Search

An undescribed isocoumarin derivative, named (±)-isothielavic acid (1), was isolated from the metabolites of endophytic fungus Thermothielavioides terrestris YB4 together with two known compounds 4(S)-thielavic acid (2) and thymine (3). The structure of (±)-isothielavic acid (1) was elucidated by comprehensive analysis of NMR spectroscopy and HRESIMS data as well as single-crystal X-ray diffraction experiment. Bioassay results indicated the weak antibacterial activity of compound 1 in vitro. [Display omitted] • A new isocoumarin derivative, given the trivial name (±)-isothielavic acid (1), was isolated from Thermothielavioides terrestris. • The isolated compound could be used as a scaffold for the synthesis of much more complex heterocyclic scaffolds. • Compound 1 exhibited antibacterial activity against Bacillus subtilis , Pseudomonas aeruginosa and Escherichia coli. [ABSTRACT FROM AUTHOR]