Himalaquinones A-G, Angucyclinone-Derived Metabolites Produced by the Himalayan Isolate Streptomyces sp. PU-MM59

Himalaquinones A-G, seven new anthraquinone-derived metabolites, were obtained from the Himalayan-based Streptomyces sp. PU-MM59. The chemical structures of the new compounds were identified based on cumulative analyses of HRESIMS and NMR spectra. Himalaquinones A-F were determined to be unique anthraquinones that contained unusual C-4a 3-methylbut-3-enoic acid aromatic substitutions, while himalaquinone G was identified as a new 5,6-dihydrodiol-bearing angucyclinone. Comparative bioactivity assessment (antimicrobial, cancer cell line cytotoxicity, impact on 4E-BP1 phosphorylation, and effect on axolotl embryo tail regeneration) revealed cytotoxic landomycin and saquayamycin analogues to inhibit 4E-BP1p and inhibit regeneration. In contrast, himalaquinone G, while also cytotoxic and a regeneration inhibitor, did not affect 4E-BP1p status at the doses tested. As such, this work implicates a unique mechanism for himalaquinone G and possibly other 5,6-dihydrodiol-bearing angucyclinones.

Comprehensive study of antimicrobial susceptibility pattern and extended spectrum beta-lactamase (ESBL) prevalence in bacteria isolated from urine samples

Nowadays, increasing extended-spectrum β-lactamase (ESBL)-producing bacteria have become a global concern because of inducing resistance toward most of the antimicrobial classes and making the treatment difficult. In order to achieve an appropriate treatment option, identification of the prevalent species which generate ESBL as well as their antibiotic susceptibility pattern is essential worldwide. Hence, this study aimed to investigate the prevalence of ESBL-producing bacteria and assess their drug susceptibility in Fardis Town, Iran. A total of 21,604 urine samples collected from patients suspected to have urinary tract infection (UTI) were processed in the current study. The antimicrobial susceptibility of the isolates was tested by the disk diffusion method. The ESBL producing bacteria were determined by Double Disc Synergy Test (DDST) procedure. Bacterial growth was detected in 1408 (6.52%) cases. The most common bacterial strains causing UTI were found E. coli (72.16%), followed by K. pneumoniae (10.3%) and S. agalactiae (5.7%). Overall, 398 (28.26%) were ESBL producer. The highest ESBL production was observed in E. coli, followed by Klebsiella species. ESBL producers revealed a higher level of antibiotic resistance compared with non-ESBLs. In conclusion, ESBL production in uropathogens was relatively high. Carbapenems and Aminoglycosides were confirmed as the most effective treatment options for these bacteria.

Angucycline Glycosides from Mangrove-Derived Streptomycesdiastaticus subsp. SCSIO GJ056

Nine new angucycline glycosides designated urdamycins N1⁻N9 (1⁻9), together with two known congener urdamycins A (10) and B (11), were obtained from a mangrove-derived Streptomycesdiastaticus subsp. SCSIO GJ056. The structures of new compounds were elucidated on the basis of extensive spectroscopic data analysis. The absolute configurations of 6⁻9 were assigned by electronic circular dichroism calculation method. Urdamycins N6 (6) and N9 (9) represent the first naturally occurring (5R, 6R)-angucycline glycosides, which are diastereomers of urdamycins N7 (7) and N8 (8), respectively.

Antimicrobial Spirotetronate Metabolites from Marine-Derived Micromonospora harpali SCSIO GJ089

Two new spirotetronate aglycones, 22-dehydroxymethyl-kijanolide (1) and 8-hydroxy-22-dehydroxymethyl-kijanolide (2), along with seven new spirotetronate glycosides, microsporanates A-F (3-8) and tetrocarcin P (9), together with three known tetrocarcins [tetrocarcins A (10), B (11), and AC6H (12)], were isolated from fermentation broths of the marine-derived Micromonospora harpali SCSIO GJ089. The structures of 1-9 were elucidated on the basis of 1D and 2D NMR and MS spectroscopic data. Compounds 3-8 feature an α,β-unsaturated carbonyl moiety within their spirotetronate skeletons. Moreover, compounds 3-12 displayed strong to moderate antibacterial activities against Gram positive bacteria Bacillus thuringiensis BT01 and B. subtilis BS01 with MIC values ranging from 0.016 to 8.0 μg/mL.

[Metabolomics and molecular targeted therapy of cancer]

Metabolomics is defined as the quantitative measurement of the dynamic multiparametric metabolites. Recent technological advances in the quantification of cellular metabolites, such as capillary electrophoresis (CE) -TOFMS, have prompted the comprehensive analysis of the global metabolism. Now, metabolomics has been used in the identification of new biomarker for toxicology and disease diagnosis, and the elucidation of fermentation processes. Moreover, it is considered that metabolomics would be a powerful tool for the target identification of small molecular bioactive compounds. Here we introduce our recent study that metabolomics was applied to identify the molecular target of glucopiericidin A, which was isolated through a screening of natural products for an inhibitor of cellular filopodia protrusion in carcinoma cells.

Hydroxylation and hydrolysis: two main metabolic ways of spiramycin I in anaerobic digestion

The anaerobic degradation behaviors of five macrolides including spiramycin I, II, III, midecamycin and josamycin by sludge were investigated. Within 32days, 95% of spiramycin I, II or III was degraded, while the remove rate of midecamycin or josamycin was 75%. SPM I degradation was much higher in nutrition supplementation than that just in sludge. The degradation products and processes of spiramycin I were further characterized. Three molecules, designated P-1, P-2 and P-3 according to their order of occurrence, were obtained and purified. Structural determination was then performed by nuclear magnetic resonance and MS/MS spectra, and data indicated that hydroxylation and hydrolysis were main reactions during the anaerobic digestion of spiramycin I. P-1 is the intermediate of hydroxylation, and P-2 is the intermediate of hydrolysis. P-3 is the final product of the both reaction. This study revealed a hydroxylation and hydrolysis mechanism of macrolide in anaerobic digestion.

The co-identity of lipiarmycin A3 and tiacumicin B

The co-identity of the antibiotics lipiarmycin A3 obtained from Actinoplanes deccanensis and tiacumicin B obtained from Dactylosporangium aurantiacum was unambiguously demonstrated through a number of experimental means. Spectroscopic analyses performed on both the antibiotics themselves and on their derivatives showed no difference between the two series of compounds. Moreover, unambiguous confirmation of the postulated identity of the two compounds was achieved by chemical degradation of lipiarmycin A3 and isolation of (3S,4R)-pentane-1,3,4-triol triacetate whose relative configuration was assigned by comparison with the authentic erythro and threo pentane-1,3,4-triol triacetates, obtained by chemical synthesis.

[Molecular imprinted polymers for macrolides, aminoglycosides and some other biosynthetic antibiotics]

Molecular imprinted polymers (MIP) for macrolides, aminoglycosides and some other biosynthetic antibiotics described in the literature were analysed with a purpose of evaluating their possible use for the antibiotics sorption.

New target for inhibition of bacterial RNA polymerase: 'switch region'

A new drug target - the 'switch region' - has been identified within bacterial RNA polymerase (RNAP), the enzyme that mediates bacterial RNA synthesis. The new target serves as the binding site for compounds that inhibit bacterial RNA synthesis and kill bacteria. Since the new target is present in most bacterial species, compounds that bind to the new target are active against a broad spectrum of bacterial species. Since the new target is different from targets of other antibacterial agents, compounds that bind to the new target are not cross-resistant with other antibacterial agents. Four antibiotics that function through the new target have been identified: myxopyronin, corallopyronin, ripostatin, and lipiarmycin. This review summarizes the switch region, switch-region inhibitors, and implications for antibacterial drug discovery.

Improvement of the enediyne antitumor antibiotic C-1027 production by manipulating its biosynthetic pathway regulation in Streptomyces globisporus

The production of C-1027 in Streptomyces globisporus was previously increased 2- to 3-fold by manipulating three pathway-specific activators, SgcR1, SgcR2, and SgcR3. In this study, we have further characterized two putative C-1027 regulatory genes, sgcE1 and sgcR, by in vivo inactivation. The HxlR family DNA-binding protein SgcE1 was not essential for C-1027 biosynthesis, since inactivation of sgcE1 showed no effect on C-1027 production. In contrast, the proposed repressive role of the sgcR gene was confirmed by a 3-fold increase in C-1027 production in the ΔsgcR mutant S. globisporus SB1022 strain relative to the wild-type strain. Considering SgcR shows no significant similarity to any protein of known function, it may be representative of a new family of regulatory proteins. Finally, overexpression of the previously characterized activator sgcR1 in S. globisporus SB1022 increased the C-1027 yield to 37.5 ± 7.7 mg/L, which is about 7-fold higher than the wild-type strain.

Isolation and characterization of tirandamycins from a marine-derived Streptomyces sp

The novel dienoyl tetramic acids tirandamycin C (1) and tirandamycin D (2) with activity against vancomycin-resistant Enterococcus faecalis were isolated from the marine environmental isolate Streptomyces sp. 307-9, which also produces the previously identified compounds tirandamycins A (3) and B (4). Spectroscopic analysis of 1 and 2 indicated structural similarity to 3 and 4, with differences only in the pattern of pendant oxygenation on the bicyclic ketal system. The isolation of these putative biosynthetic intermediates was enabled by their sequestration on an adsorbent resin during early stationary-phase fermentation.

Kosinostatin, a major secondary metabolite isolated from the culture filtrate of Streptomyces violaceusniger strain HAL64

During a screening program, an actinomycete strain isolated from the Egyptian soil was investigated for its potential to show antimicrobial activity. The identification of this isolate was performed according to spore morphology and cell wall chemo-type, which suggested that this strain is a streptomycete. Further cultural, physiological characteristics and the analysis of the nucleotide sequence of the 16S rRNA gene (1480 bp) of this isolate indicated that this strain is identical to Streptomyces violaceusniger (accession number EF063682) and then designated S. violaceusniger strain HAL64. In its culture supernatant, this organism could produce one major compound strongly inhibits the growth of Gram-positive but the inhibition of Gram-negative indicator bacteria was lower. The antibiotic was separated by silica gel column chromatography and then purified on a sephadex LH-20 column and finally the purity was checked by HPLC. The chemical structure of the purified compound was determined using spectroscopic analyses (molecular formula of C33H32N2O10 and molecular weight of 617.21) and found to be identical to the kosinostatin, a quinocycline antibiotic which is known to be produced by Micromonspora sp. TP-A0468 (Igarashi et al., 2002) and to quinocycline B isolated from Streptomyces aureofaciens (Celmer et al., 1958). Although the antibiotic is known, the newly isolated strain was able to produce the antibiotic as a major product providing an important biotechnological downstream advantage.

Analysis of etimicin sulfate by liquid chromatography with pulsed amperometric detection

A new method for determination of etimicin's (ETM) purity and content is developed by liquid chromatography (LC) and pulsed amperometric detection (PAD). A reversed-phase ion-pair LC method with pulsed amperometric detection on a gold electrode after post-added NaOH is described. The mobile phase consisted of an aqueous solution containing 0.033 mol L(-1) oxalic acid, 0.012 mol L(-1) heptafluorobutyric acid, and 210 mL L(-1) acetonitrile with pH 3.40 adjusting by dilute NaOH solution. The total analysis time was not more than 30 min. The effects of the different chromatographic parameters on the separation were also investigated. A number of commercial samples of etimicin sulfate were analyzed using this method.

Antibiotic G-418, a new Micromonospora-produced aminoglycoside with activity against protozoa and helminths: fermentation, isolation, and preliminary characterization

Antibiotic G-418 is a new aminoglycoside produced as the major component by a new species of Micromonospora, M. rhodorangea NRRL 5326. The antibiotic is prepared by submerged fermentation in a soybean-dextrin medium. Antibiotic G-418 is adsorbed on a cationic-exchange resin and separated from other impurities by passing it down a Dowex (1 x 2) resin column. The antibiotic, which contains 2-deoxystreptamine, has broad-spectrum antibacterial activity and is highly active against protozoa, amoebae, tapeworm, and pinworm infections in mice. This report describes the taxonomy of the organism, and fermentation, isolation, and preliminary characterization of antibiotic G-418.

Brasilicardins B–D, new tricyclic terpernoids from actinomycete Nocardia brasiliensis

Three new tricyclic terpenoids, brasilicardins B-D (2-4), were isolated together with brasilicardin A (1), a potent immunosuppressive compound, from the cultured broth of a pathogenic actinomycete Nocardia brasiliensis IFM0406, and the structures and stereochemistry were determined by spectroscopic data and a single crystal X-ray diffraction analysis. The immunosuppressive and cytotoxic activities of 2-4 were examined in the comparison with 1.

Nikkomycin biosynthesis: formation of a 4-electron oxidation product during turnover of NikD with its physiological substrate

Nikkomycins are peptidyl nucleoside antibiotics that act as therapeutic antifungal agents in humans and easily degraded insecticides in agriculture. The nikkomycin peptidyl moiety contains a pyridyl residue derived from L-lysine. The first step in peptidyl biosynthesis is an aminotransferase-catalyzed reaction that converts L-lysine to Delta(1)- or Delta(2)-piperideine-2-carboxylate (P2C). Spectral, chromatographic, and kinetic analyses show that the aerobic reaction of nikD with P2C results in the stoichiometric formation of picolinate, accompanied by the reduction of 2 mol of oxygen to hydrogen peroxide. A high resolution HPLC method, capable of separating picolinate, nicotinate and isonicotinate, was developed and used in product identification. NikD contains 1 mol of covalently bound FAD and exists as a monomer in solution. Reductive and oxidative titrations with dithionite and potassium ferricyanide, respectively, show that FAD is the only redox-active group in nikD. Anaerobic reaction of nikD with 1 mol of P2C results in immediate reduction of enzyme-bound FAD. Because nikD is an obligate 2-electron acceptor, it is proposed that the observed 4-electron oxidation of P2C to picolinate occurs via a mechanism involving two successive nikD-catalyzed 2-electron oxidation steps. In addition to nikkomycins, a nikD-like reaction is implicated in the biosynthesis of an L-lysine-derived pyridyl moiety found in streptogramin group B antibiotics that are used as part of a last resort treatment for severe infections due to gram positive bacteria.

Development and validation of an improved method for the analysis of vancomycin by liquid chromatography selectivity of reversed-phase columns towards vancomycin components

The current method prescribed in official monographs for the purity control of vancomycin is inappropriate in that several components are not separated from each other and other components are coeluted with the main component vancomycin B. The method uses an ODS column at pH 3.2. In this study, several changes were introduced in order to improve the separation. The optimization of the separation method at low pH indicated that pH 1.7 was optimum and that the use of dioxane as organic modifier drastically improved the separation. These conditions were used to test a set of more than 40 reversed-phase columns for their selectivity towards vancomycin components. The selection of the most suitable columns was performed by means of principal component analysis. Most of these columns did not allow the separation of didechlorovancomycin from monodechlorovancomycin 1. It was found that neutral to slightly alkaline mobile phases allowed better separation. Further optimization of the separation method and a robustness study were performed by means of experimental design. This optimization indicated that pH 7.7 was optimum and gradient elution was also used to effect complete analysis. The final method uses a Kromasil column and the mobile phase comprises dioxane, water and ammonium formate solution pH 7.7. The separation of monodechlorovancomycin 2 and of some unknown impurities from the main component vancomycin B is described for the first time. The method shows good repeatability, linearity and sensitivity.

Oviedomycin, an unusual angucyclinone encoded by genes of the oleandomycin-producer Streptomyces antibioticus ATCC11891

Our investigations on the discovery of novel natural metabolites using type II polyketide synthase gene probes (actI/III) yielded an unusual angucyclinone, oviedomycin (2), when applied to the oleandomycin (1) producer Streptomyces antibioticus ATCC11891. The novel natural product was produced using S. albus R(-)M(-) as a host strain, into which a cosmid containing the oviedomycin gene cluster was transformed. Its structure was elucidated by NMR spectroscopy and mass spectrometry.

Metabolic products of microorganisms. 263. Nikkomycins SZ, SX, SoZ and SoX, new intermediates associated to the nikkomycin biosynthesis of Streptomyces tendae

New intermediates associated with nikkomycin biosynthesis, called nikkomycins SZ, SX, SoZ and SoX, were isolated and characterized from the culture broth of Streptomyces tendae Tü 901/S 2566. They are analogues to octosyl acids, shunt metabolites of polyoxin biosynthesis. The decreasing amounts of nikkomycins SZ and SX, produced in the culture medium, shows a significant correlation to the increasing amounts of the biologically active nikkomycins Z and X, dependent on the increasing concentration of iron.

Quantitative determination and separation of analogues of aminoglycoside antibiotics by high-performance liquid chromatography

Commercial bulk products and pharmaceutical drug formulations of aminoglycoside antibiotics obtained by fermentation (kanamycin, gentamicin, sisomicin and tobramycin) or by synthesis (amikacin) were analysed with high-performance liquid chromatography on a C8 reversed-phase column. The method is based on a pre-column derivatization of the aminoglycosides with a 2,4,6-trinitrobenzenesulphonic acid reagent and UV detection (350 nm). The quantitative determination was carried out vs. an external standard; both peak heights and areas were used. A gentamicin mixture was separated into five or four components, depending on the column used. Amikacin was separated from its possible regioisomers and kanamycin A was easily separated from its minor components B and C.

Inosamycin, a complex of new aminoglycoside antibiotics. I. Production, isolation and properties

A strain of Streptomyces hygroscopicus No. J296-21 (ATCC 39150) was found to produce a complex of new antibiotics, called inosamycins, which consisted of components A, B, C, D and E. They are novel aminocyclitol antibiotics structurally related to neomycin, paromomycin and ribostamycin. The antibiotic complex and each component of inosamycin exhibit a broad antibacterial spectrum but they are inactive against most of the aminoglycoside-resistant organisms. The antibacterial activity of inosamycin A, the major component of the complex, is comparable to that of neomycin but its acute toxicity is significantly lower (ca. 1/3) than that of neomycin.

Largomycin FII chromophore component 4, a new pluramycin antibiotic

The chromophore of the antitumor chromoprotein largomycin FII is a mixture of components belonging to the pluramycin class of antitumor antibiotics. Against most organisms tested, component 4 exhibited activity equal to or greater than the major chromophore components pluramycin A and deacetylpluramycin A. Data obtained from UV, IR, 1H and 13C NMR, and from fast atom bombardment mass spectrometry were used to determine the structure of component 4 as epoxykidamycin, a new member of the pluramycin class.

Improved procedure for extracting aminoglycosides from renal cortical tissue

An efficient and reproducible procedure was developed for extracting aminoglycosides from renal cortical tissue. It involves a double homogenization and two rinsings with trichloroacetic acid. A higher recovery is obtained compared with that of other previously reported methods.

Saccharocin, a new aminoglycoside antibiotic. Fermentation, isolation, characterization and structural study

A new aminoglycoside antibiotic, saccharocin has been isolated from the fermentation broth of Saccharopolyspora sp. AC-3440 (FERM P-6238) by column chromatography on a cation-exchange resin. Saccharocin is active against Gram-positive and Gram-negative bacteria. The structure was elucidated to be 4"-deamino-4"-hydroxyapramycin by 13C NMR spectral analysis.

Ravidomycin (AY-25,545), a new antitumor antibiotic

A streptomycete was isolated from a Guatemala soil sample and found to inhibit Grampositive bacteria including mycobacteria. The antibiotic-producing microorganism was characterized, identified as a new species and named Streptomyces ravidus. The antibiotic principle was extracted with organic solvent from the mycelium, isolated in crystalline form and named ravidomycin. Ravidomycin is mainly active against Gram-positive bacteria including mycobacteria. It shows only weak activity against Gram-negative organisms and no activity against fungi. Ravidomycin exhibits potent antitumor activity against P388 lymphocytic leukemia, Colon 38 tumor and CD8F1 mammary tumor. Acute toxicity in mice is low.

A new aminoglycoside antibiotic G-367 S1, 2'-N-formylsisomicin fermentation, isolation and characterization

A new aminoglycoside antibiotic, G-367 S1 (2'-N-formylsisomicin, C20H37N5O8) produced by a rare actinomycetes, Dactylosporangium thailandense G-367 (FERM-P 4840) has been isolated by column chromatography on a cation-exchange resin. G-367 S1 is active against Gram-positive and Gram-negative bacteria.

Oligostatins, new antibiotics with amylase inhibitory activity. I. Production, isolation and characterization

Oligostatins C, D and E, three new antibiotics were found in the culture filtrate of Streptomyces myxogenes nov. sp. SF-1130. Their spectral and chemical properties suggested that oligostatins were basic oligosaccharide antibiotics. They exhibited not only antibacterial activity but also strong amylase inhibitory activity.

Studies on a new aminoglycoside antibiotic, dactimicin. II. Isolation, structure and chemical degradation

A new aminoglycoside antibiotic, dactimicin produced by a Dactylosporangium matsuzakiense SF-2052 has been isolated by column chromatography on a cation-exchange resin and CM-sephadex. The structure of dactimicin was determined to be 4-amino-1,4-dideoxy-3-O-(2,6-diamino-2,3,4,6,7-pentadeoxy-beta-L-lyxo- heptopyranosyl)-1-[(N-formimidoylglycyl)-methylamino]-6-O-methyl-L-chiro-inosit ol. Alkaline hydrolysis of dactimicin afforded 1-N-(N-formylglycyl)fortimicin B, fortimicin B, fortimicin A and an acyl migration product, 2'-N-(N-formylglycyl)fortimicin B.

Reverse phase high speed liquid chromatography of antibiotics. III. Use of ultra high performance columns and ion-pairing techniques

Improved methods for the separation and quantitation of cephalosporin, penicillin, aminoglycoside and anthracycline antibiotics are presented. The use of ultra high performance 5 micrometer phase columns combined with the added dimension of ion-pairing greatly increases the ease of separation and speed of analysis of complex antibiotic mixtures. Antibiotics in a variety of dosage forms and in fermentation broths have been examined in order to provide the maximum data on impurities to meet regulatory requirements for drug safety, purity and efficacy. Mixtures of antibiotics have been analyzed to demonstrate the improved separations, increased efficiency and shortened analysis times possible with ultra thin performance columns. Under these improved conditions, the danger of multiple components in a single peak are markedly reduced.

[Comparative characteristics of the methods for assessing aminoglycoside extraction with the artificial kidney tobramycin clearance and dialyzability]

The pharmacokinetics of tobramycin after its intravenous or intramuscular injection in a dose of 80 mg for 60 minutes was studied in 8 patients with chronic glomerulonephritis in the terminal stage of chronic renal insufficiency. The drug levels wee determined in the arterial (CA) and venous (CV) blood and dialyzates (CD) during the hemodialysis (6 hours) and 13-70 hours before the hemodialysis. The antibiotic was administered simultaneously with connection of the "artificial kidney" apparatus (KIIL) or 1 hour after it. The values of the clearance (CID) and dialyzing (D) of tobramycin were calculated with the following equations: (CID)1 equals Q(CA minus CV)/CA; (CID)4 equals FCD/CA; (D)2 equals Q(CA minus CV)/(CA minus CD); (D)5 equals FCD/(CA minus CD), where Q and F are the rates of the blood and dialysate flow respectively. In all cases the values of CID and D correlated and the difference between them was not significant. During the hemodialysis the values of (CID)1 varied to a greater extent than those of (CID)4. Irrespective of the procedure for estimation of CID the above variation was not pronounced, when tobramycin was administered simultaneously with initiation of the hemodialysis or during it than long before connection of the "artificial kidney" apparatus. In this connection it is recommended that antibiotic extraction be characterized by determination of (CID)4 on the drug administration long before the initiation of the hemodialysis. When Q equals 200 ml/min and F equals 600 ml/min, the average value of CLD for tobramycin was equal to 64 ml/min and the extraction coefficient was equal to 35 per cent.

Microbial products. IV. X-14847, a new aminoglycoside from Micromonospora echinospora

Micromonospora echinospora strain X-14847 produces gentamicin A as the major antibiotic together with a new aminoglycoside, termed X-14847, and identified as a 2-amino-2-deoxy-alpha-D-glucopyranosyl myo-inositol. This report describes the taxonomy of the culture, fermentation conditions, the isolation and the identification of X-14847.

A new aminoglycoside antibiotic, sannamycin C and its 4-N-glycyl derivative

Streptomyces sannanensis KC-7038 used for the production of sannamycins A and B has also produced another antibiotic sannamycin C, in the culture broth. Physico-chemical characterization revealed that sannamycin C is a new aminoglycoside antibiotic having 6-N-methylpurpurosamine C and 2-deoxy-3-epi-fortamine. Its 4-N-glycyl derivative indicated inhibitory activity against Gram-positive and Gram-negative bacteria containing aminoglycoside resistant strains.

A new broad-spectrum aminoglycoside antibiotic complex, sporaricin. I. Fermentation, isolation and characterization

Two new aminoglycoside antibiotics, sporaricins A (C17H35N5O5) and B (C15H32N4O4) produced by a rare actinomycetales, Saccharopolyspora hirsuta subsp. kobensis have been isolated by column chromatography on a cation-exchange resin. Sporaricin A is highly active against Gram-positive and Gram-negative bacteria including aminoglycoside-resistant strains.

The structure of aminoglycoside antibiotic 66-40G produced by Micromonospora inyoensis

Aminoglycoside antibiotic 66-40G is a minor component produced in the fermentation of Micromonospora inyoensis. Its structure has been established as 3''-de-N-methyl-sisomicin (4) by spectroscopic means and by direct comparison with an authentic sample obtained from photochemical oxidative de-N-methylation of sisomicin (1).

Fortimicins A and B, new aminoglycoside antibiotics. II. Isolation, physico-chemical and chromatographic properties

The aminoglycoside antibiotics fortimicins A and B produced by a naturally occurring strain Micromonospora sp. MK-70 were isolated from its fermentation beer. Fortimicins A and B were isolated as water-soluble, basic, white amorphous powders having molecular formula C17H35N5O6 and C15H32N4O5, respectively. Acid hydrolysis of fortimicin A indicated that it has one mole of glycine in its molecule while fortimicin B has not. Paper chromatography, silica-gel and carbon thin-layer chromatography revealed that fortimicins A and B are novel aminoglycoside antibiotics.

Use of electrophoresis in the identification and quantitation of antibiotics administered in combinations

The investigation presents a method of electrophoretic separation of antibacterial drugs which are used in combinations in clinical medicine. Subsequent to electrophoresis in agarose gel, a microbiological assay was performed. This technique permitted the determination of the concentrations of beta-lactam antibiotics, rifampicin, and clindamycin in the presence of aminoglycosides. In therapeutic combinations of fusidic acid and clindamycin, the concentrations of each drug could be determined.