Neuroprotective Secondary Metabolite Produced by an Endophytic Fungus, Neosartorya fischeriJS0553, Isolated from Glehnia littoralis

Roots of Glehnia littoralishave been used to heal stroke as a traditional medicine. Even though many studies on this plant have been conducted, the secondary metabolites produced by its endophytes and their bioactivities have not been investigated thus far. Therefore, a new meroditerpenoid named sartorypyrone E (1) and eight known compounds (2–9) were isolated from extracts of cultured Neosartorya fischeriJS0553, an endophyte of G. littoralis. The isolated metabolites were identified using spectroscopic methods and chemical reaction, based on a comparison to literature data. Relative and absolute stereochemistries of compound 1were also elucidated. To identify the protective effects of isolated compounds (1–9) in HT22 cells against glutamate-induced cytotoxicity, we assessed inhibition of cell death, intracellular reactive oxygen species (ROS) accumulation, and calcium ion (Ca2+) influx. Among the isolates, compound 8, identified as fischerin, showed significant neuroprotective activity on glutamate-mediated HT22 cell death through inhibition of ROS, Ca2+influx, and phosphorylation of mitogen-activated protein kinase, including c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38. The results suggested that the metabolites produced by the endophyte N. fischeriJS0553 might be related to the neuroprotective activity of its host plant, G. littoralis.