Overpressured layer chromatography: from the pressurized ultramicro chamber to BioArena system

The pressurized ultramicro (UM) chamber as a closed adsorbent layer chamber enables the use of a special chromatoplate and a pump to increase and optimize the mobile phase flow velocity through an optional development distance in an adsorbent layer. This chamber is the basic instrument of overpressured-layer chromatography (OPLC), which is a separation technique that combines the advantages of conventional TLC/HPTLC with those of HPLC. The versions of OPLC instrument, the character and achievement of off-line and on-line OPLC systems in analytical and preparative use are described. The development of BioArena as a complex bioautographic system means an exploitation of the unique advantages of planar-layer system for detection, isolation and identification of new antimicrobials, antineoplastics, biopesticides and other biologically active substances as well as for studying fundamental biochemical reactions and mechanisms

Stability of one-step and linear multistep methods - a matrix technique approach

We investigate the stability of one-step and linear multistep methods from a new direction. Our aim is to modify the long and technical proof which is consequently omitted in almost every textbook and make it user-friendly. In the literature the techniques of numerical solution of initial value problems and boundary value problems seem to have almost nothing in common which is quite surprising. Our new approach uses matrix techniques opposed to the usual recursion approach, thus applying the techniques of boundary value problems to initial value problems. Even though the proof remains long, it is easier to follow and connects two seemingly separated areas, consequently this approach might have educational profit

Bioassay-guided isolation and identification of antimicrobial compounds from thyme essential oil by means of overpressured layer chromatography, bioautography and GC-MS

A simple method is described for efficient isolation of compounds having an antibacterial effect. Two thyme (Thymus vulgaris) essential oils, obtained from the market, were chosen as prospective materials likely to feature several bioactive components when examined by thin layer chromatography coupled with direct bioautography as a screening method. The newly developed infusion overpressured layer chromatographic separation method coupled with direct bioautography assured that only the active components were isolated by means of overrun overpressured layer chromatography with online detection and fractionation. Each of the 5 collected fractions represented one of the five antimicrobial essential oil components designated at the screening. The purity and the activity of the fractions were confirmed with chromatography coupled various detection methods (UV, vanillin-sulphuric acid reagent, direct bioautography). The antibacterial components were identified with GC-MS as thymol, carvacrol, linalool, diethylphthalate, and alpha-terpineol. The oil component diethyl-phthalate is an artificial compound, used as plasticizer or detergent bases in the industry. Our results support that exploiting its flexibility and the possible hyphenations, overpressured layer chromatography is especially attractive for isolation of antimicrobial components from various matrixes

Biogén aminok meghatározása túlnyomásos rétegkromatográfiás módszerrel

Élelmiszerekben elõforduló biogén aminok meghatározására túlnyomásos rétegkromatográfiás módszert dolgoztak ki. A Personal OPLC-re kidolgozott módszert trappista sajtban és karfiolban elõforduló biogén aminok gyors és hatékony kimutatására és mennyiségi meghatározására alkalmazták. Overpressured Layer Chromatographic Method was developed for determination of biogenic amines in foods. The method developed for the Personal OPLC equipment could be used for rapid and efficient qualitativ and quantitativ determination of biogenie amines in cheese of type Trappista and in couliflower. Eine dünschichtchromatographische Methode mit Überdruck wurde für die Bestimmung der in Lebensmitteln vorkommenden biogenen Amine erarbeitet. Die für Personal OPLC erarbeitete Methode wurde für den schnellen und effektiven Nachweis sowie für die quantitative Bestimmung von biogenen Aminen in Trappista Käse und Blumenkohl angewandt

A transz-rezveratrol és rokonvegyületek vizsgálata BioAréna-rendszerben

A vörös bor kedvező biológiai hatásaiért elsősorban a kékszőlő termés héjából a vörösborba kerülő sztilbénvázas transz-rezverátrol (TR) a felelős. A TR sokrétű hatásának értelmezése a hatás mechanizmus teljesen uj megközelítését igényelte. Feltételeztük korábban, majd bizonyítottuk , hogy egyrészt az antibiotikus hatású TR-rel együtt a szőlőnövényben a formaldehid (HCHO)kötött formában együttesen fordul elő, másrészt kémiai reakciókban pedig bizonyitottuk hogy a TR reakcióba lép a HCHO-val, amikor nagyon reaktiv hidroximetil-származékok képződnek.Az elmult időszakban a TR és a HCHO közötti reakciókat mikrokémiai szinten tanulmányoztuk. Az un BioAréna rendszer (a direkt bioautográfia továbbfejlesztett változata és a müveleti lépések koordinálása) lehetővé tette a TR és a HCHO közötti reakciók szisztematikus tanulmányozását. Megállapítottuk, hogy a TR kettős hatást ad, melynek első lépése a HCHO molekulák felvétele az adott rendszerből, s ez önmagában biológiai (védő) hatást jelent. Az igy keletkezett uj hidroximetil TR származékok antiproliferativ hatást mutatnak (pl. mikrobák és tumor sejtek ellen).Ozon-befogó molekulák adásával nem tudtuk a TR antibakteriális hatását csökkenteni. A BioAréna-rendszerben különböző hazai és külföldi fehér és vörös borfajták antibakteriális spektrumát is összehasonlitottuk: a fehér borfajták általában mérsékelt antibiotikus hatásukkal tüntek ki minőségi és mennyiségi szinten egyaránt.. | For the beneficial activities of red wine mainly a stilbene derivative, trans-resveratrol (TR) which is originating from the skin of red grapes into the red wine, is responsible. The explanation of the multiple biological activity of TR required a totally new approach to the mechanism of action. We supposed earlier and then proved that the TR in the grape plant occurs together with bound formaldehyde (HCHO) and we proved in chemical reactions that TR can react with HCHO forming very reactive hydroxymethyl derivatives. More recently the interaction between TR and HCHO can be studied in microchemical level: the BioArena system (the developed version of direct bioautography and the coordination of operating steps) gave a possibility for the systematic study of the interactions between TR and HCHO . It has been established that TR generates a double effect. The mobilisation of HCHO from a given biological unit (e.g. tissue) with TR (first step) may cause a chemopreventive /biological effect and the reaction products (hydroxymethyl derivatives) between TR and HCHO (second step) may exert a killing/inhibiting effects on pathogens and/or cancer cells (double effect). Using ozone (O3) capture molecules (e.g. limonene) in the chromatographic spots the antibacterial activity of TR didn't decrease. Comparison of antibacterial activity of white and red wines showed the moderate antibacterial activity of white wines quantitatively and qualitatively, alike.

Reliable Numerical Modelling of Malaria Propagation

summary:We investigate biological processes, particularly the propagation of malaria. Both the continuous and the numerical models on some fixed mesh should preserve the basic qualitative properties of the original phenomenon. Our main goal is to give the conditions for the discrete (numerical) models of the malaria phenomena under which they possess some given qualitative property, namely, to be between zero and one. The conditions which guarantee this requirement are related to the time-discretization step-size. We give a sufficient condition for some explicit methods. For implicit methods we prove that the above property holds unconditionally

Notes on the basic notions in nonlinear numerical analysis

In this paper we investigate the numerical solution of non-linear equations in an abstract (Banach space) setting. The main result is that the convergence can be guaranteed by two, directly checkable conditions (namely, by the consistency and the stability). We show that these conditions together are a sufficient, but not necessary condition for the convergence. Our theoretical results are demonstrated on the numerical solution of a Cauchy problem for ordinary differential equations by means of the explicit Euler method

In-situ Clean-up and OPLC Fractionation of Chamomile Flower Extract Searching Active Components by Bioautography

Bioassay-guided isolation of antibacterial components of chamomile flower methanol extract was performed by OPLC with on-line detection, fractionation combined with sample clean-up in-situ in the adsorbent bed after sample application. The antibacterial effect of the fractions and the separated compounds remained on the adsorbent layer (do not overrun during OPLC separation) was tested with direct bioautography (DB) against the bioluminescent Pseudomonas savastanoi pv. maculicola and Vibrio fischeri. The fractions with great biologically activity were analysed by SPME-GC-MS and LC-MS/MS and the two active uneluted compounds were characterized by OPLC-MS using interface. Mainly essential oil components, coumarins, flavonoids, phenolic acids and fatty acids were identified in the fractions