Metabolic products of microorganisms. 245. Colabomycins, new antibiotics of the manumycin group from Streptomyces griseoflavus. II. Structure of colabomycin A.

Abstract

The structure of colabomycin A (1) was elucidated by a detailed spectroscopic analysis. Two-dimensional NMR spectroscopy experiments provided assignments of the proton and carbon resonances of the tetraene carboxamidechains occurring in 1. The configurations of eight out of nine double bonds were determined by analysis of their coupling constants. The absolute configurations of C-4 (45), C-5 (5R) and C-6 (65) were established from the CD spectra of the parent compound and of 2-(6-Qxo-2,4-hexadienoylamino>5,6-epoxy-l,4benzoquinone (2), which was obtained from 1 by mild chromic acid oxidation. Colabomycin A (1), produced by Streptomyces griseoflavus, belongs to the manumycin group of antibiotics1}. This paper deals with the determination of the chain lengths of the two polyene carboxamideunits, the configurations of their double bonds, and the absolute configurations of the centers of chirality of 1.

Biosynthesis of Colabomycin E, a New Manumycin‐Family Metabolite, Involves an Unusual Chain‐Length Factor

“…This was also confirmed by a NOE contact between H‐8′ and H‐9′ detected in the HSQC‐NOESY spectrum. The structure of 5 is similar to that of the already known metabolite colabomycin A ( 3 ) isolated from Streptomyces griseoflavus 23. However, the upper polyene chain of 5 is two carbons longer.…”

“…The main compound produced by the strain was identified as a new manumycin‐type compound: colabomycin E. At least three other structurally related congeners, including the already known colabomycin A,23, 36 accompanied the major product. The lower carbon chains of colabomycin E and of all its congeners are tetraenes.…”

Activation of a Cryptic Manumycin-Type Biosynthetic Gene Cluster of Saccharothrix espanaensis DSM44229 by Series of Genetic Manipulations

“…The fragments generated from the compound A are shown in Figure 4 in comparison to fragmentation spectra of the triene-type (asukamycin A) and tetraene-type (colabomycin E) manumycins. All three compounds shared the structure of the lower polyketide chain with colabomycins—i.e., tetraene unsaturated lower polyketide chains—but possessed shorter and more saturated upper chains ( Figure 4 ) compared to the most structurally related compounds colabomycin A [ 29 ] and E [ 18 ]. Almost identical spectra as those for compound A were acquired for compounds B and C, too (not shown).…”

Muscarine, oxazole, thiazole, imidazole, and peptide alkaloids, and other miscellaneous alkaloids

“…Dercitine, an alkaloid isolated from a deep-water sponge, contains both an acridine and a thiazole nucleus. This deeppurple compound (23) possesses anti-tumour and immunomodulatory behaviour and was found in a member of the Caribbean sponge of the Dercitus family."' A unique siderophore (microbial iron transport compound) anguibactin (24; R = OH, ab = sat.)…”

“…22 Colabomycin A has been characterized through 2-D NMR as the tetra-ene carboxamide (31). 23 Precursor-directed biosynthesis with Streptomyces parvulus enables new metabolites to be created. Thus the incubation of this fungus with isomeric aminobenzoic acids gives mumumycin analogues such as (32), while production of mumumycin (33) itself was suppressed.…”