Aerocyanidin

Aerocyanidin, a new antibiotic containing an isonitrile group, has been isolated from fermentations of Chromobacterium violaceum ATCC 53434. Structure 1 was assigned on the bais of spectroscopic characterization of the antibiotic and of a degradation product that results from treatment with base. The antibiotic is primarily active against Gram-positive bacteria.

During the course of our screening for new antibiotics, Micromonospora echinospora subsp. echinospora Y-03559J was found to produce a novel isonitrile compound, YM-47515 (1) along with a probable degradation product 2. The structure of 1 was assigned by spectroscopic analysis including 2D NMR and IR experiments. The relative stereochemistry of 1 was also proposed by comparison of spectral data with those of a closely related compound aerocyanidin (3). YM-47515 (1) showed promising antimicrobial activity against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA).

Violet-pigmented bacteria, which have been described since the end of the 19th century, are occasionally the causative agent of septicemia and sometimes cause fatal infection in human and animals. Bacteria, producing violet colonies due to the production of a nondiffusible pigment violacein, were classified as a redefined genus Chromobacterium. Chromobacterium violaceum is gram-negative, and saprophyte from soil and water is normally considered nonpathogenic to human, but is an opportunistic pathogen of extreme virulence for human and animals. The biosynthesis and biological activities of violacein and the diverse effects of this pigment have been studied. Besides violacein, C. violaceum produces other antibiotics, such as aerocyanidin and aerocavin, which exhibit in vitro activity against both gram-negative and gram-positive bacteria. 3,6-Dihydroxyindoxazene and Y-TO678h exhibit a selective activity against gram-negative bacteria. Arphamenine A and B, and FR901228, that enhanced immunoresponse, and potentiators of beta-lactam antibiotics and chelators such as ferrioxamine exhibit important clinical potential applications. Lipopolysaccharides and polyhydroxyesters together with several enzymes appear as important metabolites with biotechnological applications. Many of these metabolites were already studied at the genome level.