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Summary

A thin-layer chromatography (TLC)–bioautography–mass spectrometry (MS) method coupled with a liquid chromatography–MS-controlled autopurification system was developed and applied for screening and isolating natural dipeptidyl peptidase IV (DPP IV) inhibitor from plant extracts. An unknown constituent with potential DPP IV inhibitory activity from bulbs of Fritillaria cirrhosa was discovered using TLC–bioautography, followed by using a TLC interface with mass spectrometry to obtain m/z of the target compound, and the purification of the compound was directly achieved with a mass-directed autopurification system for 40 runs of injection. Finally, 2.1 mg of the compound was obtained and identified as peimisine by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The half maximal inhibitory concentration (IC50) of DPP IV inhibitory activity was determined at 80.5 µm comparing to 58.0 µm of the standard DPP IV inhibitor diprotin A by a spectrophotometric method.

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It has been established, by use of bioautographic detection with the phytopathogenic bacteria Pseudomonas savastanoi pv. phaseolicola , that the common aflatoxins have antimicrobial activity after OPLC separation. Our preliminary results suggest this antimicrobial activity originates from the activity of formaldehyde formed by the bacterial cells and/or from the methoxy groups of aflatoxin molecules.

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L. Botz, S. Nagy, B. Kocsis , and Gy. Horváth , Planar Chromatographic Aspects of Direct Bioautography, in Sz. Nyiredy (Ed.) Proc. Int. Symp. Planar Separations — Planar Chromatography 2000, Hungary, June 2000, pp. 77

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Commercially available hop pellets of different origins were extracted by use of ethanol and water, chromatographed on silica layers by use of nonaqueous eluents, chemically derivatized and observed in ultraviolet (UV) light for the localization of component bands. The plates were developed in optimized systems, and direct bioautographic method by use of Bacillus subtilis and Escherichia coli strains was applied for the examination of the antimicrobial activities of hop components. The method enables for the identification of bactericidal/bacteriostatic components in the extracts of different polarities and shows differences in the composition of extracts from various varieties from an antimicrobial point of view.

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Third Millennium 2001 L. Botz, B. Kocsis , and S. Nagy , Bioassays: Microbial tests. Bioautography. In: P

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. M. Choma , W. Jesionek , Instrumental Thin-Layer Chromatography: Effects-Directed Biological Detection: Bioautography , Elsevier , Amsterdam , 2014 . [4

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The shiitake mushroom is well known for its health-beneficial effects. In this study we examined its antimicrobial activity by use of bioautography. After bioactivity detection we identified one major antimicrobial compound by use of infrared spectroscopy and gas chromatography. It shares similarity with well-known fatty acids.

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The isolation and characterization of antibacterial chamomile components were performed by the use of direct bioautography and solid phase microextraction (SPME)-gas chromatography (GC)-mass spectrometry (MS). Four ingredients, active against Vibrio fischeri, were identified as the polyacetylene geometric isomers cisand trans-spiroethers, the coumarin related herniarin, and the sesquiterpene alcohol (−)-alpha-bisabolol.

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Rapid identification of known compounds, i.e., dereplication, has become a strategically important area for the natural-product chemists involved in bioprospecting of microbes for novel bioactive metabolites. Among microbial biodiversity, endophytic fungi represent an abundant and dependable source of structurally diverse bioactive metabolites. During the course of screening for antimicrobial secondary metabolites from endophytic fungi, an antimicrobial metabolite was identified from the ethyl acetate extract obtained from the culture broth of Xylaria sp., an endophytic fungus from Ficus pumila Linn. (Moraceae) that exhibited a broad spectrum of antimicrobial activity against human and phytopathogenic bacteria and fungi. Chemical investigation of the ethyl acetate fraction using thin-layer chromatography (TLC) bioautography and LC-hyphenated techniques led to the identification of a known benzoic acid derivative. Here, we describe the application of analytical strategies (TLC-bioautography) and hyphenated spectroscopic techniques (liquid chromatography-photodiode array detector-mass spectrometry [LC-PDA-MS]) for the dereplication of antimicrobial metabolites.

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Fluoroquinolones are a relatively new group of synthetic antibiotics (chemotherapeutics) widely used both in human and animal treatment. Because veterinary enrofloxacin and its main metabolite ciprofloxacin, a widely used human antibiotic, can be present as residues in milk, there is a need for methods for their separation and determination. Matrix solid-phase dispersion (MSPD) on a siliceous sorbent was used for isolation and concentration of enrofloxacin and ciprofloxacin residues from cows’ milk. This preseparation method was combined with high-performance liquid chromatography and with thin-layer chromatography-direct bioautography. Mean recoveries were calculated for different levels of the antibiotics in milk. The results revealed that thin-layer chromatography-direct bioautography can be used for the screening of enrofloxacin and ciprofloxacin at the maximum residue level stipulated for milk by the European Union.

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