Three new 3,6-dioxygenated diketopiperazines, lepistamides A -C (1 -3), along with a known compound, diatretol (4), were isolated from the mycelial solid cultures of the basidiomycete Lepista sordida. Their structures were elucidated by spectroscopic means. The isolated diketopiperazines were evaluated for the cytotoxic activity against Astc-a-1, Bel 7402, and HeLa cell lines, and their biogenetic pathway was discussed.Introduction. -Recently, much attention has been paid to higher basidiomycetes because of their potential as a source of biologically active substances [1]. Lepista sordida (Schumach. ) Singer, a basidiomycetous fungus of the family Tricholomataceae, is an edible agaric species [2]. Two diterpenes (lepistal and lepistol) with the activity to induce differentiation in human leukaemia cells were previously isolated from the culture filtrate of this fungus [3]. During a screening for bioactive metabolites produced by macrofungi collected from South China, an EtOH extract from the mycelial solid cultures of a strain (GIM 5.315) of this basidiomycete showed cytotoxic activity against HeLa cells and antibacterial activity against Staphylococcus aureus. The metabolites of this fungus were therefore investigated. Three new diketopiperazines, trivially named lepistamides A -C 1 ) (1 -3), and a known one, diatretol (4) [4], were isolated from the mycelial cultures of the basidiomycete. The isolation, structure elucidation, and possible biogenetic pathway of these new compounds are described as follows.
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