Strophasterols E and F: Rearranged ergostane-type sterols from Pleurotus eryngii

[Display omitted] •Strophasterols E and F (1, 2) were isolated from Pleurotus eryngii.•Their absolute structures were determined by X-ray crystallography.•Four new ergostane-type steroids (3–6) were also isolated.•Compound 5 exhibited inhibitory effects of NO production in conjunction with low cytotoxicity. Strophasterols E (1) and F (2) were isolated from the fruiting bodies of Pleurotus eryngii, together with four new ergostane-type sterols (3–6). Single-crystal X-ray diffraction analysis performed on the tris-p-bromobenzoate derivatives of compounds 1 and 2 allowed these two compounds to be identified as the structurally rare (22S,23R)- and (22S,23S)-5α,6α-epoxy-3β,7β,23-trihydroxy-15(14 → 22)-abeo-ergost-8-en-14-one, respectively. The inhibitory effects on nitric oxide production of the six new steroids thus isolated from the fruiting bodies of P. eryngii were also evaluated.