STRUCTURE ELUCIDATION AND CHEMICAL SYNTHESIS OF STIGMOLONE, A NOVEL TYPE OF PROKARYOTIC PHEROMONE

Approximately 2 mu mol of a novel prokaryotic pheromone, involved in s tarvation-induced aggregation and formation of fruiting bodies by the myxobacterium Stigmatella aurantiaca, mere isolated by a large-scale e lution procedure. The pheromone was purified by HPLC, and high-resolut ion MS, IR,H-1-NMR, and C-13-NMR mere used to identify the active subs tance as the hydroxy ketone 2,5,8-trimethyl-8-hydroxy -nonan-4-one, wh ich has been named stigmolone, The analysis was complicated by a solve nt-dependent equilibrium between stigmolone and the cyclic enol-ether ihydro-2,2,5-trimethyl-6-(2-methylpropyl)-2H-pyran formed by intramole cular nucleophilic attack of the S-OH group at the ketone C4 followed by loss of H2O. Both compounds were synthesized chemically, and their structures mere confirmed by NMR analysis, Natural and synthetic stigm olone have the same biological activity at cn. 1 nM concentration.