Novel mammalian cell cycle inhibitors, spirotryprostatins A and B, produced by Aspergillus fumigatus, which inhibit mammalian cell cycle at G2/M phase

Two novel diketopiperazine alkaloids, spirotryprostatins A and B, were isolated as new inhibitors of the mammalian cell cycle from me secondary metabolites of Aspergillus fumigatus through a separation procedure guided by cell cycle inhibitory activity. The structures of spirotryprostatins A and B were determined by spectroscopic methods especially by detailed analyses of their H-1 and C-13 NMR spectra with the aid of 2D NMR techniques. Spirotryprostatins A and B had a novel structural skeleton with an unique spiro ring system and inhibited the cell cycle progression of tsFT210 cells at the G2/M phase with IC50 values of 197.5 mu M and 14.0 mu M, respectively. Copyright (C) 1996 Elsevier Science Ltd