Metabolic products of microorganisms. 261. Obscurolides, a novel class of phosphodiesterase inhibitors from streptomyces. I. Production, isolation, structural elucidation and biological activity of obscurolides A1 to A4.

A novel class of butyrolactones, named obscurolides, was isolated from the culture filtrate of Streptomyces viridochromogenes by chemical screening methods. The structural elucidation of the obscurolides A1 to A4 (1 approximately 4) is described. The carboxy group of the 4-aminobenzoic acid moiety of obscurolide A1 (1) is reduced in the other compounds. The isolated natural products have been proved to be diastereomeric mixtures by a partial racemization at C-7 which belongs to an allylic alcohol system. The obscurolides showed a weak inhibitory activity against calcium/calmodulin-dependent and independent phosphodiesterases from bovine.

Metabolic products of microorganisms. 244. Colabomycins, new antibiotics of the manumycin group from Streptomyces griseoflavus. I. Isolation, characterization and biological properties.

The yellow colabomycins A to C, three new antibiotics of the manumycin group produced by Streptomyces griseoflavus (strain Tü 2880), were detected by chemical screening. They were isolated from mycelium extracts by column chromatography on various adsorbents, followed by preparative reversed phase HPLC. The main compound, colabomycin A (1), was characterized and shown to be chiefly biologically active against Gram-positive bacteria and stem cells of murine L1210 leukemia.

Immunosuppressive effects of the macrolide antibiotic bafilomycin towards lymphocytes and lymphoid cell lines.

The effects of bafilomycin macrolide antibiotics on primary lymphocytes and on tumor cell lines were investigated. Bafilomycin A markedly suppressed DNA, RNA, and protein synthesis in splenocyte cultures of several inbred mouse strains. Bafilomycins were also inhibitory towards cultures of concanavalin A- or lipopolysaccharide-activated murine spleen cells, and inhibited the mitogen-induced differentiation of B lymphocytes into immunoglobulin-secreting plasma cells. Corresponding results were obtained in human cell cultures. A hydrolysis product of the bafilomycin molecule was inactive. Bafilomycin also inhibited the growth of various lymphoid cell lines, the B cell line BCL1, the macrophage cell lines J774 and P338D1, and the T cell line EL4. The sensitivity of the tumor cell lines increased when, simultaneously with bafilomycin, mitogens were applied to the cell cultures. The immunosuppressive action of cyclosporin A could be enhanced by bafilomycin, which could be of importance for the elucidation of the molecular mechanism of T cell suppression, and for applied medical research.

Metabolic products of microorganisms. 239. Bacimethrin isolated from Streptomyces albus identification, derivatives, synthesis and biological properties.

Bacimethrin (1), known as a thiamine antagonist produced by Bacillus megatherium, was isolated from Streptomyces albus and has been further characterized by NMR spectra and acetylation. A new easy three step synthesis for 1 is described. The biological activity of 1, and its mode of action were discussed. There are indications that bacimethrin inhibits the phosphorylation of 4-amino-5-hydroxymethyl-2-methylpyrimidine (Pyr-OH) during thiamine biosynthesis.

Metabolic products of microorganisms. 234. Urdamycins, new angucycline antibiotics from Streptomyces fradiae. I. Isolation, characterization and biological properties.

The colored urdamycins A to F, six new angucycline antibiotics produced by Streptomyces fradiae strain Tü 2717, were detected by chemical screening. They are biologically active against Gram-positive bacteria and stem cells of murine L1210 leukemia. The urdamycins are glycosides and differ in their aglycones, which can be liberated by acidic hydrolysis besides the sugars D-olivose and L-rhodinose. The structure of the main compound, urdamycin A, follows from the spectroscopic and chemical data in connection with an X-ray analysis. The aglycone urdamycinone A is identical with aquayamycin. The structures of urdamycin B, E, F and partial structures of urdamycin C and D, will be presented in a subsequent paper. The new term "angucycline/angucyclinone" is used for an increasing group of related antibiotics.

Metabolic products of microorganisms. 225. Elloramycin, a new anthracycline-like antibiotic from Streptomyces olivaceus. Isolation, characterization, structure and biological properties.

Elloramycin (1), a new antibiotic produced by Streptomyces olivaceus strain Tü 2353, was detected by chemical screening. The dark yellow compound, molecular formula C32H36O15, is weakly active against a variety of Gram-positive bacteria, especially streptomycetes and against stem cells of L-1210 leukemia. Acidic hydrolysis of the antibiotic liberated elloramycinone (3) as aglycone and 2,3,4-tri-O-methyl-L-rhamnose, which was identified as methyl glycoside 5b. The structure of elloramycin was established by comparison of the spectra (UV, 1H NMR, 13C NMR) with those of the known tetracenomycin C (2), 3 and the fact that 2 and 3 gave the same tetramethyl ether after permethylation. Elloramycin is an anthracycline-like antibiotic, the aglycone resembles tetracenomycin C, the sugar is connected in a phenolic alpha-glycosidic linkage.

Metabolic products of microorganisms. 224. Bafilomycins, a new group of macrolide antibiotics. Production, isolation, chemical structure and biological activity.

The bafilomycins A1, A2, B1, B2, C1 and C2, a new type of macrolide antibiotics with a 16-membered lactone ring, were isolated from the fermentation broth of three Streptomyces griseus strains (TU 1922, TU 2437, TU 2599) by ethyl acetate extraction and column chromatography on silica gel. The bafilomycins exhibit activity against Gram-positive bacteria and fungi. Physico-chemical data, chemical structures and biological activities are reported.

Mitogenic and suppressive activity of mycelia from gram-positive bacteria on murine and human lymphocytes.

Mycelia from several strains of Streptomyces were potent B-lymphocyte mitogens for spleen cells from 3 inbred mouse strains (BALB/c, C3H/HeJ, C3H/nu/nu), inducing lymphocyte proliferation and differentiation into immunoglobulin-secreting cells. Streptomyces mycelia were also mitogenic towards human peripheral blood lymphocytes, where maximal stimulation was found on days 5 to 7. On the other hand, human lymphocytes incubated with the mycelia for 3 days, but not the supernatants of these cultures, strongly inhibited mixed leukocyte reactions. Irradiation experiments suggest the induction of both radioresistant and radiolabile suppressor-cell populations by the components.

[Metabolic products of microorganisms, 149. Lysolipin I, a new antibiotic from streptomyces violaceoniger (author's transl)]. / Stoffwechselprodukte von Mikroorganismen 149. Mitteilung. Lysolipin I, ein neues Antibioticum aus Streptomyces violaceoniger

From the cultures of Streptomyces violaceoniger, strain Tü 96, two new lipophilic antibiotics, Lysolipin I and Lysolipin X were isolated. The latter one is chemically unstable and is easily transformed to Lysolipin I. The deeply yellow Lysolipin I has a molecular formula C29H24CINO11. It was characterized by the ir, uv, H-nmr and 13C-nmr spectra, which make a quinone structure very probable. Lysolipin I is active against Gram-positive and Gram-negative bacteria. However, enterobacteriae are only inhibited in high dilution, when the membrane permeation is damaged. Lysolipin I acts lytically against bacterial cells. Its activity is decreased by several lipids. The site of action is the biosynthesis of bacterial cell walls, an interaction with the carrier lipid for mureine intermediates being probable.