Purification and biological activity of acidic polysaccharide from leaves of Thymus vulgaris L.
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Polysaccharides are involved in biological responses and can activate complement system, which plays an important role in primary host defense mechanisms. We investigated anticomplementary activities from spice plants and selected thyme (Thymus vulgaris L.) as a potent complementary activator. Acidic polysaccharide (TV-3-IIIA-IIa) purified from the hot-water extract of thyme leaves by DEAE-Toyopearl 650C, Butyl-Toyopearl 650M and Sepharose CL-6B column chromatography and preparative HPLC. The purified polysaccharide, TV-3-IIIA-IIa showed potent anticomplementary activity via classical and alternative pathway with the increase proportional to dosage. TV-3-IIIA-IIa seemed to be a homogenous polymer from the results of HPLC and its molecular mass was estimated as 180 kDa. TV-3-IIIA-IIa mainly consisted of galacturonic acid (44.8 mol%), glucuronic acid (16.7 mol%), arabinose (11.1 mol%), rhamnose (9.2 mol%), galactose (8.9 mol%) and small amounts of glucose, xylose, mannose and fucose. By methylation analysis and reactivity to beta-glucosyl Yariv reagent, TV-3-IIIA-IIa was assumed to contain small amounts of type II arabinogalactan and large amounts of pectin-like polysaccharides in the structure. Based upon these results, TV-3-IIIA-IIa was suggested to be a complement activator. (+info)
Inhibition of listeriolysin O and phosphatidylcholine-specific production in Listeria monocytogenes by subinhibitory concentrations of plant essential oils.
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Successful infection by Listeria monocytogenes is dependent upon a range of bacterial extracellular proteins including a cytolysin termed listeriolysin O and phosphatidylcholine-specific phospholipase C. Five plant essential oils--bay, clove, cinnamon, nutmeg and thyme--significantly reduced the production of listeriolysin O by L. monocytogenes. The greatest change was observed after culture with oil of thyme, which reduced haemolysis to 52.1 haemolytic units (HU)/ml compared with 99.8 HU/ml observed with the control. Oil of clove was the only oil that also significantly reduced phosphatidylcholine-specific phospholipase C activity. These changes were observed despite the oils causing no change to the final bacterial concentration or total extracellular protein concentration. (+info)
Thymol, a constituent of thyme essential oil, is a positive allosteric modulator of human GABA(A) receptors and a homo-oligomeric GABA receptor from Drosophila melanogaster.
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The GABA-modulating and GABA-mimetic activities of the monoterpenoid thymol were explored on human GABAA and Drosophila melanogaster homomeric RDLac GABA receptors expressed in Xenopus laevis oocytes, voltage-clamped at -60 mV. The site of action of thymol was also investigated. Thymol, 1-100 microm, resulted in a dose-dependent potentiation of the EC20 GABA response in oocytes injected with either alpha1beta3gamma2s GABAA subunit cDNAs or the RDLac subunit RNA. At 100 microm thymol, current amplitudes in response to GABA were 416+/-72 and 715+/-85% of controls, respectively. On both receptors, thymol, 100 microm, elicited small currents in the absence of GABA. The EC50 for GABA at alpha1beta3gamma2s GABAA receptors was reduced by 50 microm thymol from 15+/-3 to 4+/-1 microm, and the Hill slope changed from 1.35+/-0.14 to 1.04+/-0.16; there was little effect on the maximum GABA response. Thymol (1-100 microm) potentiation of responses to EC20 GABA for alpha1beta1gamma2s, alpha6beta3gamma2s and alpha1beta3gamma2s human GABAA receptors was almost identical, arguing against actions at benzodiazepine or loreclezole sites. Neither flumazenil, 3-hydroxymethyl-beta-carboline (3-HMC), nor 5alpha-pregnane-3alpha, 20alpha-diol (5alpha-pregnanediol) affected thymol potentiation of the GABA response at alpha1beta3gamma2s receptors, providing evidence against actions at the benzodiazepine/beta-carboline or steroid sites. Thymol stimulated the agonist actions of pentobarbital and propofol on alpha1beta3gamma2s receptors, consistent with a mode of action distinct from that of either compound. These data suggest that thymol potentiates GABAA receptors through a previously unidentified binding site. (+info)
New monoterpene glucoside from the aerial parts of thyme (Thymus vulgaris L.).
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A new monoterpene glucoside (1) was isolated from a methanol extract of the dried aerial parts of thyme (Thymus vulgaris L.), together with known 2- and 5-beta-D-glucopyranosylthymoquinols (2 and 3, respectively), and (-)-angelicoidenol-beta-D-glucopyranoside (4). The structure of 1 was elucidated to be (R)-p-cymen-9-yl beta-D-glucopyranoside by spectral evidence and enantioselective synthesis from (R)- and (S)-p-cymen-9-ol derived from p-cymen-8-ol. (+info)
Content and composition of the essential oil of Thymus serpyllum L. growing wild in Estonia.
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OBJECTIVE: The aim of this work was to analyze the essential oil content and its composition in the drug (Serpylli herba) of wild thyme (Thymus serpyllum L.) originating from 20 different natural places of growth in Estonia. MATERIAL AND METHODS: The quantitative content of essential oil was determined according to the method of European Pharmacopoeia. Gas chromatographic analysis of essential oils was carried out using a gas chromatography with flame ionization detector on two fused silica capillary columns with bonded stationary phases NB-30 and SW-10. The identification of the oil components was accomplished by comparing their retention indices on two columns with the retention indices values of standard compounds, with our retention indices data bank and with literature data. The results obtained were confirmed by gas chromatography / mass spectrometry. RESULTS: The content of essential oil is between 0.6 and 4 ml/kg and usually is not in conformity with European Pharmacopoeia standard (3 ml/kg). There were 55 components identified in the essential oil of wild thyme of Estonian origin. Differently from the data in the literature of foreign countries, thymol and carvacrol are not the main components of the essential oil of wild thyme growing in Estonia. The main components here are (E)-nerolidol, caryophyllene oxide, myrcene, (E)-beta-caryophyllene and germacrene D. CONCLUSION: In Estonia, the (E)-nerolidol-caryophyllene oxide, (E)-nerolidol-myrcene and myrcene chemotypes of wild thyme drug are distinguishable. (+info)
A new hydroxyjasmone glucoside and its related compounds from the leaf of thyme.
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From the polar portion of the methanol extract of thyme (leaf of Thymus vulgaris; Labiatae), which has been used as a stomachic, carminative, a component of prepared cough tea, and as a spice, a new hydroxyjasmone glucoside, (Z)-5'-hydroxyjasmone 5'-O-beta-D-glucopyranoside was isolated together with five related compounds and four aromatic compounds. The structures of the new compound was clarified by spectral investigation. (+info)
Coumarin and flavone derivatives from estragon and thyme as inhibitors of chemical mediator release from RBL-2H3 Cells.
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Estragon and thyme extracts showed potent inhibitory activities against chemical mediator release from rat basophilic leukemia RBL-2H3 cells. 7-Methoxycoumarin was isolated from estragon, and 5,4'-dihydroxy-6,7,3'-trimethoxyflavone, 5,4'-dihydroxy-6,7,8,3'-tetramethoxyflavone, 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone and luteolin were isolated from thyme as active components. Structure-activity relationship studies among the active isolates and their related compounds indicated that the oxygen-containing functional group at the 7-position of the coumarin structure was advantageous for the inhibitory activity and that methylation of the hydroxyl group at the 4'-position of the flavone structure was disadvantageous. It was also found that coumarin derivatives inhibited an earlier step than intracellular calcium release and proteinkinase C activation, while flavones inhibited a later step or both earlier and later steps. (+info)
Effects of plant extracts on angiogenic activities of endothelial cells and keratinocytes.
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Numerous bioactive chemical compounds of plant origin may influence the angiogenic activity of various cell types and may thus affect the formation of blood vessels. Here we present the angiogenic effects of extracts of edible plants collected in Crete, Southern Italy and Southern Spain. Extracts have been applied to cultured human microvascular endothelial cells (HMEC-1), human umbilical vein endothelial cells (HUVEC) and human keratinocytes (HaCaT). About half out of 96 extracts exerted an inhibitory effect on HMEC-1 proliferation. Additionally, we have noted the inhibitory effects of extracts on HUVEC differentiation on a Matrigel layer. None of the extracts showed a stimulatory activity. The extract of Thymus piperella exerted moderate inhibitory effect on cobalt-chloride induced VEGF synthesis, however, CoCl(2)-induced activation of hypoxia responsive element of VEGF promoter was significantly attenuated only by extract of Origanum heracleoticum. Our study indicates that extracts of local food plants, of potential value as nutraceuticals, contain chemical compounds which may inhibit angiogenesis. Demonstration of their real influence on human health requires, however, extensive animal studies and controlled clinical investigations. (+info)