Four Tremulanes and Two Pyroglutamate‐Containing Dipeptides from the Mangrove Endophytic Fungus Phaeosphaeriopsis sp. P11

Four new tremulane sesquiterpenes, named phaeosphaerienols A–D (1–4), and two new pyroglutamate‐containing dipeptides, named phaeosphaeratides A–B (5–6), were isolated from the mangrove endophytic fungus Phaeosphaeriopsis sp. P11, together with a new 2‐furancarboxylic acid derivative (7). Structurally, pheaosphaerienols A–C (1–3) are rare tremulanes containing a 1,10‐epoxide moiety. The structures of these compounds were established by extensive NMR spectroscopic data, single‐crystal X‐ray diffraction analysis, and Marfey’s derivatization method. All the isolates were evaluated for their cytotoxic, antibacterial, and DPPH free radical scavenging effects. However, none of the compounds exhibited obvious activities.