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PubMed1987

The influence of yeast growth phase in vivo on the efficacy of topical polyenes.

We compared the efficacy of two polyenes, amphotericin B and natamycin, in two models of yeast infection. In one, treatment was begun immediately after inoculation, in the other it was delayed 24 hours. In each model infection with Candida albicans was established in the corneal stroma of dutch-belted rabbits and treated topically with 5% natamycin or amphotericin B 0.15% and 0.075%. Quantitative isolate recovery techniques were used to assess response after 5 days of treatment. A significant therapeutic effect was present for amphotericin B in both models. However, delayed treatment with natamycin was ineffective using treatment schedules efficacious when begun 1 hour after inoculation. A therapeutic effect was present only with administration of the drug every 1/2 hr. This altered response may reflect a difference in susceptibility between different growth phases in yeasts.

Administration, Topical↗
PubMed1977

Polyene antibiotics. VIII. The structure of rimocidin.

A structure is assigned to the tetraene antibiotic rimocidin, based in part on 13C NMR spectroscopy and field desorption mass spectrometry. The structure assigned revises a structure proposed in 1966 which was anomalous in relation to those of other polyene antibiotics.

Anti-Bacterial Agents↗
PubMed1979

Hydroheptin: a water-soluble polyene macrolide. II. Chemical and biological properties.

Hydroheptin, a new polyene macrolide antifungal antibiotic, is co-produced with the antibiotic, chartreusin, by a strain of Streptomyces chartreusis designated as IMRU 3962 isolated in our laboratory. The unique water-solubility of this antibiotic at neutrality, revealing in aqueous solution molecular dispersion and an ultraviolet-visible absorption spectrum characteristic of an all-trans heptaene chromophore, clearly distinguishes it from all previously-described and naturally-occurring heptaene macrolides. The isolation and identification of the amino sugar, mycosamine (3-amino-3,6-dideoxy-D-mannose), in acid hydrolysates of hydroheptin and the absence of an aromatic amine upon retrograde alkaline dealdolization of the molecule certainly characterize the antibiotic as a member of the non-aromatic heptaene macrolide group. Chromatographic and countercurrent distribution studies likewise support its novelty. With little or no demonstrable activity against bacteria, hydroheptin as compared to other non-aromatic heptaene macrolides exhibits excellent but somewhat less activity against a wide variety of yeasts and fungi. Likewise, its parenteral toxicity appears to be less than that of other heptaene macrolides.

Animals↗
PubMed1979

Studies on the competition of polyene antibiotics for sterols.

The fractional change in the corrected fluorescence of pimaricin or filipin in the presence of a limiting amount of sterol and a competing polyene antibiotic has been used to estimate the relative affinity of amphotericin B, nystatin, filipin, and pimaricin for stigmasterol and for cholesterol. The relative affinities for cholesterol were filipin greater than amphotericin B greater than pimaricin greater than nystatin, while the relative affinities for stigmasterol were filipin greater than pimaricin greater than amphotericin B greater than nystatin. The data indicate that pimaricin and filipin can both interact simultaneously with about 30% of the cholesterol or stigmasterol. However, the stoichiometry of filipin and pimaricin alone for cholesterol and for stigmasterol in dilute aqueous solutions is 1 : 1. In the experiments which indicated both pimaricin and filipin interact with the same sterol molecule changes in corrected fluorescence and the absorbance spectra were monitored; and these criteria indicated that both pimaricin and filipin had interacted with the sterols. Light-scattering measurements indicate large aggregates were not formed. Although the data shows in dilute aqueous solutions the stoichiometry of filipin and/or pimaricin for sterols is 1 : 1, in more complex solutions, other combinations or interactions are indicated especially for pimaricin.

Amphotericin B↗
PubMed1982

Physicochemical and biological comparison of polyene macrolide antibiotics fungichromin, lagosin and cogomycin.

The three polyene macrolide antibiotics, fungichromin, lagosin, and cogomycin, previously described as having some stereochemical differences at one or more centers, are shown by countercurrent distribution, high-performance liquid chromatography, carbon-13 nuclear magnetic resonance spectroscopy, circular dichroism, and biological studies to be identical in all respects, including stereochemical aspects. The differences observed earlier in their properties have now been ascribed to varying amounts of impurities, which are separable by high-performance liquid chromatography. All three antibiotics contain one major and several minor components.

Antibiotics, Antineoplastic↗
PubMed1983

Tetrafungin, a new polyene macrolide antibiotic. I. Fermentation, isolation, characterization, and biological properties.

A new polyene macrolide antifungal antibiotic, named tetrafungin, was isolated from the cultured mycelium of a Streptomyces strain. Fermentation, isolation, physico-chemical and biological properties of the antibiotic are described. Its UV absorption spectrum and its physico-chemical characteristics place this antibiotic in the group 2.2.2.3 of the Berdy classification.

Anti-Bacterial Agents↗
PubMed1983

Tetrafungin, a new polyene macrolide antibiotic. II. Taxonomy of the producing organism and comparison with nystatin by means of high performance liquid chromatography.

Tetrafungin, a new polyene macrolide antibiotic, is produced by a Streptomyces strain identified as a new subspecies of Streptomyces albulus and named Streptomyces albulus subsp. tetrafungini. Tetrafungin and nystatin have been investigated and compared by HPLC. It has been demonstrated that tetrafungin and nystatin differ qualitatively in, at least, one component, and quantitatively in their relative amounts of common components.

Anti-Bacterial Agents↗
PubMed1989

The structure of vacidin A, an aromatic heptaene macrolide antibiotic. I. Complete assignment of the 1H NMR spectrum and geometry of the polyene chromophore.

The constitution of vacidin A, a representative of the aromatic heptaene macrolide antibiotics was established on the basis of 13C and 1H-1H double quantum filtered correlated spectroscopy, rotating frame nuclear Overhauser effect spectroscopy, J-resolved 1H as well as 1H-13C correlation NMR spectra. Geometry of the polyene chromophore was determined as 22E,24E,26E,28Z,30Z,32E,34E.

Anti-Bacterial Agents↗
PubMed1992

New polyenic antibiotics active against gram-positive and gram-negative bacteria. VIII. Construction of synthetic medium for production of mono-chloro-congeners of enacyloxins.

New antibiotics enacyloxins (ENXs) are a family of non-lactonic polyene antibiotics produced by Frateuria sp. W-315. For the production of antibiotics, we had to employ two-step fermentations, the first is the production of spent medium of Neurospora crassa and the second is the production of antibiotics by Frateuria. To simplify the production of antibiotics, systematic analyses have been done on the spent medium, and factors which affect the production of antibiotics characterized. From the above results, we constructed a new medium for antibiotic production. Moreover, we could get a new antibiotic named enacyloxin IIIa (1), C33H48O11NCl (m/z 669). 1 was deduced to be one of the congeners of enacyloxins because it was similar to ENX IIa or ENX IVa both in biological and physico-chemical properties. Chlorine of 1 could be replaced by bromine, biosynthetically, and the resultant bromine-containing antibiotic also showed an antibacterial activity comparable to 1.

Acetobacteraceae↗
PubMed1993

AB023, novel polyene antibiotics. II. Isolation and structure determination.

AB023, a complex of new polyene antibiotics, was isolated from a soil Streptomyces strain. The two main components, pentaene antibiotics AB023a and AB023b, were separated and purified by preparative chromatographic methods and their structures were determined by extensive NMR and mass spectrometric studies.

Antifungal Agents↗
PubMed1976

Antimycotic activity in vitro and in vivo of a new hydrosoluble polyene antibiotic.

The in vitro and in vivo activity of a new water soluble polyene antibiotic, anmed SPA-S-222, has been studied on numerous Candida and Cryptococcus species. The in vitro tests were carried out in comparison with nystatin and amphotericin B whose antimycotic properties are already well known. The inhibition of "germination" of various strains of Candida albicans was also investigated. The results show that SPA-S-222 has greater antimycotic activity than nystatin or amphotericin B. Tests on the protection afforded by SPA-S-222 in Swiss albino mice infected with C, albicans were satisfactory as regards both the total protective dose and the partial protective dose (P.D. 50%).

Amphotericin B↗
PubMed1975

Studies on the mechanism of action of calciferol. VIII. The effects of dietary vitamin D and the polyene antibiotic, filipin, in vitro, on the intestinal cellular uptake of calcium.

Intestinal transport and cellular uptake of calcium were studied in vitro in ileal segments obtained from calciferol (vitamin D)-deficient (minus D3) chicks or in calciferol-treated chicks (+ D3). When calcium flux (J) was measured in both the mucosal yields serosal (J-ms) and serosal yields mucosal (J-sm) directions it was found that calcium transport in the +D3 system was an active process. Calcium was not actively transported in the minus D3 system or by either the +D3 or minus D3 serosal tissues which underlie the intestinal mucosa tissue. It was also found that the serosal tissue was not the rate-limiting step in calcium translocation. When calcium uptake was measured at the mucosal or brush border surface it was found to be a cation-oriented, saturable process in both the +D3 and minus D3 systems and was enhanced by calciferol supplementation. The rate of uptake was found to exhibit a two component transport phenomenon, one a saturable process at low Ca2+ concentrations and the other a linear of diffusion process at higher Ca2+ concentrations (greater than 5 mM). The polyene antibiotic, filipin, was used to study the transport and uptake of calcium in both the +D and minusD chick ileum in vitro. Filipin (10 mug/ml), when added in vitro to solutions bathing the mucosal surface of the ileum, stimulated the calcium flux, J-ms, of minus D ileal tissue by 150 to 200%, but had little or no stimulatory effect on J-ms of +D3 ileal tissue. However, in contrast it stimulated calcium uptake across the mucosal membrane in both the +D3 and minus D3 ileal tissue (50 to 100%). The effect of filipin is specific for calcium uptake as compared to Rb+, P-i, SO4(2-), glycerol, thiourea, and urea uptake. Isolated brush borders from +D3 chicks were found to bind calcium to a greater extent than the minus D3 brush borders, but both membrane fractions had the same cholesterol content. The sum of this and other evidence suggests that of uptake of calcium is a calciferol-mediated event which is not the rate-limiting step in the total transport of this ion across the intestinal epithelial cell. The filipin effect appears to affect a structural reorganization of the brush border membrane in both the +D3 and minus D3 membranes in a manner specific for calcium translocation. It now appears that filipin treatment somehow makes both transport systems more efficient in the uptake of calcium, but in a manner independent of the mode of action of calciferol. However, these data suggest that other components associated with calcium uptake are calciferol-dependent in an as yet unknown fashion.

Animals↗
PubMed2000

Therapeutic efficacy of hamycin, a polyene antimycotic agent, for experimental cutaneous candidiasis in guinea pigs.

The therapeutic efficacy of 1% cream and 1% solution of hamycin, a polyene antimycotic agent, in the model of cutaneous candidiasis in prednisolone-treated guinea pigs was evaluated in comparison with that of comparable formulations of miconazole. Each preparation was topically applied once a day for three consecutive days starting on the fifth day post infection, and quantitative culture study was conducted on the ninth day post infection. Both formulations were much more highly effective in terms of eradication of fungi like miconazole formulations.

Administration, Topical↗
PubMed2002

The mechanism of the hemolytic activity of polyene antibiotics.

The kinetics of the filipin-, amphotericin B- and nystatin-induced hemolysis of human erythrocytes were investigated. Filipin-induced hemolysis is of the damage type. It is an all-or-none process, partly inhibited by Ca2+ or Ba2+ but not by Mg2+, Na+ or SO42-. The hemolytic activity of filipin is explained by the formation of large aggregates within the erythrocyte membrane in the form of large perforations, permeable to substances of low molecular weight as well as to macromolecules, including hemoglobin. In isotonic KCl solution, both amphotericin B and nystatin, at low concentrations, form smaller aggregates within the membranes. As a result, the permeability of the membranes to KCl increases and hemolysis occurs. However, the kinetics of the hemolysis induced by the two polyenes is complex. The process shows some features of the permeability type and some of the damage type. It is suggested that amphotericin B and nystatin may simultaneously form a number of transport systems, differing in their molecular organisation and hemolytic activity. Their participation in erythrocyte membrane permeability can be modified by small changes in membrane organisation and the chemical composition of the incubation medium. In isotonic solutions of divalent cation chlorides, and at higher antibiotic concentration, additional aggregates, allowing divalent cations to permeate, appear. These structures do not permit SO4(2-) to permeate.

Amphotericin B↗
PubMedDate not supplied

[The sensitivity of yeasts from the Candida genus isolated from cancer patients to polyene antifungals].

Candida strains susceptibility from cancer patients were compared with Candida strains susceptibility from patients, without cancer by MIC (minimal inhibitory concentration) and MFC (minimal fungicidal concentration) to Amphotericin B and Nystatin. Broth dilution method and agar dilution method were the procedure employed. The authors find no significant differences between the studied groups. The problem of Candida resistance to polyene antifungals is discussed.

Amphotericin B↗
PubMed2005

Molecular modelling of membrane activity of amphotericin B, a polyene macrolide antifungal antibiotic.

Amphotericin B (AmB) is a well known polyene macrolide antibiotic used to treat systemic fungal infections. Despite its toxicity AmB is still regarded as a life-saving drug. The lack of adequate knowledge of the AmB mechanism of action is a serious obstacle to efficient development of new less toxic derivatives. Complementary to various experimental approaches, computational chemistry methods were used to study AmB mechanism of action. A programme lasting for a decade, that was run by our group covered studies of: i) molecular properties of AmB and its membrane targets, ii) structure and properties of AmB membrane channels, and iii) interaction of AmB with the membrane.

Algorithms↗