VISOLTRICIN, A NOVEL BIOLOGICALLY-ACTIVE COMPOUND PRODUCED BY FUSARIUM-TRICINCTUM

The major compound responsible for toxicity to Artemia salina of some Fusarium tricinctum strains has been isolated, and its structure has b een elucidated by spectroscopical methods, i.e. UV, IR, MS, H-1-NMR an d C-13-NMR. The novel compound, trivially named visoltricin, is the fi rst imidazole derivative produced by Fusarium spp., and its structure has been established as the methyl eater of 3-[1-methyl-4-(3-methyl-2- butenyl)-imidazol-5yl]- 2-propenoic acid (molecular formula C13H18N2O( 2); MW = 234.297). Visoltricin was toxic to A. salina larvae (LD(50) = 8.5 X 10(-7) M), and inhibited the growth of six human tumour cell li nes (out of 60 lines tested) at concentrations lower than 10(-5) M. Te sted on rabbit eye it showed an interesting miotic activity similar to that of pilocarpine, a miotic agent largely used in the therapy of gl aucoma. This biological activity could be explained in part by the ant icholinesterase properties shown by visoltricin towards both human ser um and pure enzymes (EC 3.1.1.7 and EC 3.1.1.8). Kinetics studies show ed for visoltricin a mixed-type and reversible inhibition of the EC 3. 1.1.7 enzyme with the competitive inhibition constant(Ki) = 1.9 x 10(- 4) M.