Biosynthesis of mucidin, an antifungal antibiotic from basidiomycete Oudemansiella mucida 2H-, 13C-, and 14C-labelling study

Incorporation of 2H-, 13C- and 14C-labelled precursors into mucidin (I) was studied by mass and 13C NMR spectroscopy and chemical degradations. Biosynthesis of I is connected with shiki-mate and acetate-malonate pathways. Methionine participates on the C- and O-methylation.

Cycloheptatriene dimers: New precursors of diamantane

Dimerization of cycloheptatriene, catalyzed by titanium complexes, afforded pentacyclo[8.4.0.03,7.04,14.06,11]tetradeca-8,12-diene (I) (10%) and pentacyclo[7.5.0.02,8.05,14.07,11]tetradeca-3,12-diene (II) (90%). Structure of both dimers and their derivatives was determined by means of 1H NMR, 13C NMR and mass spectra. On heating, the diene II was converted into the more stable isomer I. On hydrogenation and further catalytic isomerization, both I and II gave diamantane in high yield.

Epimer of 7-deoxyaklavinone

The structure (9R,10S)-7-deoxyaklavinone (VII) was assigned to a minor metabolite isolated from Streptomyces coeruleorubidus on the basis of 1H, 13C NMR and CD spectra. Evidence that compounds II and VII, isomeric with 7-deoxyaklavinone, are natural compounds is presented.

Xanthomegnin and viomellein derivatives from submerged cultures of the ascomycete Nannizzia cajetani

Antibacterial metabolites isolated from a submerged culture of the ascomycete Nannizzia cajetani AJELLO grown on wort medium were spectroscopically identified as dimeric naphthoquinone derivatives xanthomegnin (I), viomellein (II), 3,4-dehydroxanthomegnin (III) and two, not previously described pigments: 3',4'-dehydroviomellein (IV) and 3,4,3',4'-bisdehydroxanthomegnin (V).

New anthracycline antibiotics produced by interspecific recombinants of streptomycetes. III. Isolation and structure of iremycin

The structure of the anthracycline antibiotic iremycin isolated from Streptomyces violaceus subspecies iremyceticus has been elucidated as 10-(alpha-L-rhodosaminyl)-gamma-rhodomycinone (I) on the basis of spectroscopic analyses and chemical reactions.

Accumulation of 2-oxo acids in mutants of Aspergillus niger requiring lysine

Mutants of Aspergillus niger 194A and 178 requiring lysine differ from the original prototrophic strain K10 and from each other on the course of accumulation of organic acids. In both mutants less citric acid accumulates during the first phase of cultivation but considerably more 2-oxoglutarate and 2-oxoadipate accumulate than in the original strain. Whereas in the 194A mutant this state remains unchanged also during the second phase of cultivation, in the 178 mutant oxo acids are degraded and citric acid is synthesized intensively. The accumulation of 2-oxoglutarate and 2-oxoadipate in the fermentation medium indicates that in A. niger lysine is synthesized via the homocitrate pathway.

On the interaction of caffeine with nucleic acids. III. 1H NMR studies of caffeine--5'-adenosine monophosphate and caffeine-poly(riboadenylate) interactions

1) The self-association of both caffeine (Cf) and 5'-adenosine monophosphate (AMP) in aqueous solution has been reinvestigated by 1H NMR. The self-association process is characterized by an isodesmic model. The apparent self-association constants of the vertical stacking process are KCf = (10.6 +/- 1.0) M-1 and KAMP = (1.67 +/- 0.17) M-1. The arrangement of the monomeric units in the stacked aggregates is discussed in terms of isoshielding curves theoretically calculated by Giessner-Prettre and Pullman. Models are proposed which are consistent with these and further previous NMR data. 2) The interaction of Cf and AMP has been studied by 1H NMR. The apparent association constant of the complex Cf-AMP is KC-A = (7.3 +/- 1.2) M-1. Two models of the mutual arrangement of AMP and Cf in the complex are proposed on the basis of the calculated isoshielding curves considering both ring current and local atomic diamagnetic anisotropy effects. 3) The interaction of Cf and poly(riboadenylate), (rA)n, is indicated by a downfield shift of the H-8 line but an upfield shifts of the H-2 line in the 1H NMR spectra of (rA)n. The concentration dependence of the 1H NMR shifts of both Cf and (rA)n can be explained by the existence of two binding mechanisms. We suggest (i) partial insertion of Cf between adjacent base residues of ordered single-stranded regions of (rA)n and (ii) outside binding of Cf in form of monomeric Cf as well as of self-associated aggregates. The complex geometry of insertion proposed on the basis of the calculated isoshielding curves is characterized by a stronger overlapping of the Cf ring and the H-2 proton of (rA)n as compared to the H-8 proton.

Oxynemorensine, an alkaloid from Senecio nemorensis L., var. subdecurrens GRISEB

From S. nemorensis L., var. subdecurrens GRISEB. there were isolated the previously obtained alkaloids nemorensine (I), retroisosenine (II), bulgarsenine (III) and, in addition, the alkaloid oxynemorensine which was assigned the structure VIII on the basis of the interpretation of the 1H-NMR, 13C-NMR, mass spectra, and on that of the identification of the products of hydrolysis and reduction. Furthermore, the isolation of the cis-nemorensic acid (V) as well as that of the unsaturated acid IV, and the transformation of bulgarsenine (III) to nemorensine (I) were described.

Naphthacenequinone derivatives from a mutant strain of Streptomyces coeruleorubidus

Five metabolites were isolated from a mutant strain of Streptomyces coeruleorubidus. Structures IX-XIII were proposed on the basis of their 1H and 13C-NMR, IR, UV/VIS and mass spectra.

New rhodomycinone from the strain Streptomyces griseoruber 4620

New anthracyclinone, 10-deoxy-β-rhodomycinone (V), was isolated from the strain Streptomyces grisoeruber 4620 besides β-rhodomycinone (I), β-isorhodomycinone (II), α2-rhodomycinone (III), and ε-rhodomycinone (IV). The identification and the structure elucidation are based on the UV, CD, IR, 1H-NMR and mass spectra.

Anthraquinones related to anthracyclinones from the mutant strain Streptomyces galilaeus J-14

The anhydro derivative of ε-pyrromycinone IX and three anthraquinones X-XII related to anthracyclinones were found as minor metabolites of the mutant strain Streptomyces galilaeus J-14. Proposed structures are based on the spectroscopic measurements.

13C NMR study of tetrosides and their derivatives

13C NMR spectra of 23 tetrose derivatives were assigned. The C(1) resonates below 103 ppm with compounds having cis-arranged substituents at C(1) and C(2) and above 106 ppm with compounds having trans-arrangement. The carbon-13 chemical shifts are mainly influenced by the 1,2-interaction. The magnitudes of direct coupling constants 1J(C(1), H) cannot be used for the determination of the anomeric configuration.

Conversion of monosaccharides into their corresponding 2-glycosuloses by intact cells of the basidiomycete Oudemansiella mucida

The production of D-arabino, D-lyxo, and D-ribo-2-hexosuloses and D-threo-2-pentosuloses from their respective aldoses was demonstrated with washed mycelium suspensions of the basidiomycete Oudemansiella mucida. L-Sorbose was shown to be converted into D-threo-2,5-hexodiulose. The dicarbonyl sugar produced were isolated as their hydrazones, whose structures were inferred from spectroscopic evidence and the method of preparation.

Products of the acid hydrolysis of 7-chloro-1,3-dihydro-3-hydroxy-5-phenyl-2H-1,4-benzodiazepin-2-one (oxazepam)

The acid hydrolysis of oxazepam (Ib) was studied. Under various reaction conditions 6-chloro-4-phenylquinazoline-2-carbaldehyde (V) and the compounds VI and VIII were identified among the products besides the expected 2-amino-5-chlorobenzophenone (IVb).

8-Hydroxyergotamine, a new ergot alkaloid

A new alkaloid was found in the mother liquors remaining after the isolation of ergotamine from the natural ergot. The structure of 8-hydroxyergotamine was assigned by the spectroscopic methods.

Eurotium (Aspergillus) repens metabolites and their biological activity

Eurotium repens mycelium cultivated under static conditions was used to isolate and identify metabolities--echinulin, physcion, erythroglaucin, flavoglaucin and asperentin; the filtrate of the culture yielded asperentin 8-methylether. The broadest biological activity spectrum was displayed by asperentin which had antibacterial and antifungal effects and, at a concentration of 86 microgram/ml, caused 50% mor7 tality in Artemia saline larvae. The highest cytotoxicity towards HeLa cells was found in physcion which caused 50% growth inhibition at a concentration of 0.1 microgram/ml.

The structure of ekatetrone, a metabolite of strains of Streptomyces aureofaciens

The structure of ekatetrone has been determined from physico-chemical data obtained using the natural compound, its derivatives and products of degradation reactions. Ekatetrone was found to be the lactone of 1,8-dihydroxy-2-(1'-hydroxy-2'-carbamoyl)ethyl-9,10-anthraquinone-3-acetic acid (I). It is proposed that ekatetrone is related, biogenetically, to protetrone.

Glucose-2-oxidase activity and accumulation of D-arabino-2-hexosulose in cultures of the basidiomycete Oudemansiella mucida

Submerged cultures of the basidiomycete Oudemansiella mucida, strain III, accumulate D-arabino-2-hexosulose. The maximum yields during cultivations in shaker flasks or in a laboratory fermentor are 6--12 and 15 mg/ml, respectively (20--50% conversion of substrate glucose). The accumulation is transient, the aldoketose being again utilized after glucose exhaustion. Its production is stimulated by fluoride ions. The enzyme responsible for the C(2)-specific oxidation of D-glucose acts as an intracellular oxidase with a maximum activity in the exponential phase of growth. D-arabino-2-Hexosulose was also detected in the cultivation medium of the wood-rotting fungi Pleurotus ostreatus, Laetiporus sulphureus, and Phellinus abietis.

2,2'-dimethoxy-4a,4a'-dehydrorugulosin (rugulin), a minor metabolite from Penicillium rugulosum

A new metabolite was isolated from the culture of Penicillium rugulosum and its structure was determined from physico-chemical data. Accompanying metabolites skyrin and rugulosin were characterized by UV, IR, CD, mass and NMR spectra.

Microbial transformation of daunomycinone by Streptomyces aureofaciens B-96

Daunomycinone, aglycone of the anthracycline antibiotic daunomycin, was transformed by a washed mycelia of Streptomyces aureofaciens B-96 in a buffer solution containing sucrose; the obtained product, dihydrodaunomycinone (9-(1-hydroxyethyl)-7,8,9,10-tetrahydro-6,7,9,11-tetrahydroxy-4-methoxy-5,12-naphthacenequinone), was identified by measuring basic physicochemical characteristics (IR, UV and visible spectra, mass spectra and NMR, optical rotation and m.p.).