Molecular Networking-Aided Discovery of Salviarobones A and B, Terpenoids with Unique Carbon Skeletons from Salvia roborowskii

Two unusual terpenoids, salviarobones A and B (1 and 2), were isolated from Salvia roborowskii guided by feature-based molecular networking. Salviarobone A (1) was a novel C₂₃-terpenoid featuring a unique 6/6/6/5/6 fused pentacyclic ring skeleton. Salviarobone B (2) was a norditerpenoid with an unprecedented 6/6/5 fused tricyclic ring system. Their structures and absolute configurations were unambiguously established by HRESIMS, NMR spectroscopic data, DP4+ analyses, ECD calculations, and single-crystal X-ray diffraction. It is also worth noting that 1 exhibits neuroprotective effect based on H₂O₂-induced oxidative damage in PC12 cells.