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

Application of direct bioautography and SPME-GC-MS for the study of antibacterial chamomile ingredients

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

Evaluation of Hungarian Wines for Resveratrol by Overpressured Layer Chromatography

A method, including solid phase extraction sample preparation, overpressured layer chromatographic separation and subsequent densitometric evaluation, was developed for measurement of total resveratrol (cis- and trans-isomers) content of wine. The amount of resveratrol was determined in wine samples from different winemaking regions of Hungary. The total resveratrol was high in Hungarian red wines (3.6–11 mg/L), and much lower in white ones (0.04–1.5 mg/L)

Study of trace elements in BioArena system and in in vivo conditions

The adsorbent layer system is especially suitable for the biological evaluation of different compounds and trace elements as well. Present experiments showed that formaldehyde (HCHO) molecules participate in the antibiotic activity of Cu (II) ion, an „old antibiotic”. The elimination of HCHO from the chromatographic spots (e.g. by reduction or capturing) resulted in a characteristic decrease of the antibiotic effect of trace elements. The trace elements are HCHO carriers and generate a double effect (first step: deprivation of HCHO as also biological effect; second step: release of HCHO with big killing activity). These features offer good opportunities for influencing fundamental biochemical pathways. It has been established that the trace elements (mainly transition metal ions as e.g. Ni(II) ion) always generate quadruple, bioequivalent, specific immune-stimulating activity in plants with a non-linear dose-response. HCHO and its reaction products (mainly O3) are responsible also for this latter activity

Application of overpressured layer chromatography combined with digital autoradiography and mass spectrometry in the study of deramciclane metabolism

Overpressured layer chromatography was combined with the highly sensitive and rapid digital autoradiography (DAR) and mass spectrometry to separate, detect, and identify H-3- and C-14-labeled deramciclane metabolites in different biological matrixes. Several minor and major metabolites were separated from plasma and urine samples. The radioactive metabolites localized by DAR were scraped from the thin-layer chromatographic plate and transferred to a mass spectrometer for structure identification. Several metabolites were isolated and characterized, including hydroxy-N-desmethyl deramciclane, which is described in detail. The combination of techniques is efficient and has good sensitivity: about 2 mu g metabolite from a biological matrix was isolated and identified this way

Epoxy modified silicas for HPLC studied by

Epoxy monomer and polymer chains have been prepared on a silica substrate. In all cases in addition to the awaited reaction a zip-polymerisation of the grafts along the silica surface occurs. In the monomer sample there exist some simple grafts without lateral chemical reactions but they are neither the only ones neither the most abundant