Fungi in forest litter are diverse as decomposers but natural products from these fungi are rarely investigated, especially for their antimicrobial activities against crop diseases. In this study, fungal isolate SGSF723 with antimicrobial activities was cultured. A multi-gene phylogenetic analysis showed SGSF723 was an undescribed species in the family Phaeosphaeriaceae. By bio-guided assay, three new compounds (Phaeosphaeridiols A-C) and two known compounds were purified from the ethyl acetate extract. The structures of Phaeosphaeridiols A-C were elucidated as 2-(2'-butenyl)-5 (3″-pentene)-1,3-benzenediol (1), 2-(2'-butenyl)-5-(3″S,4″S-pentane diol)-1,3-benzenediol (2), and 3-(4'-(2″-butenyl)-3',5'-benzenediol phenol)-2-acrylic acid (3) by 2D NMR, HRESIMS, and Mosher's method. Phaeosphaeridiols A-C exhibited moderate or weak antimicrobial activities against plant pathogens by 96-well plate and spore germination assays.
Keywords: Pleosporales; antimicrobial compounds; forest litter; phylogeny.