known analogues (4b, 11–17) were identified from the roots of Hypericum monogynum. The structures of these new polyprenylated xanthones (1–10), a class of compounds rarely found in plants of the genus Hypericum, were elucidated by the interpretation of their HRESIMS, 1D and 2D NMR, and electronic circular dichroism data. Compounds 1 and 2 exhibited neuroprotective effects against corticosterone (Cort)-induced lesions of PC12 cells at concentrations of 6.25, 12.50, and 25.00 μM, with cell viability greater than 75%, as well as inhibitory effects on nitric oxide production in lipopolysaccharide-induced BV2 microglia cells, with IC50 values of 7.47 ± 0.65 and 9.60 ± 0.12 μM, respectively. Collectively, these results shed new light on the potential of polyprenylated xanthones from the genus Hypericum in the development of antidepression therapies.