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PubMed1993

Genotoxicity of nitrosated red wine and of the nitrosatable phenolic compounds present in wine: tyramine, quercetin and malvidine-3-glucoside.

Phenolic compounds and biogenic amines are known to be present in some foodstuffs which become directly genotoxic after nitrosation in vitro. Red wine has previously been shown to be genotoxic and this activity has been attributed mainly to flavonoids. Besides flavonoids, red wine contains a multiplicity of compounds, including biogenic amines. Using the Ames assay and the SOS chromotest, this study has shown that red wine and some of the nitrosatable molecules present in wine become directly genotoxic on nitrosation in vitro: these include the phenolic molecules tyramine, quercetin and malvidine-3-glucoside, whereas phenylethylamine and histamine were negative on nitrosation. Interestingly, quercetin had been predicted to be negative after nitrosation, using the CASE methodology. The concentrations of these three positive nitrosatable compounds in wine were determined by HPLC. Comparison of these concentrations and their respective levels of genotoxicity suggests that the genotoxicity after nitrosation is probably attributable to other molecules. It is also possible that synergistic effects may occur between various nitrosatable compounds in wine.

Anthocyanins↗
PubMed2004

Bi-enzyme sensor based on thick-film carbon electrode modified with electropolymerized tyramine.

Bi-enzyme sensor based on thick-film epoxy-carbon electrode modified with polytyramine has been developed and examined for the determination of peroxidase substrates and cholinesterase inhibitors. Polytyramine was obtained on the electrode surface by repeated scanning of the potential from +600 to +1800 mV vs. Ag/AgCl in tyramine solution. The enzymes were immobilized in the polytyramine matrix by cross-linking with glutaraldehyde. The biosensor developed provides a reliable and inexpensive way for preliminary testing of common environmental pollutants with a single sensor in accordance with assumed toxic effect by the choice of appropriate substrate and measurement conditions. The bi-enzyme sensor makes it possible to determine substituted phenols and aromatic amines in the micromolar range of their concentrations and anticholinesterase pesticides with detection limits of 0.1 (Coumaphos) and 0.03 micromol l(-1) (Chloropyrifos-methyl).

Biosensing Techniques↗
PubMed2006

Determination of octopamine, synephrine and tyramine in Citrus herbs by ionic liquid improved 'green' chromatography.

Without adding any volatile organic solvents, aqueous solutions of room temperature ionic liquids (RTILs) were used as 'green' mobile phases to determine octopamine, synephrine and tyramine by liquid chromatography. The problems of the adrenergic amines separation, such as band tailing, low retention and low resolution were solved successfully by using RTIL. The effect of 1-ethyl-3-methylimidazolium tertafluoroborate ([EMIM][BF4]) was the best in the six investigated RTILs. The concentration of [EMIM][BF4], mobile phase pH and column temperature, which influenced the chromatographic behaviors of the analytes, were investigated in detail. The change of retention factors caused by pH shift was obviously suppressed by [EMIM][BF4]. The sensitivity, accuracy and repeatability of this method were found to be satisfactory. The contents of adrenergic amines in several Citrus herbs and extracts, such as Fructus aurantii immaturus, were simultaneously determined by this 'green' chromatographic method.

Adrenergic alpha-Agonists↗
PubMed2005

Molecular response of Drosophila melanogaster tyramine receptor cascade to plant essential oils.

This paper reports the role of the tyramine (TA) receptor cascade in the insecticidal activity of plant essential oils. A TA receptor cDNA encoding a putative seven transmembrane domain G-protein coupled receptor was amplified from Drosophila melanogaster head cDNA phage library. The encoded protein contains 601 amino acids and has a sequence similar to other biogenic amine receptors. This protein was expressed in Drosophila S2 cells for radioligand binding studies with the ligand 3H-TA. Competitive binding studies comparing biogenic amines that could potentially function as endogenous ligands have demonstrated that this receptor had the highest affinity for TA (Ki=1.27 microM) followed by DL-octopamine, dopamine, serotonin and histamine. TA decreased the forskolin-increased cAMP levels (IC50=5.802 microM) and increased [Ca2+]i through the receptor expressed in S2 cells. The toxicity rank order of the tested plant essential oils against wild type D. melanogaster fly demonstrated a pattern similar to their effect on receptor binding activity and changes in cAMP level and [Ca2+]i. The toxicity of two of these chemicals was eliminated when tested against the TA receptor mutant (TyrRneo30) Drosophila strain. Therefore, the data indicates a correlation between cellular changes and insecticidal activity of tested plant essential oils, and suggests that the toxicity of at least two of these chemicals is mediated through the TA receptor.

Animals↗
PubMed2005

Multiplex PCR for colony direct detection of Gram-positive histamine- and tyramine-producing bacteria.

Formation of biogenic amines (BA) may occur in fermented foods and beverages due to the amino acid decarboxylase activities of Gram-positive bacteria. These compounds may cause food poisoning and therefore could imply food exportation problems. A set of consensual primers based on histidine decarboxylase gene (hdc) sequences of different bacteria was designed for the detection of histamine-producing Gram-positive bacteria. A multiplex PCR based on these hdc primers and recently designed primers targeting the tyrosine decarboxylase (tyrdc) gene was created. A third set of primers targeting the 16S rRNA gene of eubacteria was also used as an internal control. This multiplex PCR was performed on extracted DNA as well as directly on cell colonies. The results obtained show that this new molecular tool allowed for the detection of Gram-positive histamine- and/or tyramine-producing bacteria. The use of this molecular tool for early and rapid detection of Gram-positive BA-producing bacteria is of interest in evaluating the potential of cultured indigenous strains to produce biogenic amines in a fermented food product as well as to validate the innocuity of potential starter strains in the food industry.

Animals↗
PubMed1997

Memory enhancement mediated by the steroid sulfatase inhibitor (p-O-sulfamoyl)-N-tetradecanoyl tyramine.

The intent of this study was to determine whether altering the metabolism of neurosteroids via blockade of the enzyme, steroid sulfatase, could enhance memory retention in rats. The steroid sulfatase inhibitor p-O-(sulfamoyl)-N-tetradecanoyl tyramine (DU-14) was administered alone and in combination with the neurosteroid dehydroepiandrosterone sulfate (DHEAS) to rats which were then tested for the reversal of scopolamine-induced amnesia. A single 30 mg/kg IP dose of DU-14 produced a significant inhibition of steroid sulfatase activity in both brain (14.8%), and liver (85.2%) tissues, 24 hours following administration. In a passive avoidance test, DU-14 enhanced the reversal of amnesia by DHEAS. These results suggest that steroid sulfatase inhibition can potentiate the memory enhancing properties of DHEAS.

Adjuvants, Anesthesia↗
PubMed1997

Chronic steroid sulfatase inhibition by (p-O-sulfamoyl)-N-tetradecanoyl tyramine increases dehydroepiandrosterone sulfate in whole brain.

Dehydroepiandrosterone sulfate (DHEAS) is a neurosteroid which functions as a negative allosteric modulator of the GABA(A) receptor-gated chloride channel. Steroid sulfatase inhibitors including (p-O-sulfamoyl)-N-tetradecanoyl tyramine (DU-14), can potentiate the blockade of the amnestic effects of scopolamine by exogenously administered DHEAS. Moreover, when administered over a 15 day period, DU-14 can block scopolamine amnesia without the concurrent administration of DHEAS. Since the enzyme, steroid sulfatase, facilitates the hydrolysis of the sulfate moiety from DHEAS, the intent of this study was to determine whether chronic administration of DU-14 could increase whole brain concentrations of endogenous DHEAS. Rats were administered DU-14 or corn oil vehicle for 15 days. Following the last day the animals were sacrificed and the brains were removed and analyzed for DHEAS content. DU-14 increased the whole brain concentration of DHEAS 77.6%, from 0.65 +/- 0.06 to 1.15 +/- 0.12 microg/g (mean +/- SEM). This result suggests that steroid sulfatase inhibitors may enhance cognitive function following chronic treatment by increasing the concentration of excitatory neurosteroids such as DHEAS in the brain. Steroid sulfatase inhibitors, therefore, may provide a novel mechanism for facilitating central nervous system function.

Animals↗
PubMed1999

Lanthanides stimulate [3H]tyramine binding in the rat striatum.

Low (up to 100 nM) and high (approximately 100 microM) concentrations of lanthanides and Ca2+-ions, respectively, stimulated [3H]tyramine binding ([3H]TY) to rat striatal membranes, a putative marker for the vesicular transporter of dopamine. On the other hand, lanthanides (approximately 100 microM) inhibited or stimulated TY binding in striatal and extrastriatal (cortex, cerebellum) tissues, respectively. The binding increases by lanthanum (La3+) appeared to depend on endogenous Ca2+, whereas, those induced in EDTA-pretreated membranes were Ca2+-independent. The La3+-induced, apparent increase in the Bmax for [3H]TY binding seemed to reflect a retarded rate of dissociation of the ligand from its targets, rather than a larger availability of functionally-relevant, vesicular transport-related TY sites. This indicates uncertain mechanisms of present La3+ effects.

Adenosine Triphosphate↗
PubMed2001

Detection of protein oxidation in rat-1 fibroblasts by fluorescently labeled tyramine.

Oxidative damage to proteins has been postulated as a major cause of various degenerative diseases including the loss of functional capacity during aging. A prominent target for oxidation by reactive oxygen species (ROS) is the tyrosine residue. Here we present a highly sensitive method for the detection of tyrosyl radical formation in cells. The method is based on the fluorescein-labeled tyrosine analogue, tyramine, which upon oxidation may couple to proteins carrying a tyrosyl radical. Coupling of the probe (denoted TyrFluo) to standard proteins could be induced by generating ROS with horseradish peroxidase/hydrogen peroxide, SIN-1 or with peroxides (cumene or hydrogen peroxide) in combination with a transition metal. TyrFluo added to rat-1 fibroblasts remained outside the cell, whereas the acetylated form (acetylTyrFluo) was membrane-permeable and accumulated in the cell. Exposure of the cells to oxidative stress in the presence of either TyrFluo or acetylTyrFluo gave a cellular labeling characteristic for each probe. Western blot analysis confirmed that each probe labeled a specific set of proteins. This new method for the detection of ROS-induced oxidation of proteins may mimic the tendency of oxidized proteins to form dityrosine bonds.

Acetylation↗
PubMed1994

Transepithelial transport of tyramine across filter-grown MDCK cells via a poly(D-lysine) carrier.

In order to investigate the advantage of using membrane-adsorptive carriers to mediate drug transport across epithelial tissue, we have prepared disulfide- and thioether-linked conjugates of tyramine (tyn) as a model drug to a cationic, nondegradable carrier, poly(D-lysine) (PDL). The transport properties were evaluated using microporous filter-grown Madin-Darby canine kidney (MDCK, strain I) epithelial cells, and we have determined that: (a) the [125I]tyn-SS-PDL conjugate predominantly transported [125I]tyn in the apical-to-basal direction (20-fold greater transport vs. basal-to-apical); (b) [125I]tyn-SS-PDL elicits a 10-fold greater degree of [125I]tyn transport than [125I]tyn-S-PDL, thus demonstrating the importance of the reducible disulfide linkage for [125I]tyn transport to occur; (c) 125I-radioactivity recovered in the basal media was determined to be 95% [125I]tyn-containing small molecules, thus demonstrating the release of [125I]tyn from its PDL carrier; (d) the apical addition of an anionic species, heparin, completely blocks apical-to-basal transport of [125I]tyn, indicating the importance of PDL-mediated binding to the apical membrane for transport to occur; (e) apical-to-basal transport proceeds via non-lysosomal pathways, as lysosomal inactivation by NH4Cl exposure does not inhibit transport, and (f) the addition of a membrane-impermeable inhibitor of disulfide reduction, bisdithionitrobenzoic acid (DTNB), to the apical media inhibits transport by approximately 70%, indicating the importance of apically-localized disulfide reducing reactions for transport of [125I]tyn. Pulse-chase studies indicate that there is no paracellular leakage of conjugate, and the ratio of recycled:membrane-associated:transported [125I]tyn fragment following chase is 4:2:1.

Animals↗
PubMed1992

Clearance from plasma of lymph chylomicrons and chylomicron remnants labelled with 125I-tyramine-cellobiose.

The aims of the present study were to evaluate the metabolism of chylomicrons (CM) and of CM remnants after labelling with radioactive iodine and converting the iodinated CM into remnants in vitro. Lymph CM were radiolabelled with 125I or sham-labelled with 127I by either the ICl procedure or the tyramine-cellobiose (TC) procedure, then injected into rats. The clearance from plasma of the iodinated CM was compared with control non-iodinated lipid-labelled CM. After iodination with ICl, the plasma removal of endogenously labelled CM was significantly different from non-iodinated CM, with increased uptake of CM triacylglycerols by the liver. In contrast, the clearances from plasma and the uptake by organs of radiolabelled lipids of CM iodinated by the TC method (TC-CM) were similar to control CM. About 40% of the label from 125I-TC-CM was insoluble in 50% propan-2-ol, indicating association with CM apolipoprotein B48. Only about 8% of label was lipid soluble, mostly in phosphatidylethanolamine. Radioactivity from 125I-TC-CM injected intravenously in rats was cleared rapidly and by 30 min only 20% remained in plasma, whereas 48% was recovered in the liver. After fractionation of the plasma by density-gradient ultracentrifugation, most label remained associated with d (relative density) less than 1.006 lipoproteins. In intact rats label was also found associated with the low-density and high-density lipoprotein fractions of plasma. When the liver was excluded from circulation, the recovery of label in low-density- and high-density-lipoprotein fractions was greatly decreased. CM remnants were prepared in vivo by injecting 125I-TC-CM into functionally hepatectomized donors and compared with remnants prepared in vitro by incubation with purified bovine milk lipoprotein lipase. Although remnants prepared in vitro cleared from plasma slower than remnants prepared in vivo, the size, lipid composition and apolipoprotein profile on gradient PAGE of the remnants were similar. We conclude that labelling of CM by the TC method avoided the 'artefactual' changes in metabolism seen after labelling by the ICl procedure. CM remnants when prepared in vitro using lipoprotein lipase were found to be similar to those prepared in vivo after injection into functionally hepatectomized rats.

Animals↗
PubMed2003

B96Bom encodes a Bombyx mori tyramine receptor negatively coupled to adenylate cyclase.

A cDNA encoding a biogenic amine receptor (B96Bom) was isolated from silkworm (Bombyx mori) larvae, and the ligand response of the receptor stably expressed in HEK-293 cells was examined. Tyramine (TA) at 0.1-100 micro m reduced forskolin (10 micro m)-stimulated intracellular cAMP levels by approximately 40%. The inhibitory effect of TA at 1 micro m was abolished by yohimbine and chlorpromazine (each 10 micro m). Although octopamine (OA) also reduced the cAMP levels, the potency was at least two orders of magnitude lower than that of TA. Furthermore, unlabelled TA (IC50 = 5.2 nm) inhibited specific [3H]TA binding to the membranes of B96Bom-transfected HEK-293 cells more potently than did OA (IC50 = 1.4 micro m) and dopamine (IC50 = 1.7 micro m). Taken together with the result of phylogenetic analysis, these findings indicate that the B96Bom receptor is a B. mori TA receptor, which is negatively coupled to adenylate cyclase. The use of this expression system should facilitate physiological studies of TA receptors as well as structure-activity studies of TA receptor ligands.

Adenylyl Cyclases↗
PubMed1974

Decarboxylation to tyramine: a major route of tyrosine metabolism in mammals.

Metabolism of tyrosine was examined in mice, some of which had been treated with an inhibitor of aromatic-L-amino-acid decarboxylase. The results of the study indicate that as the plasma and tissue levels of tyrosine are elevated, decarboxylation to tyramine becomes the predominant route of metabolism. At the highest dose of tyrosine used (1.5 g/kg), it was found that 42% of the administered dose was decarboxylated within 6 hr and only 11.5% was metabolized by the tyrosine aminotransferase pathway.

Animals↗
PubMed1992

Effect of age on potassium- and tyramine-induced release of norepinephrine from cardiac synaptosomes in male F344 rats.

Potassium (K+)-induced norepinephrine (NE) release was examined in preparations of cardiac synaptosomes and sliced atria from 6-, 24-, and 26-mo-old male F344 rats. Cardiac synaptosomes were prepared from rat hearts by collagenase digestion followed by homogenization in 0.32 M sucrose and centrifugation. The synaptosome preparations and the sliced atria were labeled with 3H-NE and then placed in a superfusion system. K(+)-induced net fractional release of NE from synaptosomes prepared from 24- and 26-mo-old rats (4.3% and 3.0%, respectively) was significantly reduced when compared to NE release from synaptosomes from 6-mo-old rats (5.2%). K(+)-induced NE release from sliced atria from 24-mo-old rats (4.7%) was also significantly reduced when compared to NE release from atria from 6-mo-old rats (6.3%). Perfusion of cardiac synaptosomes with buffer prepared without calcium (CA++free, < 5 microM) reduced K(+)-induced release by 50% in all age groups studied. Perfusion with tyramine induced identical rates of NE release from cardiac synaptosomes prepared from 6- and 24-mo-old rats. These results confirm that depolarization-induced NE release from cardiac sympathetic nerves is reduced in the old male F344 rat.

Adrenergic Fibers↗
PubMed1979

Photosensitized formation of thymine dimers in DNA by tyramine, tyrosine and tyrosine-containing peptides.

The formation of Thy-Thy in DNA in the presence of tyramine, tyrosine and tyrosine-containing peptides such as Lys-Tyr and Lys-Tyr-Lys was studied with monochromatic UV irradiation. The formation of Thy-Thy by UV irradiation was enhanced in the presence of these compounds. The action spectrum of the photosensitization has a peak near 280 nm corresponding to the absorption spectrum of tyrosine. The triplet quencher reduced the sensitization substantially. The sensitization in native DNA was more than six times larger than that in denatured DNA. increasing the concentration of salts suppressed the sensitization. The nature of the interaction between DNA and the sensitizer is discussed.

Butadienes↗
PubMed2001

Induction of hydroxycinnamoyl-tyramine conjugates in pepper by Xanthomonas campestris, a plant defense response activated by hrp gene-dependent and hrp gene-independent mechanisms.

Inoculation of pepper leaves, Capsicum annuum cv. Early Calwonder ECW 10R, with strains of Xanthomonas campestris led to an accumulation of the phenolic conjugates feruloyltyramine (FT) and p-coumaroyltyramine (CT) 24 h postinoculation in nonhost- and gene-for-gene-determined incompatible interactions with X. campestris pv. campestris and X. campestris pv. vesicatoria, respectively. In contrast, neither compound was detected in compatible interactions with X. campestris pv. vesicatoria. The accumulation of FT and CT was preceded by an increase in the extractable activity of tyrosine decarboxylase as well as increases in the transcription of genes encoding phenylalanine ammonia-lyase and tyramine hydroxycinnamoyl transferase. No such changes were detected in compatible interactions. Very rapid accumulation of FT and CT occurred (4 h postinoculation) in pepper in response to a X. campestris pv. campestris mutant carrying a deletion of the hrp gene cluster. In contrast, hrp mutants of X. campestris pv. vesicatoria failed to elicit the production of FT and CT. These observations suggest the existence of hrp gene-dependent and -independent activation mechanisms of a defense response involving hydroxycinnamoyltyramines.

Anti-Bacterial Agents↗