Three New Indole-Containing Diketopiperazine Alkaloids from a Deep-Ocean Sediment Derived Fungus Penicillium griseofulvum

Three new indole-containing diketopiperazine alkaloids, named variecolorins M-O (1-3) together with the eight known analogues 4-11, were isolated from a deep-ocean sediment-derived fungus. Penicillium griseofulvum. Their structures were determined by analysis of the spectroscopic data. The 2,2-diphenyl-1-picrylhydrazinyl (DPPH) radical-scavenging activities and the cell-proliferation inhibitory activities of the three new compounds 1-3 were investigated.