Pradimicins L and FL: new pradimicin congeners from. Actinomadura verrucosospora subsp. neohibisca.

Abstract

Pradimicin L, a new congener of pradimicin A having the D-glucosyl-D-thomosamine moiety at the C-5 position, was isolated from Actinomaduraverrucosospora subsp. neohibisca subsp. nov. The structure of pradimicin L was deduced to be N- [[(5S;6S>5-0-[4,6-dideoxy-4-(methylamino Pradimicins A, B, C1 "4*, D, E5), FA-1 and FA-26) were previously reported to exhibit broad activity against pathogenic fungi and yeasts. They share 5,6-dihydrobenzo[a]naphthacenequinone as the common skeleton and can be distinguished from each other in the amino acid moiety (D-alanine1~4), glycine5) and D-serine6)) and in the 4'-amino group of D-thomosamine in the disaccharide moiety. Benanomicin A, which also has a 5,6-dihydrobenzo[#]naphthacenequmone skeleton, was reported to have D-alanine as the amino acid moiety and D-xylosyl-D-fucose as the C-5 disaccharide moiety7'8). In the continued search for new antifungal compounds, a new strain of Actinomadura numbered R103-3 was originally discovered which produced pradimicin L. Based on taxonomic studies described in this paper, Actinomadura verrucosospora subsp. neohibisca subsp. nov. is proposed here for strain R103-3. Comparedwith knownpradimicin analogs, pradimicin L was found to differ by a distal D-glucose in the C-5 disaccharide moiety. Like pradimicins FA-1, FA-26) and BMS-1811849), pradimicin FL was produced by directed biosynthesis in D-serine-supplemented medium so that the D-alanine moiety of pradimicin L could be replaced by D-serine. This paper deals with the taxonomy of strain R103-3, structure elucidation of pradimicins L and FL and their antifungal evaluation. Materials and MethodsTaxonomy

Cloning and Nucleotide Sequence of the Putative Polyketide Synthase Genes for Pradimicin Biosynthesis fromActinomadura hibisca

“…neohibisca. ll ,12) Feeding experiments with [l- 13 CJacetate and [1,[2][3][4][5][6][7][8][9][10][11][12][13] CJacetate showed that the aglycon of PRM A is derived from a dodecaketide,13) suggesting that PRM-A is synthesized by a type I or II PKS. There are no reports about PKSs for the biosynthesis of antibiotics with a dihydrobenzo[aJnaphthacenequinone aglycon, or about antibiotic biosynthetic genes from the genus Actinomadura.…”

Characterization and identification of pradimicin analogs from Actinomadura hibisca using liquid chromatography–tandem mass spectrometry

“…A number of peaks were detected based on the protonated molecular ions of the PRs listed in Fig. 1a whose presence was previously established from earlier specialized studies of large-scale fermentation, flash chromatographic isolation, and NMR [5][6][7][8][9][10]22]. Profiling using HPLC-ESI-MS/MS appears to be a simple and sensitive alternative to conventional large-scale fermentation and isolation for identifying each PR without prior chromatographic separation if the PR structures are predictable by MS/MS fragmentation patterns or are already known.…”

“…In particular, a difference of 89 Da between m/z 709 and 620 could be used as one of the diagnostic fragmentation patterns for Alacontaining PR congeners. There are three additional Ala-containing PRs -PRB, PRC and PRL -present in A. hibisca fermentation [6,9]. By selection of their protonated molecular ions at m/z 709, 827 and 871, four peaks with Rt of 22.5, 26.2, 29.6 and 31.2 min were subjected to HPLC-ESI-MS/MS analysis (Table 2 and Fig.…”

“…To date, PR analogs have been isolated from pilot-scale fermentations using flash chromatography and separately structurally elucidated by nuclear magnetic resonance (NMR) spectroscopy [6][7][8][9][10]. However, there has been no report of systematic HPLC profiling of PRs and their intermediates biosynthesized from A. hibisca.…”

“…Since the first isolation of pradimicin A (PRA) as a major product from a producing strain [5], there have been a number of reports on pradimicin (PR) congeners, which possess a benzo[␣]naphthacene aglycone as a common aromatic polyketide backbone, but are distinctly decorated with diverse combinations of both amino acids -including D-alanine (Ala), D-glycine (Gly) or D-serine (Ser) -and sugar moieties, such as thomosamine (Tho), des-N-methyl-thomosamine (DMTho), xylose (Xyl) or glucose (Glu) (Fig. 1a) [6][7][8][9][10]. PRA contains Ala, Tho, and Xyl as the appendage scaffolds; pradimicin B (PRB) does not have Xyl; and pradimicin C (PRC) contains DMTho instead of Tho aminosugar.…”