One new ergostane-type steroid and three new phthalide derivatives from cultures of the basidiomycete Albatrellus confluens

One new ergostane-type steroid, (12β,15β,22R,23S,24S)-22,25-epoxy-12,15,23-trihydroxyergost-4,6,8(14)-trien-3-one (1), three new phthalide derivatives, 5-(2′,3′-epoxy-3′,3′-dimethylpropoxy)-7-methoxy-6-methylphthalide (2), (2′)-(Z)-5-(3′-hydroxymethyl-3′-methylallyloxy)-7-methoxy-6-methylphthalide (3), and 5-(3′,3′-dimethylallyloxy)-7-hydroxy-6-methylphthalide (4), along with one known phthalide derivative, 5-(3′,3′-dimethylallyloxy)-7-methoxy-6-methylphthalide (5), were isolated from cultures of the basidiomycete Albatrellus confluens. The structures of the new compounds were established on the basis of extensive spectroscopic data (IR, MS, 1D, and 2D NMR) analyses. All compounds were evaluated for their cytotoxic activities on five tumor cell lines.