New natural products, designated pochoniolides A and B, were isolated from the cultured broth of fungal strain FM 7537 using a physicochemical screening methodology. Strain FKI-7537 was isolated from a soil sample collected at Niijima, Tokyo, Japan and identified as Pochonia chlamydosporia var. spinulospora by morphological characteristics and DNA sequence analysis. The chemical structures of pochoniolides A and B were elucidated by NMR and mass spectra and found to be new compounds consisting of a muconolactone moiety connected with a chromone unit. Pochoniolides A and B were identified as racemate mixtures using data on optical rotation and circular dichroism spectra. Furthermore, enantiomers of pochoniolide B, pochoniolides B1 and B2, were separated using a chiral HPLC column. Pochoniolides A and B showed hydroxyl radical-scavenging and singlet oxygen-quenching activities. (C) 2018, The Society for Biotechnology, Japan. All rights reserved.