H. Zähner

Bio: H. Zähner is an academic researcher from Ciba Specialty Chemicals. The author has contributed to research in topics: Boromycin & Echinomycin. The author has an hindex of 16, co-authored 18 publications receiving 866 citations.

Stoffwechselprodukte von Actinomyceten. 26. Mitteilung. Über die Isolierung und Charakterisierung der Ferrioxamine A—F, neuer Wuchsstoffe der Sideramin‐Gruppe

Abstract: Isolation and properties of the ferrioxamines A, B, C, D1, D2, E and F, iron containing growth factors belonging to the group of the sideramines, are described.

Stoffwechselprodukte von Mikroorganismen. 57. Mitteilung. Boromycin

Abstract: A new strain of Streptomyces antibioticus (WAKSMANet WOODRUFF), ETH 28829, produces a novel antibiotic, boromycin, which appears to be the first well defined boron containing organic compound to have been found in nature. Boromycin is a complex of boric acid with a tetradentate organic complexing agent, that yields by hydrolysis D-valine, boric acid, and a polyhydroxy compound of macrolide type.

Stoffwechselprodukte von Actinomyceten. 3. Mitteilung. Nonactin

Abstract: Aus Kulturfiltrat und Mycel eines Streptomyces viridochromogenes oder Streptomyces olivochromogenes nahestehenden Streptomyceten wurde neben Actidion eine neutrale, farblose, kristalline Verbindung C30H48O9, das Nonactin, isoliert, die chemisch wenig reaktiv ist und gegenuber den untersuchten Mikroorganismen unwirksam oder nur schwach wirksam war.

Zur Systematik der Actinomyceten

Abstract: The macrolide-antibiotics are discussed in respect to their chemistry and biology. The single substances are listed. An investigation and classification of the streptomycetes producing macrolides, is added; the single species are critically revised. Relations are established between the producers and their products.

Stoffwechselprodukte von Actinomyceten. 7. Mitteilung. Echinomycin

Abstract: Aus den Kulturbruhen von Streptomyces echinatus n. sp. wurde ein neues lipophiles, neutrales Antibioticum – das Echinomycin, C29H37O7N7S – isoliert und durch analytische Daten, UV.- und IR.- Absorptionsspektrum, sowie biologische Wirksamkeit charakterisiert.

Natural Products as Sources of New Drugs from 1981 to 2014

Abstract: This contribution is a completely updated and expanded version of the four prior analogous reviews that were published in this journal in 1997, 2003, 2007, and 2012. In the case of all approved therapeutic agents, the time frame has been extended to cover the 34 years from January 1, 1981, to December 31, 2014, for all diseases worldwide, and from 1950 (earliest so far identified) to December 2014 for all approved antitumor drugs worldwide. As mentioned in the 2012 review, we have continued to utilize our secondary subdivision of a “natural product mimic”, or “NM”, to join the original primary divisions and the designation “natural product botanical”, or “NB”, to cover those botanical “defined mixtures” now recognized as drug entities by the U.S. FDA (and similar organizations). From the data presented in this review, the utilization of natural products and/or their novel structures, in order to discover and develop the final drug entity, is still alive and well. For example, in the area of cancer, over t...

The biochemistry of desferrioxamine and its relation to iron metabolism.

Abstract: For several years now, the metabolites of Actinomycetes have been under study in the research laboratories of the Swiss Federal Institute of Technology in Zurich and of CIBA Limited in Basle. In the course of these studies, numerous compounds have been isolated which contain complexbound trivalent iron and which are brownish-red in color. By reference to the effects they exert, these naturally occurring substances can be subdivided into two groups : the sideromycins and the sideramines.' The sideromycins are antibiotics, whereas the sideramines specifically antagonize the antibacterial properties of the sideromycins. The sideramines also possess growth-promoting properties and appear to exert an important function in the iron metabolism of microorganisms, possibly acting as iron donors in the incorporation of iron in the porphyrin systems. Among the various sideramines obtained from Streptomyces pilosus, the principal product is the so-called ferrioxamine B.?.$ The complex-bound trivalent iron contained in ferrioxamine B can be removed by chemical means, thus yielding the colorless, crystalline substance to be discussed here: desferrioxamine B.' Desferrioxamine is composed of one molecule of acetic acid, two molecules of succinic acid, and three molecules of 1-amino-5-hydroxylaminopentane. The organic units of which desferrioxamine is built up are interlinked to form a chain, in which there are three hydroxamic acid groups inside, and one free amino group a t the end. The free amino group accounts for the basic character of the compound, which enables i t to form salts with organic and inorganic acids (FIGURE 1). When a ferric ion comes into contact with desferrioxamine, the straightchained molecule twines itself around the ion, becoming attached to the latter by means of its three hydroxamic acid groups (FIGURE 2 ) . The iron is thus surrounded by a shell of organic material, which results in an iron complex of very great stability. The stability constants for various desferrioxamine-metal complexes compared with the constants for other chelating agents are listed in TABLE l.596 The higher the constant, the more stable the complex. The highest figure here, lo:{', is for the iron complex of desferrioxamine. All the other constants for this compound are lower by at least 10.' This means that desferrioxamine is not only the most potent, but also by far the most spe-

Base Specificity in the Interaction of Polynucleotides with Antibiotic Drugs

Abstract: Echinomycin, daunomycin, ethidium bromide, nogalamycin, chromomycin, mithramycin, and olivomycin inhibit RNA synthesis by RNA polymerase by interacting with the DNA template. Chromomycin and olivomycin form complexes with DNA, preferably in the helical form, but not with RNA. These complexes require guanine in DNA and the addition of a stoichiometric amount of bivalent cation. None of the other antibiotics requires the presence of any single base in the template for its action.