Diisoprenyl-cyclohexene/ane-Type Meroterpenoids from Biscogniauxia sp. and Their Anti-inflammatory Activities

A secondary metabolites investigation on Biscogniauxia sp. 71-10-1-1 was carried out, which led to the obtention of nine new diisoprenyl-cyclohexene/ane-type meroterpenoids ( 1 – 9 ) and two new isoprenylbenzoic acid-type meroterpeniods ( 10 – 11 ). The structures of these isolates were established on the basis of multispectroscopic analyses, ECD, and 13 C chemical shifts calculations, and single-crystal X-ray diffraction. Among them, biscognin A ( 1 ) is the first diisoprenyl-cyclohexene-type meroterpenoid with a unique 2-isopropyl-6′-methyloctahydro-1′ H -spiro[cyclopropane-1,2′-naphthalene] skeleton. Biscognienyne F ( 5 ) is the first diisoprenyl-cyclohexene-type meroterpenoid with a cyclic carbonate. The anti-inflammatory assays of the majority of compounds were evaluated, which exhibited that compounds 3 and 5 can obviously inhibit pro-inflammatory cytokines TNF-α and IL-6 productions. This is the first report for diisoprenyl-cyclohexene-type meroterpenoids with anti-inflammatory activity. Moreover, the possible biogenetic pathways of the majority of compounds ( 1 – 5 ) are proposed.