NOVEL MAMMALIAN-CELL CYCLE INHIBITORS, SPIROTRYPROSTATIN-A AND SPIROTRYPROSTATIN-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 second ary metabolites of Aspergillus fumigatus through a separation procedur e guided by cell cycle inhibitory activity. The structures of spirotry prostatins A and B were determined by spectroscopic methods especially by detailed analyses of their H-1 and C-13 NMR spectra with the aid o f 2D NMR techniques. Spirotryprostatins A and B had a novel structural skeleton with an unique spiro ring system and inhibited the cell cycl e progression of tsFT210 cells at the G2/M phase with IC50 values of 1 97.5 mu M and 14.0 mu M, respectively. Copyright (C) 1996 Elsevier Sci ence Ltd