Physiochemical characterization of substituted chromeno[4,3-b][1,5]benzodiazepine stereoisomers designed as cell membrane active antitumor agents.

As an alternative to naturally occurring pyrrolo[2,1-c][1,4]benzodiazepines (e.g., antramycin) which possess properties of DNA alkylation, we have designed several antileukemic chromeno[4,3-b][1,5]benzodiazepine derivatives with potential activity toward leukemia cell membranes and the cyclic nucleotide system. The cis and trans diastereoisomers were characterized by NMR. The absolute configurations of the enantiomers were established by X-ray diffraction and circular dichroism (CD) measurements. By means of absorption spectroscopy and determinations of fluorescence and fluorescence decay, it was found that the cancerostatically active compound (+)(6aR, 13aS)-3,4-dimethoxy-10,11-dimethyl-6,6a,7,8,13, 13a-hexahydrochromeno[4,3-b][1,5]benzodiazepine (ZIMET 54/79) and its biologically inactive (-) enantiomer (ZIMET 55/79) interact with liposomal membranes. At pH values of 6.0 and 7.3 the long-wave absorption bands of these agents showed weak bathochromic and hypochromic effects upon addition of neutral, and positively and negatively charged phosphatidylcholine and phosphatidylcholine/cholesterol liposomes. Such spectral changes are interpreted as resulting from the binding of both agents to phospholipid bilayers. Steady-state determinations using the membrane probe 1-anilino-8-naphthalenesulfonic acid (1,8-ANS) led to the observation of a small decrease in fluorescence intensity in the presence of either agent. Time-resolved measurements demonstrate that the mechanism of action of the agents occurs mainly through the partial displacement of probe molecules from regions of hydrophobic binding to areas of greater solvent accessibility. No significant differences in binding between the cancerostatically active and inactive enantiomers with liposomes (archiral systems) were detectable on the basis of spectrophotometric and fluorescence determinations. Cell membrane bound adenylate cyclase is stimulated by ZIMET 54/79, resulting in an increase of 103% in the level of cAMP in mouse L1210 leukemia cells. On examination of structure-activity relationships, it was found that the biological activity (leukemia L1210, P388, Lewis lung carcinoma, melanoma B16, increase in cAMP) is correlated with the particular configuration (6aR,13aS) and type of substituent at positions 3 and 4 of the benzo ring in the case of alkoxy groups and positions 10 and 11 for methyl groups. No activity was detected toward DNA/RNA using microbial test systems.

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.

Chrysospermins, new peptaibol antibiotics from Apiocrea chrysosperma Ap101.

Four new members of peptaibol antibiotics, designated as chrysospermins A, B, C, and D, were isolated from the mycelium of Apiocrea chrysosperma Ap101 by solvent extraction, silica gel chromatography and preparative recycling HPLC. Their structures as new nonadecapeptides were settled by detailed spectroscopic analysis and chemical degradation experiments. The chrysospermins display antibacterial and antifungal activity, and induce pigment formation by the fungus Phoma destructiva.

Aurantimycins, new depsipeptide antibiotics from Streptomyces aurantiacus IMET 43917. Production, isolation, structure elucidation, and biological activity.

Aurantimycins A (1), B (2) and C (3) were isolated from the mycelium of Streptomyces aurantiacus JA 4570 as new representatives of the azinothricin group of hexadepsipeptide antibiotics. Their structures were settled by X-ray diffraction analysis of crystalline aurantimycin A (1), high field homo- and heteronuclear 2D NMR experiments, high-resolution mass spectrometry and amino acid analysis. Aurantimycins are characterized by a new side chain containing fourteen carbon atoms. They display strong activity against Gram-positive bacteria and cytotoxic effects against L-929 mouse fibroblast cells.

Helioferins; novel antifungal lipopeptides from Mycogone rosea: screening, isolation, structures and biological properties.

Helioferins A and B were detected as novel aminolipopeptides in cultures of Mycogone rosea DSM 8822 in the course of a screening for mediators of helianthate anion transfer from aqueous to toluene phases. Their structures as novel antibiotics and cytotoxic agents were elucidated by mass spectrometry and NMR spectroscopic methods. Antimicrobial activity was estimated against Candida albicans and Gram-positive bacteria including Mycobacterium spp.

Lipohexin, a new inhibitor of prolyl endopeptidase from Moeszia lindtneri (HKI-0054) and Paecilomyces sp. (HKI-0055; HKI-0096). I. Screening, isolation and structure elucidation.

Lipohexin was isolated as a novel lipohexapeptide (I) (C39H68N6O9) from three fungal strains, Moeszia lindtneri HKI-0054, Paecilomyces sp. HKI-0055 and Paecilomyces sp. HKI-0096. The structure was elucidated by detailed mass spectrometric and NMR experiments. The proline-containing peptide displays moderate antibacterial activity against Bacillus subtilis ATCC 6633 and inhibits competitively the prolyl endopeptidase from human placenta.

Inhibitors of the cleavage of aclacinomycins.

The reductive cleavage of the aclacinomycins A (I), Y (II), and B (III) by intact mycelia or subcellular fractions of the producer strain S. spec. AM 33352/F43 is suppressed in the presence of uncouplers, complex-forming agents, detergents, and some metal anions such as chromate. Increased concentration of the latter in complete cultures caused rearrangement of I to III.

Synthesis and biological evaluation of 4,4-dimethyl-5,5-di(1-methylethyl)-2,3,4,5-tetrahydro-1 H-dipyrrolo[3,4-d:2,1-f][1,2]azasiline-1,3-dione and other pyrrolediones as new antibacterial active agents.

The UV-light induced photosubstitution of 3,4-dibromo-2,5-dihydro-1H-2,5-pyrroledione (2) [1] with pyrrole derivatives leads to 3-mono- and 3,4-disubstituted pyrrolediones depending on the starting material. These pyrrole homologues of arcyriarubin A (1) are further processed by nucleophilic substitution of the remaining bromine substitutent with pyrrolidine. Cleavage of the protecting group affords the free pyrrole substituents. By UV-light irradiation the azasiline-system (6) is accessible, and its structure was established by X-ray methods. The in vitro antibacterial activity of the pyrrolediones was evaluated, and a strong activity of the compounds 4, 7, 8 and 12 against the methicillin- and ciprofloxacin-resistant bacterium Staphylococcus aureus 134/94 was established.

[Protein binding of the macrolide antibiotic turimycin. Methodologic effects on results]. / Untersuchungen zur Proteinbindung des Makrolid-Antibioticums Turimycin Methodische Einflüsse auf die Ergebnisse.

A methodological investigation deals with the binding of the macrolide antibiotic turimycin to bovine serum albumin (BSA) and serum proteins. On this occasion, it is pointed out that, especially when serum is used, the critical evaluation of the analytical method is of the same importance as the utilization of standardized procedures for the quantification of the protein binding in the sense of general comparability. This concerns, for example, the chemistry of the reaction used for detection, the formation of degradation products of the active principle in the serum during the study of the binding and possible repercussions on the chemical determination, the electrolyte content of the sample in the punched hole of the microbiological test plate, losses of activity or synergistic effects of the serum-antibiotic combination during incubation of microbiological test plates after termination of the equilibrium dialysis. The determination of binding constants by means of a competitive fluorescence titration, the chemical analysis of equilibrium dialyses and their parallel assessment with the aid of the agar-diffusion plate test led to results which were not in agreement with each other. Turimycin which is very slightly soluble at pH = 7.4 and fairly soluble at pH = 5.0, is practically not bonded at the lower pH value of BSA and serum proteins (fluorescence titration of BSA: Kb approximately 20; equilibrium dialysis and chemical evaluation). The microbiological determination in serum on the basis of equilibrium dialyses yields higher values for the binding of turimycin.(ABSTRACT TRUNCATED AT 250 WORDS)

[Relationships between structure and activity of anthracycline antibiotics of the rhodomycin group: inhibition kinetics of DNA and RNA viruses of the double- and single-strand types]. / Beziehungen zwischen Struktur und Wirkung von Anthracyclin-Antibiotika der Rhodomycingruppe: Hemmungskinetik der DNS- und RNS-Viren vom Doppelstrang- und Einstrang-Typ.

Antiviral activity from anthracycline antibiotics of rhodomycin-type was investigated by two independent methods, which determined the infectious units and antigenity of incomplete virions. The action of rhodomycin was dependent on structure, number and position of amino sugar, which is in aglycon. The viruses of double-stranded DNA and RNA viruses was stronger inhibited as single-stranded RNA viruses. The antiviral activity were found to increase in the serial order iremycin less than adriamycin less than daunomycin less than alpha-rubicin I less than beta-rhodomycin I less than violamycin BI-complex by inhibition kinetic determined from Adeno virus.

[Anthracycline antibiotics from genetically modified streptomycetes. The isolation, spectroscopic structural elucidation and biologic effects of beta-rhodomycin I]. / Anthracyclinantibiotica genetisch modifizierter Streptomyceten. Zur Isolierung, spektroskopischen Strukturaufklärung und biologischen Wirkung von beta-Rhodomycin-1.

By mutagenic treatment and selection procedures the mutant ZIMET 43678 was obtained from a population of the interspecific recombinant Streptomyces violaceus subsp. iremyceticus ZIMET 43615, which showed a changed spectrum of secondary metabolites. The main component isolated from the fermentation broth was a pure anthracycline evidenced by TLC. By means of acid hydrolysis, identification of the degradation products and also by spectroscopic UV/VIS-, IR-, MS-, 1H/13C-NMR- and CD-investigations with intact anthracycline the structure 7-(alpha-L- rhodosaminyl )-beta- rhodomycinon with the absolute configuration 7S, 9R , 10R was found. The anthracycline called beta- rhodomycin -1 (1) exhibits antimicrobial and cytostatic activity in vitro and is also effective on tumour cells in tumour bearing animals.

[A new selection method for obtaining mutants of Streptomyces glaucoachromogenes producing lambdamycin using the thermophilic phage-host system Tal/Thermoactinomyces vulgaris]. / Neue Selektionsmethode zur Gewinnung von Leistungsmutanten des Lambdamycin-Bildners Streptomyces glaucoachromogenes mit Hilfe des thermophilen Phagen-Wirtssystems Tal/Thermoactinomyces vulgaris.

In order to obtain high-producing mutants of the lambdamycin producer Streptomyces glaucoachromogenes IMET 31 118, a new selection technique using the thermophilic phage-host system Tal/Thermoactinomyces vulgaris, was developed. Lambdamycin is a yellow-green pigment antibiotic of the chromoglycoside type with antimicrobial, antiviral, cancerostatic, and ergotropic activity in vitro and in vivo. The physicochemical properties of lambdamycin resemble those of chartreusin. By means of the selection technique developed the determination of the concentration-dependent influence of lambdamycin on bacterial growth inhibition and Tal-phage development in the agar diffusion sphere of mutagen-treated colonies is possible without time and material-consuming pre-tests. A positive correlation exists between the biosynthetic capacity of mutants on solid media and in fermentation liquors. Using this new selection technique, the titres of lambdamycin in fermentation liquors of mutants could be increased by 10 to 20 fold in comparison to the wild type strain.