Search Results

You are looking at 1 - 10 of 18 items for

  • Author or Editor: Péter Ott x
Clear All Modify Search

The antibacterial effect of the components of clary sage (Salvia sclarea L.) and spearmint (Mentha spicata L. var. crispa (Bentham) Danert) was investigated by means of high-performance thin-layer chromatography-direct bioautography against the Gram-positive soil bacterium Bacillus subtilis (Bs) and Gram-negative bacteria such as a pepper pathogen Xanthomonas euvesicatoria (Xe), a luminescence gene-tagged Arabidopsis pathogen Pseudomonas syringae pv. maculicola (Psm) and a luminescent marine Aliivibrio fischeri (Af). Sclareol, linalool, and linalyl acetate were identified as active components of clary sage and carvone as the antibacterial substance in spearmint. Sclareol inhibited all tested bacteria, linalool and carvone showed antibacterial effect against all Gram-negative strains tested, while linalyl acetate only against Xe and Af. Some minor components of the clary sage essential oil also gave a zone of inhibition when tested on Gram-negative bacterium strains.

Restricted access

Direct bioautography performed with luminescence gene-tagged bacteria enables almost real-time detection of antimicrobial compounds in plant extracts. This method for the detection of chamomile ( Matricaria recutita ) components with antibacterial effect against Bacillus subtilis soil bacteria was more sensitive than commonly used bioautographic visualization by staining with a tetrazolium salt. Some compounds had a strong inhibiting effect only via the bioluminescence measurement. Extraction of antibacterial components of chamomile flowers was most effective with 50% ethanol; slightly lower efficiency was achieved with acetone and methanol, and hexane was least effective. The results were confirmed by using luminescent Pseudomonas syringae pv. maculicola plant pathogen bacteria.

Restricted access

Singlet oxygen ( 1 O 2 )-catalyzed oxidation of water leads to a variety of oxidants (e.g. ozone, O 3 ) in host-parasite relationships as well. It can be detected indirectly in TLC or OPLC zones by use of the simple BioArena system and O 3 -eliminating molecules (e.g. d -limonene and indigo carmine) in the culture medium. It follows from these new findings that not only formaldehyde but also O 3 and related bioreactive compounds may play a crucial role in the mechanism of antibacterial activity of antibiotic-like compounds. The toxic potential of a molecule, however, originates from the ratio of the oxidants produced in the chromatographic spots.

Restricted access

The present and more recent observations suggest that the ozone is an indispensable, endogenous molecule form, and so it can be detected and measured practically in all biological systems. There are already different indirect and direct methods for the detection and measurement of this small molecule. The endogenous formation of ozone in the biological world may open a totally new horizon, e.g., in the topics of disease resistance and cell proliferation. Special efforts and more and more efficient methods are needed for observing the endogenous reactions and functions of this very reactive key molecule.

Restricted access

The accumulation of hydrogen peroxide (H 2 O 2 ) is an early and crucial step in paclitaxel-induced cancer cell death before commitment of the cells to apoptosis. In these intracellular events formaldehyde (HCHO) as endogenous, indispensable component may be present mainly as hydroxymethyl groups and so there is a possibility of its endogenous interaction with H 2 O 2 in which singlet oxygen ( 1 O 2 ) and excited HCHO (H*CHO) can be formed. 1 O 2 can interact with H 2 O molecules and in this interaction dihydrogen trioxide (H 2 O 3 ) is formed. The disproportion of this molecule — among others — results in ozone (O 3 ). It is supposed that this reaction series is also valid for the conditions in layer chromatographic spots after inoculation. Results with paclitaxel support this idea. Using BioArena as a complex bioautographic system the HCHO molecules could be captured with well-known endogenous HCHO capture molecules (l -arginine, glutathione) in the spots of paclitaxel on the TLC/OPLC adsorbent layer after inoculation. Capture of HCHO resulted in a dose-dependent decrease of the antibacterial activity of paclitaxel. The antibacterial activity of paclitaxel in the chromatographic spots can be increased dramatically by using Cu(II) ions as HCHO-mobilizing and carrier ions in the culture medium. The HCHO molecule can N -hydroxymethylate the C3’ amide of paclitaxel. By applying an O 3 scavenger (e.g. indigo carmine) this oxidant, as a key reaction product of HCHO, could be detected indirectly in chromatographic spots of paclitaxel. It seems that these small molecules — from HCHO to endogenous O 3 — may be crucial factors of the mechanism of antiproliferative action of the paclitaxel including killing of bystander cancer cells also. It seems that the basic molecule (paclitaxel) does not have a direct effect on the bacterial cells; its induction of the formation of H 2 O 2 molecules (and indirectly HCHO molecules) may, however, be resulting in this complicated process.

Restricted access

Bioautography can be extended to a complex system called BioArena by linking different steps to it, for example dissolving a variety of compounds in the cell suspension to affect biological activity, measuring putative mediators of antibiosis, for example formaldehyde (HCHO) and hydrogen peroxide (H 2 O 2 ) in the inoculated layer, and performing densitometric and ex and in situ spectroscopic examination to follow the changes in the inhibition zones and active compounds (e.g. antibiotics and toxins). Possibilities of the basic elements of BioArena system are illustrated in this paper by results with aflatoxin B1 (AFB1). Target bacterial cells in the logarithmic growth phase were found to be the most sensitive for direct bioautography. Densitometric signals of bioautograms (negative densitometry) of 0.125–1 μg AFB1 spots showed logarithmic correlation with the amount of AFB1. The HCHO capturer L-arginine decreased whereas the HCHO generator-mobilizer Cu(II) ions increased the antibacterial-toxic effect of AFB1. The latter effect was also confirmed by negative densitometry. Besides higher levels of HCHO, a decrease of H 2 O 2 in the toxin spot was found. HCHO could also originate, among other sources, from demethylation of AFB1, which is apparent from the Fourier transform Raman spectra obtained in situ from the AFB1-containing spots. These results support the suggested role of HCHO and its reaction products with H 2 O 2 (e.g. singlet oxygen ( 1 O 2 ), ozone (O 3 )) in the antibacterial-toxic effect of AFB1.

Restricted access

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.

Restricted access

The greater celandine ( Chelidonium majus L.), a well-known source of isoquinoline alkaloids, has a long history of use as a medicinal plant. Although the antimicrobial activity of Chelidonium alkaloids against pathogenic bacteria has been reported, the mechanism of this action is almost unknown. The BioArena system, which integrates the modern method and biological results of bioautography with TLC and/or OPLC, is especially suitable for investigating biochemical interactions in the adsorbent layer after chromatographic separation. The antimicrobial effect of alkaloids obtained from Chelidonium root has been demonstrated by use of this system. It was assumed that the antibiotic activity of chelidonium alkaloids was a result of formation of formaldehyde. It was also assumed that addition of endogenous HCHO-capture molecules, for example l -arginine and glutathione, to the culture medium reduces the antibacterial activity of Chelidonium alkaloids whereas Cu(II) ions enhance the effect. The results obtained support these assumptions and our earlier observations that HCHO and its reaction products are very important in the antibiotic action of these compounds. These small molecules (l -arginine and glutathione) can capture HCHO molecules mobilized by alkaloids and possibly by pathogen cells, and may be responsible for reduced antibacterial effect. The HCHO-mobilizing power of Cu(II) ions dramatically enhanced the antibiotic effect. The BioArena system is highly suitable for studying special interactions in the adsorbent layer.

Restricted access
JPC - Journal of Planar Chromatography - Modern TLC
Authors: Ágnes Móricz, Györgyi Horváth, Péter Molnár, Béla Kocsis, Andrea Böszörményi, Éva Lemberkovics and Péter Ott

The composition of the essential oil of Thymus vulgaris L. has been determined by GC-FID and GC-MS. Because separation of thymol, carvacrol, and linalool, components of the essential oil, was more efficient by overpressured layer chromatography (OPLC) than by conventional thin-layer chromatography (TLC), the forced flow technique was used before biological detection. All three test compounds had antibacterial effect against the phytopathogenic bacterium Pseudomonas syringae pv. maculicola, in bioautography, although in essential oil thymol was present in sufficient quantity to produce an inhibiting zone in the adsorbent layer. In BioArena investigations, when reduced glutathione as a formaldehyde (HCHO) capturer was dissolved in the cell suspension before bioautographic exposure to the essential oil, the characteristic inhibiting activity of thymol and carvacrol against Bacillus subtilis soil bacteria was reduced, whereas the presence of the HCHO precursors NGmonomethyl-l-arginine or N ɛ-monomethyl-l-lysine enhanced their antibacterial effect. These results suggest that HCHO and its reaction products may be involved in the antibacterial activity of thymol and carvacrol.

Restricted access

Overpressured layer chromatography (OPLC), ensuring pumpforced constant mobile phase flow and the possibility of overrun, offers the expanded exploitation of fine-particle adsorbent layers for a longer development distance. Using an infusion—transfusion OPLC method with a 26-cm long development, the separation of clove, rosemary, eucalyptus, tea tree, spearmint, thyme, and cinnamon bark essential oil components was achieved with good resolutions. In the combination of OPLC and Aliivibrio fischeri assay, the main essential oil components eugenol, borneol, (−)-R-carvone, thymol, and trans-cinnamaldehyde exhibited antibacterial effect. The OPLC—2,2-diphenyl-1-picrylhydrazyl (DPPH*) test showed two antioxidant components: eugenol and thymol.

Restricted access