Enaminomycin B

The structures of enaminomycins A and B were determined by their physico-chemical properties and X-ray crystallographic analyses to be 4-amino-2,5-dioxo-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid and 2-oxo-4-amino-5-hydroxy-5-acetonyl-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid, respectively. The structure of enaminomycin C was also determined by the analysis of NMR spectrum and other physico-chemical properties to be 2-oxo-4-amino-5-hydroxy-7-oxa-bicyclo[4,1,0]hept-3-ene-3-carboxylic acid.

Physico-chemical characterization of enaminomycins revealed that these antibiotics are new members of the epoxy quinone family. From elementary analysis and mass spectroscopic measurements the molecular formulae of enaminomycins A, B and C appear to be C7H5NO5, C10H11N06 and C7H7NO5, respectively. They are very unique in their chemical properties, possessing various functions, such as epoxy, primary amine and carboxylic acid, in their small structural units. Enaminomycin A, the most potent component, has activity against Gram-positive and Gram-negative bacteria and shows cytostatic effect on L1210 mouse leukemia cells in vitro, but enaminomycins B and C are only weakly active against Gram-positive and Gram-negative bacteria.

Chemical profiling of a Streptomyces griseus strain isolated from an old building with moisture damage led to the discovery of two novel phenoxazinones, chandrananimycin D and pitucamycin , along with the known grixazone B. Pitucamycin represents an unprecedented hybrid molecule composed of a phenoxazinone and an enaminomycin-like epoxyquinone moiety.