AMIDOMYCIN, A NEW ANTIBIOTIC FROM A STREPTOMYCES SPECIES, CHEMICAL STRUCTURE

Abstract

Amidomycin, an antibiotic active primarily against yeast, has been isolated from a Streptomyces species. The Compound C₁₀H₆₈O₁₂N₄. is neutral, optically active, and shows no unsaturation nor characteristic light absorption maxima. It is composed of 4 moles each of D(−)-valine and D(−)-α-hydroxyisovaleric acid, linked alternately by ester and amide bonds to form a 24-membered ring (I). This structure is assigned from the following observations: on mild alkaline hydrolysis 4 moles of alkali are consumed with formation of a hydroxy acid, C₁₀H₁₉O₄N (II). The latter on distillation gave a crystalline lactone, C₁₀H₁₇O₃N, considered to be 3,6-diisopropyl-2,5-diketomorpholine (III), which was hydrolyzed to give 1 mole each of D(−)-valine and D(−)-α-hydroxyisovaleric acid.Amidomycin is closely related to valinomycin, an antibiotic isolated from Streptomycesfulvissimus and shown to be a 24-membered ring compound containing D(−)-valine, D(−)-α-hydroxyisovaleric acid, L(+)-valine, and L(−)-lactic acid. It also resembles the enniatins, produced by certain species of Fusarium, but differs from these compounds in the number of units in the ring structure as well as in containing D(−)-valine rather than an N-methyl-L-amino acid.