Nivalones C F, four new meroterpenoids from Rhododendron nivale

Four new meroterpenoids, namely nivalones CF (1–4), along with a known meroterpenoid, cannabiorcicyclolic acid (5), were isolated from the branches and leaves of Rhododendron nivale. The chemical structures of compounds 1–4 were elucidated through comprehensive spectroscopic analyses, including NMR, UV–Vis, IR, ECD spectroscopy, as well as HR-ESI-MS. The isolated compounds were evaluated for their anti-inflammatory and neuroprotective properties. The inhibitory activity of compound 5 against lipopolysaccharide (LPS)-induced nitric oxide (NO) production was initially demonstrated, showcasing an IC50 value of 21.1 μM. Additionally, both compounds 2 and 5 displayed a notable effect on the viability of H2O2-damaged SH-SY5Y cells, indicating their significant neuroprotection effects.