MPC1001 and its analogues: new antitumor agents from the fungus Cladorrhinum species.

[structure: see text] Eight new compounds, MPC1001 and MPC1001B-H, were isolated from the fungus Cladorrhinum sp. KY4922. Multiple NMR experiments and CD data revealed MPC1001 to be an O-methyl derivative of emestrin, a 15-membered antifungal antibiotic containing a unique epidithiodioxopiperazine skeleton. Other compounds were elucidated to be structurally related novel analogues. MPC1001 and the analogues exerted potent antiproliferative activities against a human tumor cell line.