[The structure of granaticin and of granaticin B. 1. Spectroscopic charcteristics and chemical analysis]

Total synthesis of the postulated structure of fulicineroside

A total synthesis of the proposed structures of fulicineroside and its aglycone fulicinerine is reported. The tetrasubstituted dibenzofuran substructure was accessible either through a Pd-mediated ortho-metalation or by an Ir-catalyzed meta-borylation. The synthesis of the β,β,α-linked trisaccharide consisting of D-olivose, L-rhodinose, and L-rhamnose was challenged by the unprecedented β-linked rhodinose. A Pd-catalyzed β-selective glycosylation of a 4-epi-rhodinose and a subsequent Mitsunobu inversion provided selectively the β-linked L-rhodinose-L-rhamnose disaccharide. Comparison with the reported data for the natural product and the aglycone suggests a misassignment of the structure of the natural product.

Identification of secondary metabolites from Streptomyces violaceoruber TU22 by means of on-flow LC-NMR and LC-DAD-MS

For rapid screening of natural products from Actinomycetes, a combination of on-line couplings LC-NMR, LC-DAD-MS and HPLC-PDA, as well as MALDI-TOF-MS is particularly suitable. Simultaneous use of these coupling techniques provides considerable advantages for the rapid identification of natural compounds in mixtures. The results of our present investigation on secondary metabolite products of Streptomyces violaceoruber TU 22 showed that more than 50% of the identified metabolites are new compounds. The structures of four new polyketides (granaticin C, metenaticin A, B and C) as well as four known ones (granaticin A, granatomycin E, daidzein and genistein) have been elucidated using LC-NMR, LC-MS/MS and -MS(n) techniques in combination with two-dimensional NMR spectroscopy.

Conformational features of rhamnopyranose derivatives. The molecular structure of methyl 2,3,4-tri-O-acetyl-alpha-L-rhamnopyranoside

Methyl 2,3,4-tri-O-acetyl-alpha-L-rhamnopyranoside, C13H20O8, M(r) = 304.3, is monoclinic, space group C2, with a = 23.619(1), b = 8.2168(5), c = 19.093(1) A, beta = 118.72(1) degrees, V = 3249.6(8) A3, Dc = 1.244 g cm-3, mu (MoK alpha) = 0.97 cm-1 and Z = 8. The structure was refined to R = 0.044 and Rw = 0.039 for 1969 observed reflections. There are two independent molecules in the asymmetric unit. The bond lengths and bond angles of the pyranose rings of the two are in good agreement within the limits of error. The molecules have similar conformation except for the orientation of one of the acetoxy groups. Each molecule is a normal 1C4 chair with Cremer-Pople puckering parameters Q = 0.557(6) A, theta = 174.6(2) degrees and psi = 144.6(9) degrees for molecule A and 0.564(4) A, 177.9(1) degree and 30.8(8) degrees for molecule B, respectively. The acetyl groups have the planar, (S)-cis conformation most commonly observed. They are oriented with the acetyl planes within +/- 35 degrees of the C-H bond at the ring carbon atom to which they are attached.

[Naphthoquinone antibiotics from Streptomyces lateritius. I Fermentation, isolation and characterization of granatomycins A, C, and D]

The fermentation and isolation procedures of the antibiotic granatomycin produced by Streptomyces lateritius are described. Furthermore, the producing strain ZIMET 43 627 and the main constituents of granatomycin will be characterized. Granatomycin is a red-violet pigment antibiotic of the naphthoquinone type. The physicochemical properties of granatomycin resemble those of granaticin. The antibiotic can be isolated from culture filtrates and from the mycelium by extraction with lower aliphatic alcohols. It can be purified by gel filtration methods. Granatomycin displays antimicrobial activity, particularly against grampositive and gramnegative bacteria, and antiviral activity against fowl-plaque-virus in mammalian cells. Granatomycin is useful in selection of resistant mutants of bacteria and viruses with decreased virulence but high immunogenity suitable for use as life vaccines against infection diseases. The physicochemical properties of the main constituents of granatomycin studied confirm the identity of granatomycin C with granaticin and the identity of granatomycin D with dihydrogranaticin Granatomycin A is identical with the well-known semisynthetic methylester of dihydrogranaticin. Therefore, the production of granatomycin A is the first possibility to produce this derivative of granaticin biosynthetically.

Interaction of granaticin B with the transcription system of Bacillus subtilis

The interaction of granaticin B, a quinone antibiotic produced by Streptomyces granaticolor, with some biologically important bivalent metal ions, DNA and ATP was demonstrated spectrophotometrically. The activity of isolated RNA polymerase was higher when the DNA of phage SP 50 served as template than with DNA isolated from Bacillus subtilis. Granaticin B inhibited in vitro RNA synthesis, similarly to certain other antibiotics (the inhibition was three times lower than that caused by actinomycin D or streptolydigin and slightly higher than that by epsilon-pyrromycinone). The inhibitory effect was higher when the Mg2+ concentration in the reaction mixture was decreased. The inhibition was then proportional to the concentration of the DNA template. DNA-dependent RNA synthesis is thus inhibited in vitro by granaticin B but this does not appear to be the only site of action of this antibiotic in vivo.