Structural elucidation of minimycin, a novel C-ribonucleoside antibiotic, which was established as 5-β-D-ribofuranosyl-1, 3-oxazin-2, 4-dione (I), and structural relationship to β-pseudouridine are described.
Examination of the antibiotic metabolites of Penicillium herquei BAINIER and SARTORY showed two minor components accompanying atrovenetin, the main active substance. One of these was identified as deoxyherqueinone. The other, herqueichrysin, was a new compound. Chemical and spectroscopic investigation indicated that it was a C20H20O6 phenalenone derivative related in structure to deoxyherqueinone. D.emethylation of herqueichrysin yielded a product isomeric with, but different from, atrovenetin. The similar PMR and mass spectra of the two compounds suggest that the differences lie only in the position at which the dihydrofuran ring is fused to the phenalenone. In addition to these antibiotics physcion and physcion anthranol were present in cultures of P. herquei.
Diumycin, a phosphorus-containing glycolipid antibiotic, is produced by Streptomyces umbrinus ATCC 15972. It is active against gram-positive bacteria and, to a lesser degree, against gram-negative bacteria. Diumycin affects dividing but not resting cells of Staphylococcus aureus FDA 209 P. The antibiotic is strongly bound by serum. Although primarily bacteriostatic at levels approximating the minimum inhibitory concentration, it is bactericidal at higher levels. Diumycin is active upon subcutaneous administration to mice infected with Streptococcus pyogenes C 203 and Diplococcus pneumoniae and, like other members of the phosphorus-containing glycolipid antibiotic group, demonstrates a unique prophylactic activity against these infections. High and prolonged serum levels (lasting several weeks) were achieved in the plasma of dogs and monkeys after a single, parenteral dose of the antibiotic, and small to moderate amounts of bioactivity were recovered in the urine. Toxicity studies indicate that diumycin is well-tolerated in mice, but may cause a transient liver damage at dose levels near the LD50.
Melinacidins II, III and IV are new antibacterial agents produced by Acrostalagmus cinnabarinus var. melinacidinus. All three melinacidins belong to the "3, 6-epidithiadiketopiperazine" group of antibiotics, and appear to be related to but distinct from chaetocin and verticillin A.
A new antimetabolite of arginine and metabolically related compounds was isolated from a fermentation broth produced by an unclassified Streptomycete. The structure was shown to be L-N5-(1-iminoethyl) ornithine and the compound was synthesized by reaction of the copper complex of L-ornithine with ethyl acetimidate. Mild base hydrolysis of the compound gave the expected products, L-ornithine and L-N5-acetylornithine and, in addition, a rearranged product, L-N2-acetylornithine. Arginase hydrolyzed the antimetabolite to L-ornithine.