Bioactive secondary metabolites produced by an endophytic fungus Gaeumannomyces sp. JS0464 from a maritime halophyte Phragmites communis.

ABSTRACT

Endophytes, important plant-associated mycobionts, have attracted a great deal of attention because of their bioactive secondary metabolites. Even though halophytes have been reported to overcome salt stress via associations with their endophytes, few studies have investigated the metabolites produced by the endophytes from halophytes. In this study, a dark septate endophytic fungal strain (JS0464), identified as Gaeumannomyces sp. by ITS sequencing, was isolated from the rhizome of a halophyte, Phragmites communis, in Suncheon bay, South Korea. This strain was cultured on a large scale and extracted with ethyl acetate. Chemical investigations of extracts of JS0464 led to the isolation of two glycosylated dialkylresorcinol derivatives (1-2), an anthraquinone derivative (3) and eight known compounds (4-11), which were identified by spectroscopic analyses incorporating one-dimensional/2D NMR and MS. Nine compounds showed significant nitric oxide reduction activity in lipopolysaccharide-stimulated microglia BV-2 cells, seven of which did not impair cell viability. The results suggest that endophytes from the halophytes could be potential resources for bioactive natural products.