Archromones A–F, unusual polycyclic dearomatic geranylquinol derivatives from the roots of Arnebia euchroma

Abstract

Eight new geranylquinol derivatives (1–8) were purified from the roots of Arnebia euchroma. Compounds 1–6 possess an unprecedented dearomatic benzocogeijerene skeleton with a rare trans-fused hydronaphthalene moiety. Their structures and absolute configurations were elucidated by HRESIMS, NMR, ECD, and X-ray diffraction. A convenient strategy for rapid determination of the relative configuration of H-1/H-7/Me-16 and the absolute configuration at C-1 for 1–6 was summarized. Compound 2 exhibited cytotoxicity against all the tested cell lines, namely PC9, BGC823, HCT116, HepG2, HeLa, and U87-MG, with IC₅₀ values ranging from 13.7 to 29.3 μM.