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

Abstract

A secondary metabolites investigation on <i>Biscogniauxia</i> sp. 71-10-1-1 was carried out, which led to the obtention of nine new diisoprenyl-cyclohexene/ane-type meroterpenoids (<b>1</b>-<b>9</b>) and two new isoprenylbenzoic acid-type meroterpeniods (<b>10</b>-<b>11</b>). The structures of these isolates were established on the basis of multispectroscopic analyses, ECD, and ¹³C chemical shifts calculations, and single-crystal X-ray diffraction. Among them, biscognin A (<b>1</b>) is the first diisoprenyl-cyclohexene-type meroterpenoid with a unique 2-isopropyl-6'-methyloctahydro-1'<i>H</i>-spiro[cyclopropane-1,2'-naphthalene] skeleton. Biscognienyne F (<b>5</b>) 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 <b>3</b> and <b>5</b> 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 (<b>1</b>-<b>5</b>) are proposed.