Phomopsols A and B from the Mangrove Endophytic Fungus <i>Phomopsis</i> sp. xy21: Structures, Neuroprotective Effects, and Biogenetic Relationships

Abstract

A polyketide-derived alkaloid featuring a unique 3,4-dihydro-2<i>H</i>-indeno[1,2-<i>b</i>]pyridine 1-oxide motif, named phomopsol A (<b>1</b>), and a highly oxidized polyketide containing a new 3,5-dihydro-2<i>H</i>-2,5-methanobenzo[<i>e</i>][1,4]dioxepine moiety, named phomopsol B (<b>2</b>), were isolated from the Thai mangrove endophytic fungus <i>Phomopsis</i> sp. xy21, together with the related biosynthetic polyketide <b>3</b>. The structures of <b>1</b>-<b>3</b> were unambiguously established by single-crystal X-ray diffraction analysis (Cu Kα), and their neuroprotective effects in PC12 cells were evaluated. The biosynthetic origins of <b>1</b>-<b>3</b> are proposed.