Antimicrobial activity of <Emphasis Type="Italic">Bacillus megaterium</Emphasis> strains

A bacterial strain with a high level of antimicrobial activity was isolated from soil and identified as Bacillus megaterium. Production of antibiotics by nine strains of this species from the collection of the State Research Institute for Genetics and Selection of Industrial Microorganisms was investigated. In submerged cultures, nine out of ten B. megaterium strains were found to produce antibacterial antibiotics differing in their spectra of action. Physicochemical characteristics of five compounds were described. Three of them belonged to peptide antibiotics. All five compounds were active against the methicillin-resistant strain Staphylococcus aureus INA 00761. Three of them were shown to be the previously undescribed compounds. Antibiotics produced by various B. megaterium strains were also active against the Leuconostoc mesenteroides VKPM B-4177 strain resistant to glycopeptide antibiotics and against gram-negative bacteria Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922.     

Triterpenoids from the Stem Bark of Melia toosendan and Determination of Their Absolute Configurations at C(24)

Six new triterpenoids, meliasenins S–X ( 1 – 6 , resp.), were isolated from the stem bark of Melia toosendan. Their structures were elucidated by mass spectrometry, NMR experiments, and comparison with the known compounds. Particularly, the absolute configuration at C(24) in new compounds was determined through their CD spectra of the [Pr(FOD)₃] complex (fod=1,1,1,2,2,3,3,7,7,7‐decafluoroheptane‐4,6‐dione) in CCl₄, as well as by using Mosher's method.     

Synthesis of the Deuterated Sex Pheromone Components of the Grape Borer,Xylotrechus pyrrhoderus

Adult males of the grape borer, Xylotrechus pyrrhoderus, secrete (S)-2-hydroxy-3-octanone [(S)-1] and (2S,3S)-2,3-octanediol [(2S,3S)-2] from their nota of prothoraces as sex pheromone components. Their structural similarity suggests that one of them is the biosynthetic precursor of the other component. In order to confirm the biochemical conversion, deuterated derivatives of both components were synthesized by starting from a Wittig reaction between hexanal and an ylide derived from D₅-iodoethane and ending with enantiomeric resolution by chiral HPLC. The molecular ions of 1 and 2 could scarcely be detected by using a GC-MS analysis, and the labeled compounds showed similar mass spectra to the unlabeled pheromone components. However, several fragment ions, including four deuterium atoms, were observed in the mass spectra of their acetate derivatives, indicating that the conversion could be confirmed by examining a compound with the diagnostic ions after acetylation of the volatiles collected from insects treated with the labeled precursors.     

Purification and characterization of antibacterial substances produced by a marine bacterium Pseudoalteromonas haloplanktis strain

Aims: To purify and characterize compounds with antimicrobial activity from Pseudoalteromonas haloplanktis inhibition (INH) strain. Methods and Results: The P. haloplanktis isolated from a scallop hatchery was used to analyse antibacterial activities. Crude extracts were obtained with ethyl acetate of the cultured broth, after separation of bacterial cells, and assays against six strains of marine bacteria and nine clinically important pathogenic bacteria. The active compounds were purified from ethyl acetate extracts, by a combination of SiO₂ column and thin layer chromatography. Two active fractions were isolated, and chemical structures of two products from the major one were unambiguously identified as isovaleric acid (3-methylbutanoic acid) and 2-methylbutyric acid (2-methylbutanoic acid), by comparing their mass spectra and ¹H- and ¹³C-nuclear magnetic resonance spectra to those of authentic compounds. Conclusions: In the antibacterial activity of P. haloplanktis INH strain, extra cell compounds are involucred, mainly isovaleric and 2-methylbutyric acids. Significance and Impact of the Study: Production of antimicrobial compounds by marine micro-organisms has been widely reported; however, the efforts not always are conducted to purification and applications of these active compounds. This study is a significant contribution to the knowledge of compounds unique from marine bacteria as potential sources of new drugs in the pharmacological industry.     

Advanced online monitoring of cell culture off‐gas using proton transfer reaction mass spectrometry

Mass spectrometry has been frequently applied to monitor the O₂ and CO₂ content in the off‐gas of animal cell culture fermentations. In contrast to classical mass spectrometry the proton transfer reaction mass spectrometry (PTR‐MS) provides additional information of volatile organic compounds by application of a soft ionization technology. Hence, the spectra show less fragments and can more accurately assigned to particular compounds. In order to discriminate between compounds of non‐metabolic and metabolic origin cell free experiments and fed‐batch cultivations with a recombinant CHO cell line were conducted. As a result, in total eight volatiles showing high relevance to individual cultivation or cultivation conditions could be identified. Among the detected compounds methanethiol, with a mass‐to‐charge ratio of 49, qualifies as a key candidate in process monitoring due to its strong connectivity to lactate formation. Moreover, the versatile and complex data sets acquired by PTR MS provide a valuable resource for statistical modeling to predict non direct measurable parameters. Hence, partial least square regression was applied to the complete spectra of volatiles measured and important cell culture parameters such as viable cell density estimated (R² = 0.86). As a whole, the results of this study clearly show that PTR‐MS provides a powerful tool to improve bioprocess‐monitoring for mammalian cell culture. Thus, specific volatiles emitted by cells and measured online by the PTR‐MS and complex variables gained through statistical modeling will contribute to a deeper process understanding in the future and open promising perspectives to bioprocess control. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:496–504, 2014     

Additional phytoalexin-like compounds in Ht-gene resistance of corn to Helminthosporium turcicum

Four additional compounds inhibitory to germination of Helminthosporium turcicum spores were isolated from lesion-extracts of field-grown Ht-gene corn (Zea mays) lines which were inoculated with H. turcicum. The compounds were named phytoalexins A₃, A_4-I, A_4-II and A₅. A₃, A_4-1 and A_4-1 showed over 99% inhibition of H. turcicum spores at 1 mg/ml of 10% ethanol and LD₅₀ of about 600 μg/ml. A₅ showed an LD₅₀ of about 800 μg/ml of 10% ethanol. The ultraviolet, infrared, nuclear magnetic resonance, electron impact mass spectra and field desorption mass spectra showed that these compounds might be related to the previously described phytoalexins A₁ and A₂. They seem to have the following functional groups: aromatic ring, hydroxyl and/or phenolic groups, carbonyl groups, probably a carboxylic acid or ester type and a long aliphatic side chain.     

Effect of cell lipid composition on the formation of nonspecific antibiotic resistance in alkanotrophic rhodococci

The antibiotic resistance and lipid composition of rhodococci grown in rich organic media with gaseous or liquidn-alkanes were studied. Hydrocarbon-grown rhodococci exhibited an increased resistance to a wide range of antibiotics (aminoglycosides, linkosamides, macrolides, β-lactams, and aromatic compounds). The enhanced antibiotic resistance of rhodococci grown onn-alkanes correlated with an increased content of total cell lipids (up to 14–28%) and saturated straight-chain fatty acids (C_16:0, C_18:0, C_21:0) and was accompanied by the appearance of cardiolipin and phosphatidylglycerol in cells. These lipid compounds are supposed to promote the formation of nonspecific antibiotic resistance in rhodococci by decreasing the permeability of their cell envelope to antibiotics.     

Biological activity of organometallic bismuth compounds

Summary The chemical aspects of organometallic bismuth(Ill) compounds are discussed with respect to the stability of the metal-carbon bond, their low dipole moments, and the limited solubility of these complexes in hydrophilic solvents. A new Bi heterocycle, which is of potential interest in terms of stability and solution behaviour, was shown to exist as an intermediate under the conditions in the mass spectrometer.Although generally bismuth organic compounds are extremely toxic, in the 1970s they became important as biocides and this is still being investigated. They have also been discussed as irritation causing chemical warfare agents. While their application in chemotherapy never became very widespread because antibiotics were discovered, in the last few years the antitumor activity of some derivatives has been reported.Abbreviations BE bond energy - IC inhibition concentration - MIC minimal inhibition concentration - electronegativity (Allred and Rochow) - X halogen, pseudohalogen=F, Cl, Br, CN - Me CH₃ - Et C₂H₅ - Bu C₄H₉ - Ph C₆H₅ - Ac CH₃COO - MS mass spectrometry     

Inhibition of the phytopathogenic fungus Fusarium proliferatum by volatile compounds produced by Pseudomonas

The Fusarium head blight of grain cereals is a significant disease worldwide. In Argentina, high levels of contamination with Fusarium proliferatum have been found in crops. Many strains of the Pseudomonas genus antagonize the growth of fungi by different mechanisms, such as the production of antibiotics, siderophores, volatiles, and extracellular enzymes. In this work, we have designed a new system for studying the growth inhibition of F. proliferatum—namely by volatile compounds produced by Pseudomonas fluorescens MGR12. In both rich and minimal media, the bacterium released volatiles that negatively affected the mycelial growth of that phytopathogenic fungus. These bacterial compounds were analyzed by gas chromatography–mass spectrometry, but only a few could be identified by comparing their mass spectra with the libraries of the National Institutes of Standards and Technology MS search.     

Characteristics of mass spectrometric analyses coupled to gas chromatography and liquid chromatography for 22-oxacalcitriol, a vitamin D3 analog, and related compounds

The characteristics of the mass spectra of vitamin D₃ related compounds were investigated by GC–MS and LC–MS using 22-oxacalcitriol (OCT), an analog of 1,25-dihydroxyvitamin D₃, and related compounds. Fragmentation during GC–MS (electron impact ionization) of TMS-derivatives of OCT and the postulated metabolites gave useful structural information concerning the vitamin D₃-skeleton and its side-chain, especially with respect to the oxidation positions of metabolites. In contrast, few fragment ions were observed in LC–MS (atmospheric pressure chemical ionization), showing that LC–MS gave poor structural information, except for molecular mass. However, when comparing the signal-to-noise ratio (S/N) observed during GC–MS and LC–MS analysis for OCT in plasma extracts, the S/N in LC–MS was over ten-times greater than in GC–MS, possibly due to the low recovery on derivatization and thermal-isomerization in GC–MS. Furthermore, both the GC–MS and the LC–MS allowed the analysis of many postulated metabolites in a single injection without any prior isolation of target metabolites from biological fluids by LC. These results suggest that GC–MS and LC–MS analysis for vitamin D₃ related compounds such as OCT each have unique and distinct advantages. Therefore, the complementary use of both techniques enables the rapid and detailed characterization of vitamin D₃ related compounds.     

Identification and Discrimination of Oral Asaccharolytic Eubacterium spp. by Pyrolysis Mass Spectrometry and Artificial Neural Networks

Curie-point pyrolysis mass spectra were obtained from 29 oral asaccharolytic Eubacterium strains and 6 abscess isolates previously identified as Peptostreptococcus heliotrinreducens. Pyrolysis mass spectrometry (PyMS) with cluster analysis was able to clarify the taxonomic position of this group of organisms. Artificial neural networks (ANNs) were then trained by supervised learning (with the back-propagation algorithm) to recognize the strains from their pyrolysis mass spectra; all Eubacterium strains were correctly identified, and the abscess isolates were identified as un-named Eubacterium taxon C₂ and were distinct from the type strain of P. heliotrinreducens. These results demonstrate that the combination of PyMS and ANNs provides a rapid and accurate identification technique.     

Chemical composition of femoral secretions of oviparous and viviparous types of male common lizards Lacerta vivipara

In spite of the importance of chemoreception in intraspecific communication of lizards, only a few studies have examined chemical composition of secretions of lizards. The secretion of the femoral glands of adult male lizards Lacerta vivipara contains a relatively low number (18) of lipophilic compounds in comparison with other related lacertid lizards. These compounds were identified on the basis of mass spectra, obtained by GC-MS. Chemicals included ten steroids (mainly cholesterol) and four carboxylic acids between n-C₁₂ and n-C₁₈, and minor components such as squalene, α-tocopherol, and two waxy esters, which may contribute to avoid oxidation of other lipophilic components in the fairly humid environments occupied by this lizard. Secretions of adult males from oviparous and viviparous populations did not differ in the numbers and quality of chemical compounds, but there were some differences in the relative proportion of some compounds. Males from oviparous populations had lower proportions of hexadecanoic acid and cholestan-3-one, and higher proportions of squalene than viviparous males. These differences might be explained by either small genetic differences between types or due to different microclimatic conditions in the original populations.     

Lithoautotrophic Growth of the Freshwater Colorless Sulfur Bacterium Beggiatoa “leptomitiformis”D-402

The freshwater colorless sulfur bacterium Beggiatoa leptomitiformisD-402 was shown to be capable of lithoautotrophic growth in a batch culture under microoxic conditions at O₂concentrations in the medium of no higher than 0.5 mg/l. The cell yield was maximum at a dissolved oxygen concentration of 0.15 mg/l. A high activity level of key enzymes of the Calvin cycle and of enzymes involved in dissimilatory oxidation of thiosulfate was recorded in the cells. The high rate of CO₂assimilation (112–139 nmol/(min mg protein)) and the cell yield (12 mg dry cells/mmol thiosulfate oxidized), 91–92% of which was accounted for by CO₂carbon, were close to those typical of autotrophic bacteria. Thiosulfate was oxidized almost completely to sulfate, and the fraction of intracellular sulfur in the final products did not exceed 0.2–1.7% of the thiosulfate sulfur. The cell membrane fraction contained cytochromes (b + o) and two cytochromes cwith M _rof 23 and 26 kDa; the soluble fraction contained cytochrome cwith M _rof 12 kDa.     

The 8-isoprostaglandins: Evidence for eight compounds in human semen

Evidence is presented for the existence of a group of 8-iso prostaglandins in human semen, comprising 8-iso PG E₁^*, 8-iso PG E₂, 8-iso PG F_1α, 8-iso PG F_2α and the four corresponding 19-hydroxy prostaglandins. The E and F compounds have been positively identified by comparison of their mass spectra and chromatographic properties with those of authentic standards. Preliminary measurements of levels of these compounds in pooled semen are presented.     

Synthesis,Characterization, and Anti‐Amoebic Activity of N‐(Pyrimidin‐2‐yl)benzenesulfonamide Derivatives

A new series of N‐(pyrimidin‐2‐yl)benzenesulfonamide derivatives, 3a – 3i and 4a – 4i , was synthesized from pyrimidin‐2‐amines, 2a – 2i , with the aim to explore their effects on in vitro growth of Entamoeba histolytica. The chemical structures of the compounds were elucidated by elemental analysis, FT‐IR, ¹H‐ and ¹³C‐NMR, and ESI mass‐spectral data. In vitro anti‐amoebic activity was evaluated against HM1 : IMSS strain of Entamoeba histolytica. The IC₅₀ values were calculated by using the double dilution method. The results were compared with the IC₅₀ value of the standard drug ‘metronidazole’. The selected compounds were tested for their cytotoxic activities by cell‐viability assay using H9C2 cardiac myoblasts cell line, and the results indicated that all the compounds displayed remarkable >80% viabilities to a concentration of 100 μg/ml.     

Some aspects of chemical ionization mass spectroscopy using ammonia as reagent gas: A valuable technique for biomedical and natural products studies

The use of ammonia as reagent gas increases considerably the utility of chemical ionization mass spectroscopic (ci-ms) analysis: compounds of biological interest, such as steroid hormones, bile acids, prostaglandins, phospholipids, alkaloids, antibiotics, etc., display strong pseudomolecular ions (mostly M⁺ + 18). The need for derivatization and/or chromatographic purification of many types of compounds is sharply reduced. Ammonium carbonate or ¹⁵NH₄Cl can be introduced into the direct probe for obtaining satisfactory ci-ms(NH₃) spectra. Bile salts and some bile acid conjugates can be studied without derivatization. Potassium penicillanate gives a strong peak corresponding to the free acid + NH₄⁺. Deproteinized blood samples provide a detailed picture of individual components, such as triglycerides, lysolecithins, cholesterol esters, etc. Frag-mentation patterns for structural information can be generated by adding argon to ammonia. One shortcoming of the ci-ms(NH₃) method is the progressive replacement of halogen with hydrogen.     

Issue information

Benzothiazepine compounds have a wide range of applications such as antibacterial, antidepressants, anticonvulsants, antihypertensives, antibiotics, antifungal, hypnotic, enzyme inhibitors, antitumor, anticancer and anti‐HIV agents. In this study, the synthesis of novel tetralone‐based benzothiazepine derivatives ( 1–16 ) and their in vitro antibacterial activity and human carbonic anhydrase isoenzymes I and II (hCA I and II) inhibitory effects were investigated. Both isoenzymes were purified by sepharose‐4B‐l ‐tyrosine‐sulfanilamide affinity chromatography from fresh human red blood cells. All compounds demonstrated the low nanomolar inhibitory effects on both isoenzymes using esterase activity. Benzothiazepine derivative 2 demonstrated the best hCA I inhibitory effect with K_i value of 18.19 nM. Also, benzothiazepine derivative 7 showed the best hCA II inhibitory effect with K_i value of 11.31 nM. On the other hand, acetazolamide clinically used as CA inhibitor, showed K_i value of 19.92 nM against hCA I and 33.60 nM against hCA II, respectively.     

Oligomycins A and C,major secondary metabolites isolated from the newly isolated strain <Emphasis Type="Italic">Streptomyces diastaticus</Emphasis>

During the screening program for fungicides, one actinomycete strain ECO 00047 was isolated with the potential activity against fungus. According to the morphology and analysis of the nucleotide sequence of the 16S rRNA gene (1500 bp) this isolate was identified as Streptomyces diastaticus. The active compounds were separated by silica gel column chromatography, Sephadex LH-20 gel filtration and then purified by flash chromatography on C₁₈ (20–45 μm). The chemical structure of the bioactive compounds I and II were elucidated, based on the spectroscopic data of MS, IR, UV, ¹H-NMR, ¹³C-NMR and X-ray single crystal diffraction analysis. Compounds I and II were identical with oligomycins A and C, the macrolide antibiotics which have been known to be produced by Streptomyces diastatochromogenes, S. libani and S. avermitilis. The two compounds exhibited a strong activity against Aspergillus niger, Alternaria alternata, Botrytis cinerea and Phytophthora capsici but no activity toward bacteria. Although the two above antibiotics were known, their isolation has so far not been reported from S. diastaticus.     

Five New Oleanane Triterpene Saponins from Camellia petelotii and Their Alpha-glucosidase Inhibitory Activity

Five new triterpenoid glycosides, named campetelosides A–E ( 1–5 ), together with three known compounds, chikusetsusaponin IVa ( 6 ), umbellatoside B ( 7 ), and silvioside E ( 8 ) were isolated from the leaves of Camellia petelotii (Merr.) Sealy. Their chemical structures were determined by interpretations of HR-ESI-MS and NMR spectra. In addition, compounds 1–8 were evaluated for their α-glucosidase inhibitory effects. Compounds 1–3 significantly showed α-glucosidase inhibitory activity with IC₅₀ values of 166.7±6.0, 45.9±2.6, and 395.3±10.5 μM, respectively, compared to that of the positive control, acarbose, with an IC₅₀ value of 200.4±10.5 μM.     

Isolation and partial characterization of antimicrobial compounds from a new strain <Emphasis Type="Italic">Nonomuraea</Emphasis> sp. NM94

An actinomycete strain NM94 was isolated from a Saharan soil sample by a dilution agar plating method using chitin-vitamins B medium supplemented with penicillin. The strain presented the morphological and chemical characteristics of the genus Nonomuraea. On the basis of 16S rDNA analysis and physiological tests, this isolate was found to be quite different from the known species of Nonomuraea and might be new. The strain NM94 secreted several antibiotics on yeast extract malt extract glucose medium that were active against some Gram-positive bacteria, yeast, and fungi. The antibiotics were extracted with dichloromethane and detected by bioautography on silica gel plates using Mucor ramannianus and Bacillus subtilis as the test organisms. Among these antibiotics, a complex called 94A showed interesting antifungal activity. It was selected and purified by reverse-phase HPLC. This complex was composed of five compounds. Spectroscopic studies by infrared, mass, and ¹H NMR of the compounds were carried out. Initial results showed that these molecules differed from the known antibiotics produced by other Nonomuraea species.