Diketopiperazines from the <i>Cordyceps</i>-Colonizing Fungus <i>Epicoccum nigrum</i>

New diketopiperazines, epicoccins E−H (<b>1</b>−<b>4</b>) and diphenylalazines A (<b>5</b>) and B (<b>6</b>), have been isolated from the solid-substrate fermentation culture of the <i>Cordyceps</i>-colonizing fungus <i>Epicoccum nigrum</i>. The structures of <b>1</b>−<b>6</b> were determined primarily by NMR experiments, and the structure of <b>1</b> was confirmed by X-ray crystallography. The absolute configurations of <b>3</b> and <b>5</b> were assigned using the modified Mosher (<b>3</b>) and Marfey’s (<b>5</b>) methods, respectively. Compounds <b>3</b>−<b>5</b> showed inhibitory effects on HIV-1 replication in C8166 cells.