Mycoleptodiscins A and B, Cytotoxic Alkaloids from the Endophytic Fungus <i>Mycoleptodiscus</i> sp. F0194

Two novel reddish-orange alkaloids, mycoleptodiscin A (<b>1</b>) and mycoleptodiscin B (<b>2</b>), were isolated from liquid cultures of the endophytic fungus <i>Mycoleptodiscus</i> sp. that had been isolated from <i>Desmotes incomparabilis</i> in Panama. Elucidation of their structures was accomplished using 1D and 2D NMR spectroscopy in combination with IR spectroscopic and MS data. These compounds are indole-terpenes with a new skeleton uncommon in nature. Mycoleptodiscin B (<b>2</b>) was active in inhibiting the growth of cancer cell lines with IC<sub>50</sub> values in the range 0.60–0.78 μM.