Six novel steroids from culture of basidiomycete Polyporus ellisii

Investigation of the culture of basidiomycete Polyporus ellisii led to the isolation of a novel compound 3β,9α,15α-trihydroxy-(22E,24R)-10(5→4)-abeo-ergosta-6,8(14),22-trien-5-one (1) with a new 5/7/6/5 ring system of ergosterol skeleton. In addition, five new steroids, 5β,6β-epoxy-3β,7α,9α-trihydroxy-(22E,24R)-ergosta-8(14),22-dien-15-one (2), 5β,6β-epoxy-3β,7α-dihydroxy-(22E,24R)-ergosta-8(14),22-dien-15-one (3), 5α,6α-epoxy-3β,9α,15α-trihydroxy-(22E,24R)-ergosta-8(14),22-dien-7-one (4), 15α-acetoxy-(22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (5), 15β-methoxy-(22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (6), along with four known ergosterols (7–10), were obtained. All structures were elucidated based on 1D and 2D NMR spectral data. New compounds were evaluated for cytotoxicity against five human cancer cell lines, only compound 4 was found to exhibit a favorable cytotoxicity profile toward all tested tumor cell lines.