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Amaryllidaceae alkaloids (AAs) are plant‐derived natural compounds with diverse bioactivities. To biosynthesize AAs, 4′‐O‐methylnorbelladine (4′‐MB) is a key precursor that is first formed by C–N coupling between tyramine and 3,4‐dihydroxybenzaldehyde catalyzed by a NADPH‐dependent reductase. However, 3,4‐dihydroxybenzaldehyde is oxygen sensitive and not stable due to its catechol moiety when constructing an in vitro enzymatic system for 4′‐MB synthesis. To address this issue, we design an artificial biosynthetic route to synthesize 4′‐MB. First, we choose isovanillin instead of 3,4‐dihydroxybenzaldehyde as an alternative substrate. Then, a short‐chain dehydrogenase/reductase (SDR) from Zephyranthes treatiae is utilized to couple tyramine and isovanillin. After demonstrating the synthesis of 4′‐MB, we optimize the whole biocatalytic system with enhanced performance. The final enzymatic system can be reused for multiple cycles with the help of a crystalline inclusion protein (CipB)‐mediated enzyme immobilization. Additionally, we scale up the reaction system from 50 µL to 10 mL, generating approximately 800 µM of 4′‐MB. We envision that our work will provide an efficient and sustainable approach to produce 4′‐MB, which could support the large‐scale production of Amaryllidaceae plant‐originated natural products. [ABSTRACT FROM AUTHOR]

The quantification of tyramine (Tyr) and spermidine (Spd) is essential to protect and ensure quality and safety for food and beverage consumers. In this work, an electrochemical study was carried out, and a new, rapid, sensitive, reliable, and selective square‐wave voltammetric method for simultaneously determining Tyr and Spd in wines was developed. A Chemically Modified Carbon Paste electrode with Zinc PhthaloCyanine (CMCPE‐ZnPC) was used as a sensor in the electrochemical study, and a standard addition procedure (SAP) was employed to solve the matrix effect in the quantification of Tyr and Spd in wines. These analytes were electroactive on the stable, sensitive, and selective CMCPE‐ZnPC sensor under study using SWV technique, displaying peak anodic potentials at around 400 mV for Tyr and 860 mV for Spd. Wine samples were analyzed using the proposed and reference methods. No statistically significant differences were observed among the results obtained for Tyr and Spd determinations, applying the paired t‐test at a confidence level of 95 %. The proposed method yielded low limits of detection (6.8 nmol L−1 for Tyr and 10.8 nmol L−1 for Spd), good recovery rates (from 86.1 to 107.5 %), and reproducibility (overall RSD of 2.6 %). The proposed method contributes to green analytical chemistry since it uses no chemical pretreatment of the wine samples. [ABSTRACT FROM AUTHOR]

Guided by the idea that the presence of a heterocyclic aromatic core and tyramine moiety, under the umbrella of a single molecular scaffold could bring interesting biological properties, herein we present synthesis, characterization, with two crystal structures reported, and biological evaluation of some tyramine derivates. Cytotoxic and antimigratory potential was addressed by using a colorectal cancer cell line as a model system. Although possessing no cytotoxic effects, two compounds have shown strong antimigratory potential in low doses, with no effect on healthy MRC‐5 cells. Evaluation of their antimicrobial activities suggested prominent antimicrobial activity, where Compound 4 outperformed streptomycin against Escherichia coli and Proteus mirabilis. Hormone‐dependent types of cancer, such as prostate, ovary, and breast, are highly dependent on human sex hormone–binding globulin (SHBG) blood levels. A molecular docking study has shown that 1 has high affinity to bind and therefore compete with natural steroids for the SHBG steroid‐binding site. DNA‐binding study have shown that 4 interacts with CT‐DNA in a groove‐binding mode. In silico ADME/T study revealed that all compounds have suitable physicochemical properties for oral bioavailability and druglikeness, while toxicity tests for 1, 4, and 6 suggested potential for mutagenicity (4, 6), hepatotoxicity (6), and skin sensation (1). [ABSTRACT FROM AUTHOR]

Summary: Impacts of aqueous and ethanolic extracts of garlic were investigated in suppressing bacterial growth and biogenic amine (BA) formation by selected foodborne pathogens (Candida albicans, Salmonella paratyphi A, Escherichia coli and Staphylococcus aureus) and fish spoilage bacteria (Enterococcus faecalis, Photobacterium damselae and Pseudomonas luteola). The spread‐plate method was used to monitor bacterial growth in histidine decarboxylase broth (HDB), whereas the rapid high‐performance liquid chromatographic (HPLC) method was used for BA analysis. Bacterial growth and their ammonia and BA production were monitored using HDB. The results showed that bacterial growth on HDB was in the range from 9.13, for P. luteola, to 9.54 log CFU (colony‐forming units) mL−1, for S. aureus and C. albicans. The presence of garlic extracts in HDB resulted considerably in lowering bacterial growth and BA formation (P < 0.05). The highest inhibitory activities of ethanolic and water garlic extracts were obtained for Gram‐positive S. aureus with 1.4 and 1.5 logarithmic reduction on bacterial growth, followed by Gram‐negative Salmonella Paratyphi A and E. coli. Application of garlic extracts, mainly ethanolic ones, showed a significant inhibitory effect on bacterial ammonia production, with 4‐100‐fold lower ammonia accumulation (P < 0.05). Bacteria produced all tested BAs, mainly dopamine, agmatine and tryptamine. The highest levels of histamine and tyramine (61.99 and 36.45 mg L−1) were produced by S. aureus. In the presence of aqueous or ethanolic garlic extracts, putrescine production by E. faecalis was around 110‐fold lower than that of the control group. Results revealed that both garlic extracts are potent antimicrobials that can control the growth of foodborne pathogens and their harmful BA formation. [ABSTRACT FROM AUTHOR]

This study has performed molecular modeling, vibrational dynamics, and thermodynamics of tyramine neurotransmitter and its monohydrate cluster in gas phase. All theoretical calculations for tyramine and its monohydrate cluster are performed at DFT/B3LYP/6‐31++G(d,p) level to optimize the electronic structures and calculation of vibrational frequencies. Most of the vibrational frequencies have been found in good agreement with the experimentally reported IR and Raman frequencies. However, some have been modified. The presence of water monomer decreased highest molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap of tyramine by 0.07 eV. Themodynamics calculations reveal that thermal energy and specific heats in both the tyramine and its monohydrate clusters are predominantly contributed by vibrational motions while entropy shows only 28% and 26% vibrational contribution in tyramine and its monohydrate cluster, respectively. [ABSTRACT FROM AUTHOR]

This study aimed at investigating the quality attributes of Turkish fermented sausage (sucuk) incorporated with bay leaf extract obtained as a natural antioxidant and a source of phytochemicals. Five different bay leaf extracts were obtained with distilled water and 60%, 70%, 80%, and 90% ethanol. The total phenolic contents and antioxidant activity values indicated that ultrasound‐assisted 70% ethanol extract was the most suitable extract. Furthermore, five groups of sucuks were manufactured with the addition of bay leaf extract (1, 5, and 10 mL/kg), ascorbic acid (500 mg/kg), and control. The extracts were produced similar pH values when compared to control and ascorbic acid samples. The treatments had no significant effect on moisture contents of sucuks. Bay leaf extracts produced comparable color, texture profile analysis, and TBARS values to control and ascorbic acid samples. Biogenic amine contents (mg/kg dry weight) of sucuks including tryptamine (6.43–30.66), 2‐phenylethylamine (2.24–32.04), putrescine (2.19–7.98), cadaverine (3.28–12.21), histamine (7.01–11.38), tyramine (3.27–71.07), spermidine (4.44–8.01), and spermine (53.96–68.25) were mostly within the lower ranges typically associated with sucuk. However, the lowest cadaverine values observed at the end of storage in the bay leaf extract added samples indicated that bay leaf extract might be effective in decreasing cadaverine values during storage. The addition of bay leaf extract caused similar sensory attributes to the control and ascorbic acid samples. This study revealed that Turkish fermented sucuks could be effectively incorporated with bay leaf extracts without a negative effect on the quality attributes or consumer acceptability. [ABSTRACT FROM AUTHOR]

Summary: Cheese is a fermented food in which toxic concentrations of biogenic amines (BAs) may accumulate, mainly as a result of the metabolism of certain lactic acid bacteria (LAB); the formation of these compounds needs to be limited. This work reports the antimicrobial potential of bacteriocin AS‐48 against the LAB largely responsible for the accumulation of the BA histamine, tyramine and putrescine in cheese. Most of the 50 analysed BA‐producing LAB strains were sensitive to AS‐48. The bacteriocin also prevented biofilm formation of 92% of the BA‐producing strains tested. This result is of great technological importance since, in cheese production, biofilms are an important source of contamination by BA‐producing LAB. This study supports the potential use of AS‐48 as a biopreservative for controlling BA‐producing LAB in fermented food. [ABSTRACT FROM AUTHOR]

The oral tyramine challenge evaluates the safety of novel monoamine oxidase (MAO) inhibitors when taken with tyramine‐containing food or drinks. In its current design, it comprises an extensive series of tyramine escalation steps until a blood pressure threshold is met. Due to the high variation in tyramine bioavailability, and thereby in blood pressure effect, this classical design has various limitations, including safety concerns. Based on data from a previously performed tyramine challenge study, the present study explored a reduced new design that escalates up to 400 mg, and evaluates the dose to a tyramine peak plasma concentration of ≥10 ng/mL, instead of a dose up to 800 mg, and to a blood pressure change of ≥30 mm Hg. Tested by trial simulation, the new design proves more efficient than the classical design in terms of better identifying tyramine sensitivity of test and reference treatments and reducing false‐positive and false‐negative rates in estimating tyramine sensitivity by more than 10‐fold. Since it escalates over a lower tyramine dose range, the new design reduces risk to subjects associated with tyramine‐induced blood pressure excursions, is less demanding for study participants, and is more efficient. By its focus on tyramine bioavailability as the primary concern for novel MAO inhibitors, the new tyramine challenge study provides better answers in a simplified and safer design compared with the classical design in trial simulation, warranting its use in future clinical studies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mating and oviposition are essential and closely coordinated events in the reproduction of moths. Although tyramine, a biogenic amine, can affect insect reproduction by binding its receptors, the specific regulatory mechanism has not yet been fully elucidated. RESULTS: Plutella xylostella mutant with tyramine receptor 1 (TAR1) knockout (homozygous mutant with 7‐bp deletion, Mut7) was developed by the CRISPR/Cas9 system to investigate the effect of TAR1 knockout on the reproduction of the moth. Compared with wild‐type (WT), the egg yield of Mut7 female (Mut7F) was significantly lower, no significant difference was observed in the egg size and hatching ratio between the groups. Further analysis showed that TAR1 knockout adversely affected ovary development, characterized by shorter ovarioles and fewer mature oocyte. Additionally, TAR1 knockout significantly reduced the occurrence of mating, resulting in a decrease in egg yield in Mut7F. The amounts of sex pheromones were quantified using gas chromatography–mass spectrometry. Results showed that the amounts of sex pheromone released by Mut7F were significantly lower before mating. Correspondingly, the messenger RNA (mRNA) levels of sex pheromone biosynthesis enzymes, including acetyl‐CoA carboxylase (ACC) and desaturase (DES), were significantly lower in the Mut7F pheromone gland. The decreased sex pheromone biosynthesis in Mut7F, especially before re‐mating, may be related to the underexpression of pheromone biosynthesis‐activated neuropeptide (PBAN). CONCLUSION: Overall, this study investigated the effect of PxTAR1 on oviposition and mating of P. xylostella. We report for the first time that TAR1 knockout could reduce the sex pheromone biosynthesis. These findings provide insights for developing a novel integrated pest control strategy based on mating interference. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Most Chilean red wine is produced by spontaneous malolactic fermentation (MLF), which generates prolonged fermentations resulting in uncertain results, increase production cost, and lead to biogenic amine (BA) formation. The objective of this work was to carry out a preliminary study of an autochthonous MLF starter culture to perform shorter and controlled MLF to elaborated red wines with low BA content. The autochthonous Oenococcus oeni strain (OoB6) isolated from spontaneous MLF was assayed in bioreactors using filtered and unfiltered wines. OoB6 strain efficiently carried out MLF samples showing a similar performance to commercial starter culture. Both accomplished malic acid concentrations (<0.12 g/L) significantly lower (p <.05) than the initial content (1.21 ± 0.11 g/L). OoB6 strain produced a 50% reduction in MLF time and showed very low BA formation (ca. 5 mg/L) without detecting the presence toxicological important BA histamine and tyramine. Novelty impact statement: To the best of our knowledge, this work report for the first time a preliminary study of potential autochthonous MLF starter culture to elaborate Chilean red wines.Autochthonous MLF starter culture produced a 50% reduction in MLF time compared with traditional spontaneous MLF.Autochthonous MLF starter culture showed very low BA formation (ca. 5 mg/L) without detecting the presence toxicological important BA histamine and tyramine. [ABSTRACT FROM AUTHOR]

Tyramine (TYM) is catecholamine releasing compound and TYM rich food causes hypertensive crisis due to a combination with monoamine oxidase inhibitor (MAOIs). Therefore, analysis of TYM in TYM rich food as (old cheese, cured meat, sausage, pickled olive and canned fish) and the environment is essential for hypertensive patients and to improvement of food industries. In this work, TYM was analyzed in different types of food using novel green synthesis carbon dots from Ficus carica (fig fruits). The gradual addition of TYM to polyamine carbon quantum dots (PA@CQDs) led to enhancement of the quantum dots fluorescence due to formation of hydrogen bonding between quantum dots and TYM. The calibration graph was plotted in the range 5–400 ng mL−1. The method was applied for the determination of TYM in different types of food as old cheese, cured meat, sausage, pickled olive and canned fish. The lower limit of quantitation (LOQ) was found to be 1.68 ng mL−1. The method was successfully applied for the quantification of TYM in varying types of food with high sensitivity and high economic effect due to the reusability of the quantum dots. The optical and morphological characters of quantum dots were studied carefully. [ABSTRACT FROM AUTHOR]

Sanchuan ham, produced in Yunnan, China, is food with ethnic characteristics favored by consumers. However, it can contain biogenic amines such as tyramine that are harmful to health, and the synthesis mechanism of biogenic amines in Sanchuan ham is not clear. This study focuses on the regulation of biogenic amine synthesis by quorum sensing. We used high‐performance liquid chromatography to detect the content of biogenic amine in different kinds of ham and found that the content of biogenic amine in Sanchuan ham was higher than that in others. Tyramine‐producing strain isolated from Sanchuan ham was identified as Enterococcus faecium. By monitoring the growth and tyramine synthesis of Enterococcus faecium under cultured conditions, the results found that high temperature and low salt increased tyramine production by E. faecium. After seven exogenous amino acids were applied to E. faecium, only tyrosine could promote the production of tyramine in E. faecium, and tyramine could not be synthesized in E. faecium until a certain amount was reached, indicating the presence of microbial quorum sensing signal molecules in the synthesis of tyramine in E. faecium. Untargeted metabolomics analysis of the differential metabolites produced by E. faecium showed that the contents of some peptides, especially alanyl‐leucine, were significantly increased. Further experiments with synthetic alanyl‐leucine illustrated that alanyl‐leucine activated the expression of tyrosine decarboxylase (tyrDC), thereby regulating the synthesis of tyramine by E. faecium. Alanyl‐leucine acted as quorum sensing signal molecules for biogenic amine synthesis by E. faecium, which provided a theoretical basis for reducing biogenic amine accumulation in ham. It is beneficial to control the content of biogenic amines in ham in the future. [ABSTRACT FROM AUTHOR]

Exploratory data analysis was used to evaluate the influence of NaCl concentration on the relation between endogenous microbiota (mesophilic aerobic bacteria, psychrotrophic bacteria, lactic acid bacteria, Enterobacteriaceae and Staphylococcus spp.) and biogenic amines (BAs) (histamine, tyramine, putrescine, cadaverine and spermidine) content in Brazilian dry‐cured loin (BDL). Using hierarchical cluster analysis (HCA), initial data analysis led to samples separation into a higher and a lower NaCl cluster. The analysis of variance showed that the microbial counts did not differ between the clusters (p > 0.05). However, the higher NaCl cluster showed a lower level of BAs. Further, principal component analysis (PCA) demonstrated a negative correlation between the microbial counts and BAs content in the lower NaCl cluster, thus indicating the possibility of the higher BA's content in the lower NaCl cluster being a result of a stress–response mechanism. On the other hand, in the higher NaCl cluster, the salt concentration had an inhibitory property in BA's formation except for histamine. The collective results point to a NaCl threshold to minimise the production of BAs in BDL. The findings of the present exploratory study highlight the possibility of intervention for BA minimization without the need for designed starter cultures or preservation treatments. [ABSTRACT FROM AUTHOR]

The fermentation process is the main formation source of biogenic amines in cheese. The other conditions, like enzymatic reaction, starter culture, temperature, period of maturation, milk treatment, the amount of proteolysis, oxygen, water activity, humidity and pH, can change the rate of the formation of biogenic amines. Tyramine has been defined as quality index for dairy products like cheese. In this work, we have successfully employed the advanced hollow‐fibre electromembrane extraction/dispersive microextraction followed by gas chromatography–mass spectrometry as a rapid and sensitive technique for the determination of biogenic amines including putrescine, tyramine, histamine and cadaverine in Lighvan cheese samples. [ABSTRACT FROM AUTHOR]

A system capable of photoreleasing tyramine has been developed. The photodonor system consists of an isoindole cage of tyramine and a biscyclometalated Ir(III) complex singlet oxygen (1O2) photosensitizer. Photoirradiation at a wavelength of 365 nm produces tyramine, as evidenced by mass spectrometry and 1H NMR spectroscopy. The photorelease proceeds through two steps involving the formation of a Diels–Alder‐type [2 + 4] cycloadduct of 1O2, followed by the slow and spontaneous decomposition of the adduct into tyramine and 2‐benzoylbenzophenon. [ABSTRACT FROM AUTHOR]

The physicochemical properties, color characteristics, and biogenic amine (BA) concentrations of Konya Green cheese during ripening process with mold were investigated. Four productions were made in different periods, and the samples were analyzed at the end of the cold storage period (0) and on days 1, 3, 7, 15, 21, 24, and 30 of mold ripening. It was found that dry matter, acidity, and salt values tend to increase, whereas pH and aw values tend to decrease during the mold ripening period in all production groups. Total BA content increased significantly from 70.91 to 136.95 mg/kg during the ripening period (p <.01). Principal components explained 92.5% of the total variation among the four production group cheese. Based on the Hierarchical clustering analysis, three clusters were obtained: 1st (0, 3, 15), 2nd (1, 24, 30), and 3rd (7, 21). Tyramine, cadaverine, putrescine, and histamine were observed in 2nd cluster as per the PCA. Novelty impact statement: The biogenic amine formation and dominancy of the principal biogenic amins through ripening period of Konya Green cheese were determined using RP‐HPLC. The predominant biogenic amines determined at the end of the ripening time were tyramine, cadaverine, and putrescine which represent around 81% of the total BA present. To the best of our knowledge, this is the first study for determinig the biogenic amin production of Konya Green cheese. [ABSTRACT FROM AUTHOR]

Identifying mechanisms underlying alcohol‐related behaviors could provide important insights regarding the etiology of alcohol use disorder. To date, most genetic studies on alcohol‐related behavior in model organisms have focused on neurons, leaving the causal roles of glial mechanisms less comprehensively investigated. Here, we report our studies on the role of Tyrosine decarboxylase 2 (Tdc2), which converts tyrosine to the catecholamine tyramine, in glial cells in Drosophila alcohol sedation. Using genetic approaches that drove transgene expression constitutively in all glia, constitutively in astrocytes and conditionally in glia during adulthood, we found that knockdown and overexpression of Tdc2, respectively, increased and decreased the sensitivity to alcohol sedation in flies. Manipulation of the genes tyramine β‐hydroxylase and tyrosine hydroxylase, which respectively synthesize octopamine and dopamine from tyramine and tyrosine, had no discernable effect on alcohol sedation, suggesting that Tdc2 affects alcohol sedation by regulating tyramine production. We also found that knockdown of the vesicular monoamine transporter (VMAT) and disruption of the SNARE complex in all glia or selectively in astrocytes increased sensitivity to alcohol sedation and that both VMAT and the SNARE complex functioned downstream of Tdc2. Our studies support a model in which the synthesis of tyramine and vesicle‐mediated release of tyramine from adult astrocytes regulates alcohol sedation in Drosophila. Considering that tyramine is functionally orthologous to norepinephrine in mammals, our results raise the possibility that gliotransmitter synthesis release could be a conserved mechanism influencing behavioral responses to alcohol as well as alcohol use disorder. [ABSTRACT FROM AUTHOR]

The effect of ε‐polylysine hydrochloride (ε‐PL) and thymol (TY) in the changes of biogenic amines (BAs) and the quality properties of Illex argentinus was evaluated by measuring the content of BAs, total viable count (TVC), pH, sensory score, and odor change. The experiment was divided into four groups, the control, ε‐PL, TY, and the compound (ε‐PL–TY) group. The results showed BAs‐producing bacteria contained Enterobacteriaceae bacterium, Citrobacter braakii, Klebsiella pneumoniae, Obesumbacterium proteus, Hafnia alvei, Hafnia paralvei, and Hafnia alvei sensu. ε‐PL, TY, and ε‐PL–TY effectively inhibited the increase of BAs content, TBA, pH, and maintained the fresh flavor and sensory properties. ε‐PL–TY was the best to reduce the content of phenethylamine, putrescine, cadaverine, and tyramine by 45.11%, 79.08%, 72.92%, and 63.53% compared with the control at the end of storage. ε‐PL–TY was a promising BAs inhibitor that could protect the edible value and safety of aquatic products. Practical applications: Illex argentinus is susceptible to corruption, and then microorganism in Illex argentinus will produce several biogenic amines, while the combined preservative is the most convenient way to protect its quality after postmortem. Although ε‐polylysine hydrochloride has a better antibacterial activity as a preservative, the single preservative cannot exert a better effect. Thymol is a natural plant ingredient with great antioxidant properties and antibacterial activities, which had an inhibitory synergy with ε‐PL in this study. ε‐polylysine hydrochloride– thymol could be a promising preservative to control the biochemistry activities and protect the edible value of squid. [ABSTRACT FROM AUTHOR]

Regulation of pollen and nectar foraging in honeybees is linked to differences in the sensitivity to the reward. Octopamine (OA) participates in the processing of reward‐related information in the bee brain, being a candidate to mediate and modulate the division of labour among pollen and nectar foragers. Here we tested the hypothesis that OA affects the resource preferences of foragers. We first investigated whether oral administration of OA is involved in the transition from nectar to pollen foraging. We quantified the percentage of OA‐treated bees that switched from a sucrose solution to a pollen feeder when the sugar concentration was decreased experimentally. We also evaluated if feeding the colonies sucrose solution containing OA increases the rate of bees collecting pollen. Finally, we quantified OA and tyramine (TYR) receptor genes expression of pollen and nectar foragers in different parts of the brain, as a putative mechanism that affects the decision‐making process regarding the resource type collected. Adding OA in the food modified the probability that foragers switch from nectar to pollen collection. The proportion of pollen foragers also increased after feeding colonies with OA‐containing food. Furthermore, the expression level of the AmoctαR1 was upregulated in foragers arriving at pollen sources compared with those arriving at sugar‐water feeders. Using age‐matched pollen and nectar foragers that returned to the hive, we detected an upregulated expression of a TYR receptor gene in the suboesophageal ganglia. These findings support our prediction that OA signalling affects the decision in honeybee foragers to collect pollen or nectar. [ABSTRACT FROM AUTHOR]

A commercial fava bean protein isolate and a liquid nutritional product formulated with it were tested by validated HPLC methods for the favism-associated pyrimidine glycoside vicine, the dopamine precursor levodopa, and the biogenic amine tyramine. The vicine, levodopa, and tyramine concentrations in the protein isolate—306, 13.3, and <0.5 mg/kg, respectively—when expressed on a protein basis—34, 1.5, and <0.06 mg/100 g protein, respectively—were at least 96% lower than the vicine, levodopa, and tyramine (protein-based) concentrations reported for fava beans (≥900, ~200, and ~4 mg/100 g protein, respectively). This was also true for the vicine (13 mg/kg or 22 mg/100 g protein), levodopa (≤0.17 mg/kg or ≤0.3 mg/100 g protein), and tyramine (0.08 mg/kg or 0.14 mg/100 g protein) concentrations in the nutritional product. On the basis of these data, one serving (11 fl. oz.) of the nutritional product would deliver approximately 5 mg of vicine, <1 mg of levodopa, and <0.1 mg of tyramine. [ABSTRACT FROM AUTHOR]

A comparison of the analytical characteristics of two tyramine biosensors, based on graphene oxide (GRO) and polyvinylferrocene (PVF) modified screen‐printed carbon electrodes (SPCE), is reported. Diamine oxidase (DAOx) or monoamine oxidase (MAOx) was immobilized onto the PVF/GRO modified SPCE to fabricate the biosensors. Surface characteristics and electrochemical behaviour of the modified SPCEs were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and cyclic voltammetry (CV). Electrode surface composition and experimental variables such as pH and working potential were optimized in order to ensure a high performance. Under optimum experimental conditions, both DAOx/PVF/GRO/SPCE and MAOx/PVF/GRO/SPCE biosensors exhibited wide linear dynamic ranges for tyramine from 9.9×10−7 to 1.2×10−4 M and from 9.9×10−7 to 1.1×10−4 M, respectively. MAOx/PVF/GRO/SPCE biosensor showed higher sensitivity (11.98 μA mM−1) for tyramine determination than the DAOx/PVF/GRO/SPCE biosensor (7.99 μA mM−1). The substrate specifity of the biosensors to other biogenic amines namely histamine, putrescine, spermine, spermidine, tryptamine, β‐phenylethylamine and cadaverine was also investigated. The developed biosensors were successfully used for tyramine determination in cheese sample. [ABSTRACT FROM AUTHOR]

Summary: Enzyme promiscuity, a common property of many uridine diphosphate sugar‐dependent glycosyltransferases (UGTs) that convert small molecules, significantly hinders the identification of natural substrates and therefore the characterization of the physiological role of enzymes. In this paper we present a simple but effective strategy to identify endogenous substrates of plant UGTs using LC‐MS‐guided targeted glycoside analysis of transgenic plants. We successfully identified natural substrates of two promiscuous Nicotiana benthamiana UGTs (NbUGT73A24 and NbUGT73A25), orthologues of pathogen‐induced tobacco UGT (TOGT) from Nicotiana tabacum, which is involved in the hypersensitive reaction. While in N. tabacum, TOGT glucosylated scopoletin after treatment with salicylate, fungal elicitors and the tobacco mosaic virus, NbUGT73A24 and NbUGT73A25 produced glucosides of phytoalexin N‐feruloyl tyramine, which may strengthen cell walls to prevent the intrusion of pathogens, and flavonols after agroinfiltration of the corresponding genes in N. benthamiana. Enzymatic glucosylation of fractions of a physiological aglycone library confirmed the biological substrates of UGTs. In addition, overexpression of both genes in N. benthamiana produced clear lesions on the leaves and led to a significantly reduced content of pathogen‐induced plant metabolites such as phenylalanine and tryptophan. Our results revealed some additional biological functions of TOGT enzymes and indicated a multifunctional role of UGTs in plant resistance. Significance Statement: Nicotiana species produce numerous bioactive glycosylated metabolites using promiscuous uridine diphosphate (UDP)‐sugar‐dependent glycosyltransferases whose in planta substrates and detailed functions are difficult to identify. In this paper we show that the orthologous proteins of a previously identified scopoletin glucosyltransferase from Nicotiana tabacum glucosylate the phytoalexin N‐feruloyl tyramine in Nicotiana benthamiana, which consequently also reduces the concentrations of other pathogen‐responsive metabolites and therefore influences plant defence. [ABSTRACT FROM AUTHOR]

An amperometric tyramine biosensor based on poly‐L‐lysine (PLL) and Fe3O4 nanoparticles (Fe3O4NP) modified screen printed carbon electrode (SPCE) was developed. PLL was formed on the SPCE by the electropolymerization of L‐lysine. Subsequently, Fe3O4NP suspension prepared in chitosan (CH) solution was casted onto the PLL/SPCE. Tyrosinase (Ty) enzyme was immobilized onto the modified Fe3O4−CH/PLL/SPCE and the electrode was coated with Nafion to fabricate the Ty/Fe3O4−CH/PLL/SPCE. Different techniques including scanning electron microscopy, chronoamperometry (i–t curve), cyclic voltammetry and electrochemical impedance spectroscopy were utilized to study the fabrication processes, electrochemical characteristics and performance parameters of the biosensor. The analytical performance of the tyramine biosensor was evaluated with respect to linear range, sensitivity, limit of detection, repeatability and reproducibility. The response of the biosensor to tyramine was linear between 4.9×10−7–6.3×10−5 M with a detection limit of 7.5×10−8 M and sensitivity of 71.36 μA mM−1 (595 μA mM−1 cm−2). The application of the developed biosensor for the determination of tyramine was successfully tested in cheese sample and mean analytical recovery of added tyramine in cheese extract was calculated as 101.2±2.1 %. The presented tyramine biosensor is a promising approach for tyramine analysis in real samples due to its high sensitivity, rapid response and easy fabrication. [ABSTRACT FROM AUTHOR]

Summary: Tyramine has been considered a biological hazard for foods and beverages. In this study, an ultra‐high pressure liquid chromatography (UPLC) with benzylamine as an internal standard in dansyl chloride pre‐column derivatisation was developed to determine tyramine in various foods. Different from other tyramine determination methods usually without an internal standard in the pre‐column derivatisation, benzylamine which chemical structure is similar to tyramine was selected as an internal standard. The limits of detection and quantification of this method were 0.05 and 0.25 mg L−1, respectively, while the relative standard deviations of repeatability and reproducibility were 2.1% and 3.1%, respectively. The sensitivity and reliability of this method were also evaluated by determining tyramine in common liquid, pasty and solid foods. The recoveries of tyramine in these foods were between 87.3% and 96.8% by using this method. Overall, it is a fast, inexpensive, reliable and sensitive method to measure tyramine in different food products. [ABSTRACT FROM AUTHOR]

We report here a photodissociation study of tyramine, tryptamine and histamine using the customized time‐of‐flight mass spectrometer (TOF‐MS) combined deep ultraviolet laser ionization. The cleavage of Cα‐Cβ bond, free of hydrogen atom transfer (HAT), is observed under the 177 nm DUV laser excitation, which is different from the HAT‐involved photodissociation by a 118 nm vacuum ultraviolet (VUV) laser. With aid of density function theory (DFT) calculations, we demonstrate the photochemical reaction mechanism of these neurotransmitter molecules with dependence on residual energies after photoionization and donor‐acceptor orbital interactions. This finding helps to enrich the understanding of structure chemistry of neurotransmitters. In particular, the brittle fracture of Cα‐Cβ bond initiated by the ultrafast DUV laser could stimulate research interest in designed synthesis of organic compounds. [ABSTRACT FROM AUTHOR]

Animals must effectively balance the time they spend exploring the environment for new resources and exploiting them. One way that social animals accomplish this balance is by allocating these two tasks to different individuals. In honeybees, foraging is divided between scouts, which tend to explore the landscape for novel resources, and recruits, which tend to exploit these resources. Exploring the variation in cognitive and physiological mechanisms of foraging behaviour will provide a deeper understanding of how the division of labour is regulated in social insect societies.Here, we uncover how honeybee foraging behaviour may be shaped by predispositions in performance of latent inhibition (LI), which is a form of non‐associative learning by which individuals learn to ignore familiar information.We compared LI between scouts and recruits, hypothesizing that differences in learning would correlate with differences in foraging behaviour. Scouts seek out and encounter many new odours while locating novel resources, while recruits continuously forage from the same resource, even as its quality degrades.We found that scouts show stronger LI than recruits, possibly reflecting their need to discriminate forage quality. We also found that scouts have significantly elevated tyramine compared to recruits. Furthermore, after associative odour training, recruits have significantly diminished octopamine in their brains compared to scouts.These results suggest that individual variation in learning behaviour shapes the phenotypic behavioural differences between different types of honeybee foragers. These differences in turn have important consequences for how honeybee colonies interact with their environment. Uncovering the proximate mechanisms that influence individual variation in foraging behaviour is crucial for understanding the ecological context in which societies evolve. Honeybees have mastered the exploration–exploitation trade‐off by dividing foraging labour. Here, the authors report that underlying this division of labour is variation in learning ability: scouts ignore familiar odours while recruits readily learn novel and familiar odours. Further, scouts and recruits have different quantities of biogenic amines in their brains, influencing their behaviour. [ABSTRACT FROM AUTHOR]

The 2‐step synthesis of [1‐14C]tyramine hydrochloride is described with the product being characterized by TLC, HPLC, and UV spectroscopy. Several methods are provided to purify [1‐14C]tyramine hydrochloride, and its storage and stability are also discussed. The two‐step synthesis of [1‐14C]tyramine hydrochloride is described with the product being characterized by TLC, HPLC, and UV spectroscopy. Several methods are provided to purify [1‐14C]tyramine hydrochloride, and its storage and stability are also discussed. [ABSTRACT FROM AUTHOR]

Alginate‐based hydrogels represent promising microenvironments for cell culture and tissue engineering, as their mechanical and porous characteristics are adjustable toward in vivo conditions. However, alginate scaffolds are bioinert and thus inhibit cellular interactions. To overcome this disadvantage, bioactive alginate surfaces were produced by conjugating tyramine molecules to high‐molecular‐weight alginates using the carbodiimide chemistry. Structural elucidation using nuclear magnetic resonance spectroscopy and contact angle measurements revealed a surface chemistry and wettability of tyramine‐alginate hydrogels similar to standard cell culture treated polystyrene. In contrast to stiff cell culture plastic, tyramine‐alginate scaffolds were found to be soft (60–80 kPa), meeting the elastic moduli of human tissues such as liver and heart. We further demonstrated an enhanced protein adsorption with increasing tyramine conjugation, stable for several weeks. Cell culture studies with human mesenchymal stem cells and human pluripotent stem cell‐derived cardiomyocytes qualified tyramine‐alginate hydrogels as bioactive platforms enabling cell adhesion and contraction on (structured) 2‐D layer and spherical matrices. Due to the alginate functionalization with tyramines, stable cell–matrix interactions were observed beneficial for an implementation in biology, biotechnology, and medicine toward efficient cell culture and tissue substitutes. © 2018 The Authors. Journal of Biomedical Materials Research Part A published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 114–121, 2019. [ABSTRACT FROM AUTHOR]

The detection of biogenic amines is of significant interest to the food industry, as they can be used as indicators of food spoilage and they are potentially toxic. Because of their importance, there is a need for automated methods suitable for industry use that can detect a wide range of biogenic amines at sufficient levels for food analysis. In this work, optimized conditions for the automated determination of biogenic amines (histamine, putrescine, cadaverine, spermine, spermidine, tyramine, and tryptamine) derivatized with dansyl chloride are presented. Limits of detection below 0.2 ppm were achieved for seven biogenic amines and percentage recoveries were between 80 and 109% for the seven analytes spiked into meat meal samples. The method is simple and compared well to an existing method for the detection of biogenic amines in pet food ingredients. [ABSTRACT FROM AUTHOR]

In the past two decades, the solvomorphism phenomenon in organic materials has attracted much attention, especially in the pharmaceutical and materials industries. Cocrystallization with solvent molecules can lead to modified physical and chemical properties of materials. We present here two new solvomorphs (pseudopolymorphs) of tyraminium 5,5‐diethylbarbiturate [2‐(4‐hydroxyphenyl)ethanaminium 5,5‐diethyl‐2,4,6‐trioxotetrahydro‐2H‐pyrimidin‐1‐ide, C8H12NO+·C8H11N2O3−] with unusual structural features. Pseudopolymorph (I) follows the symmetry of the P21/n space group and has four tyraminium cations, four barbitalate anions and four molecules of chloroform in the asymmetric unit. Pseudopolymorph (II) crystallizes in the space group Rc with one tyraminium cation, one barbitalate anion and a small amount of disordered solvent (ethanol and water) located in the cavities. Hirshfeld surface analysis and the Non‐Covalent Interaction (NCI) index were used to examine and compare the crystal packing features and intermolecular interactions in (I) and (II). Both materials crystallize with large unit cells and contain nontypical barbitalate ions formed through deprotonation of the barbital N3 position. Pseudopolymorph (I) is an example of a crystal structure with a rarely observed value of Z′ = 4. Analysis of the hydrogen‐bond patterns in (II) showed an unusual arrangement of three barbitalate anions in R33(12) rings, which is the first example of such a hydrogen‐bond motif in barbital structures. The mutual arrangement of the ions in the crystal structure of (II) leads to the formation of specific cavities along the c direction. A tyraminium barbitalate solvomorph (pseudopolymorph) contains disordered chloroform molecules and its Z′ value is 4. A second solvomorph, a rare example of a crystal structure with a hydrogen‐bonded (12) ring motif, exhibits a layered structure, with cavities containing disordered water and ethanol molecules. [ABSTRACT FROM AUTHOR]

The aim of this study was to characterise the contaminating microorganisms during individual stages of manufacture of quark‐type cheese and also describe their capability of biogenic amine production. We isolated and identified 118 contaminating microorganisms for which the production of biogenic amines has been established. Over half of the isolates were capable of significantly producing at least one biogenic amine and, in some cases, multiple amines (content values for a particular biogenic amine exceeding 200 mg/L of broth). The strongest production ability of the isolated microorganisms was for putrescine and tyramine. [ABSTRACT FROM AUTHOR]

We report here non‐enzymatic electrochemical biosensing of H2O2 using a highly stable, metal‐free, tyramine functionalized graphene (T‐GO) based electrocatalytic system. The surface functionalization of tyramine on graphene was carried out chemically. The obtained sheets were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) as well as X‐ray photoelectron (XP), Raman, FT‐IR and UV‐visible spectroscopy. More significantly, the combined results from morphological and structural studies show the formation of a few layers of graphene with effective large‐scale functionalization by tyramine. As a metal‐free electrocatalyst, the as‐synthesized T‐GO shown good electrocatalytic activity towards reduction of H2O2 with a sensitivity of 0.105 mM/cm2 confirmed by combined results from cyclic voltammetric (CV) and linear sweep voltammetric (LSV), and amperometric (i–t) measurements. The lower onset potential (−0.23 mV vs SCE), lower detection limit, wider concentration range (10 mM to 60 mM) with higher electrochemical current and potential stability demonstrated the potential of our non‐enzymatic and cost‐effective T‐GO based electrocatalytic system towards reduction of hydrogen peroxide. A non‐enzymatic electrochemical biosensor for H2O2 detection is fabricated using tyramine functionalized graphene (T‐GO). As a metal‐free electrocatalyst, T‐GO shows good activity towards reduction of H2O2. A lower onset potential, lower detection limit, wider concentration range with higher electrochemical current and potential stability demonstrates the potential of the T‐GO based system towards reduction of hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Abstract: The electropolymerization of tyramine has been investigated using glassy carbon electrodes modified with six classes of carbon materials, namely carbon black, graphitized carbon, graphite, graphene oxide, chemical vapour deposition based multi‐walled carbon nanotubes and arc discharged based multi‐walled carbon nanotubes. These materials were characterized before and after electrodeposition of polytyramine (PT) by Raman spectroscopy, inductively coupled plasma optical emission spectrometry, cyclic voltammetry and amperometry. Previously, other groups have established that impurities present in carbon materials, can play a critical role in electrocatalytic activity. In this study, the presence of graphitic basal plane carbon, rather than metallic impurities, is believed to initiate the formation of a redox active PT film that mediates the oxidation of NADH. The importance of graphitic basal plane carbon was supported by examining the impact of the graphitization of carbon black over the range of 500 to 2000 °C. Graphitic basal plane carbon impurity was demonstrated to be highly active and important with respect to the electrodeposition of a PT film that possesses significant catalytic activity towards the oxidation of NADH. [ABSTRACT FROM AUTHOR]

Tyramine is an important neurotransmitter, neuromodulator, and neurohormone in insects. In honeybees, it is assumed to have functions in modulating sensory responsiveness and controlling motor behavior. Tyramine can bind to two characterized receptors in honeybees, both of which are coupled to intracellular cAMP pathways. How tyramine acts on neuronal, cellular and circuit levels is unclear. We investigated the spatial brain expression of the tyramine receptor AmTAR1 using a specific antibody. This antibody detects a membrane protein of the expected molecular weight in western blot analysis. In honeybee brains, it labels different structures which process sensory information. Labeling along the antennal nerve, in projections of the dorsal lobe and in the gnathal ganglion suggest that tyramine receptors are involved in modulating gustatory and tactile perception. Furthermore, the ellipsoid body of the central complex and giant synapses in the lateral complex show AmTAR1-like immunoreactivity (AmTAR1-IR), suggesting a role of this receptor in modulating sky-compass information and/or higher sensor-motor control. Additionally, intense signals derive from the mushroom bodies, higher-order integration centers for olfactory, visual, gustatory and tactile information. To investigate whether AmTAR1-expressing brain structures are in vicinity to tyramine releasing sites, a specific tyramine antibody was applied. Tyramine-like labeling was observed in AmTAR1-IR positive structures, although it was sometimes weak and we did not always find a direct match of ligand and receptor. Moreover, tyramine-like immunoreactivity was also found in brain regions without AmTAR1-IR (optic lobes, antennal lobes), indicating that other tyramine-specific receptors may be expressed there. [ABSTRACT FROM AUTHOR]

Polytyramine (PT) has been electro-deposited onto multi-walled carbon nanotube (MWCNT) modified glassy carbon (GC) electrodes via oxidation of tyramine in 0.1 M H3PO4 by cycling the potential over the range of −400 mV to 1300 mV ( versus Ag/AgCl). The reactivity of the resulting chemically-modified electrodes was characterized using cyclic voltammetry in the presence and absence of reduced nicotinamide adenine dinucleotide (NADH). The modified electrodes displayed electrochemical activity due to the formation of quinone species and were catalytically active towards NADH oxidation by lowering the oxidation peak potential by 170 mV compared to the value of the MWCNT modified electrode with a peak potential of 180±10 mV ( versus Ag/AgCl). The MWCNT/PT surface was further characterized using SEM and XPS methods, which indicated that a thin polymeric film had been formed on the electrode surface. The present work demonstrates the advantage of using PT as a platform that combines both the immobilization of alcohol dehydrogenase (ADH) and the mediation of NADH oxidation at a low overpotential essential to the design of high performance ethanol biosensors, all within an easily electropolymerizable film. The resulting biosensor displayed an ethanol sensitivity of 4.28±0.06 μA mM−1 cm−2, a linear range between 0.1 mM and 0.5 mM and a detection limit of 10 μM. [ABSTRACT FROM AUTHOR]

Steroid sulfatase ( STS) is responsible for the hydrolysis of biologically inactive sulfated steroids into their active un-sulfated forms and promotes the growth of various hormone-dependent cancers (e.g., breast cancer). Therefore, the STS enzyme is a promising therapeutic target for the treatment of steroid-sensitive cancers. Herein, we report the synthesis and biological evaluation of sulfamate analogs as potential STS inhibitors based on N-acylated tyramines that contain C-F bonds. The inhibitory effects of the analogs were tested using STS isolated from human placenta. Of the analogs tested, 4-(2-perfluoroundecanoylaminoethyl)-phenyl sulfamate, 5r, demonstrated the greatest inhibitory effect, with an IC50 value of 2.18 μ m ( IC50 value of 2.13 μ m for coumarin-7- O-sulfamate was used as a reference). These findings were supported by the results our computational analyses performed using molecular docking techniques. [ABSTRACT FROM AUTHOR]

New Findings What is the central question of this study? In young adults, about half of the cold-related reduction in skin blood flow during cold exposure is mediated by noradrenaline, while the remainder is attributable to other substances co-released with noradrenaline that have yet to be identified., What is the main finding and its importance? Purinergic receptor blockade blunted the vasoconstriction response to whole-body cooling and to intradermal administration of tyramine. These results indicate that ATP is necessary to vasoconstrict blood vessels in the skin adequately and prevent heat loss in a cold environment., Noradrenaline is responsible for eliciting ∼60% of the reflex cutaneous vasoconstriction (VC) response in young adults, while the remainder is attributable to one or more unidentified co-released sympathetic adrenergic neurotransmitter(s). Inconsistent evidence has placed neuropeptide Y in this role; however, other putative cotransmitters have yet to be tested. We hypothesize that ATP contributes to the reflex cutaneous VC response. Two protocols were conducted in young adults ( n = 10); both involved the placement of three microdialysis probes in forearm skin and whole-body cooling (skin temperature = 30.5°C). In protocol 1, the following solutions were infused: (i) lactated Ringer solution (control); (ii) 10 m m l-NAME; and (iii) purinergic receptor blockade with 1 m m suramin plus l-NAME. In protocol 2, the following solutions were infused: (i) lactated Ringer solution; (ii) suramin plus l-NAME; and (iii) suramin plus l-NAME plus adrenoreceptor blockade with 5 m m yohimbine plus 1 m m propranolol. Laser Doppler flux (LDF) was measured over each microdialysis site, and cutaneous vascular conductance (CVC) was calculated (CVC = LDF/MAP) and expressed as percentage changes from baseline (%ΔCVCBASELINE). l-NAME was used to block the vasodilatory influence of ATP and unmask the P2X-mediated VC response to exogenous ATP infusion (−21 ± 6%ΔCVCBASELINE). During cooling, the VC response (control, −39 ± 8%ΔCVCBASELINE) was attenuated at the suramin site (−21 ± 4%ΔCVCBASELINE) and further blunted with combined adrenoreceptor blockade (−9 ± 3%ΔCVCBASELINE; P < 0.05). Compared with the control site (−22 ± 5%ΔCVCBASELINE), suramin inhibited pharmacologically induced VC to tyramine (−12 ± 6%ΔCVCBASELINE; P < 0.05), which displaces adrenergic neurotransmitters from axon terminals. These data indicate that ATP contributes to the cutaneous VC response in humans. [ABSTRACT FROM AUTHOR]

Alcohol consumption is a widespread behaviour that may eventually result in the development of alcohol use disorder (AUD). Alcohol, however, is rarely consumed in pure form but in fruit- or corn-derived preparations, like beer. These preparations add other compounds to the consumption, which may critically modify alcohol intake and AUD risk. We investigated the effects of hordenine, a barley-derived beer compound on alcohol use-related behaviours. We found that the dopamine D2 receptor agonist hordenine (50 mg/kg) limited ongoing alcohol consumption and prophylactically diminished relapse drinking after withdrawal in mice. Although not having reinforcing effects on its own, hordenine blocked the establishment of alcohol-induced conditioned place preference (CPP). However, it independently enhanced alcohol CPP retrieval. Hordenine had a dose-dependent inhibitory effect on locomotor activity. Chronic hordenine exposure enhanced monoamine tissue levels in many brain regions. Further characterization revealed monoaminergic binding sites of hordenine and found a strong binding on the serotonin and dopamine transporters, and dopamine D 3 , and adrenergic α 1A and α 2A receptor activation but no effects on GABA A receptor or glycinergic signalling. These findings suggest that natural ingredients of beer, like hordenine, may work as an inhibitory and use-regulating factor by their modulation of monoaminergic signalling in the brain., (© 2023 The Authors. Addiction Biology published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.)

Novel polymeric cell adhesion inhibitors were developed in which the selectin tetrasaccharide sialyl-LewisX (SLeX) is multivalently presented on a biocompatible poly(2-hydroxypropyl)methacrylamide (PHPMA) backbone either alone (P1) or in combination with O-sulfated tyramine side chains (P2). For comparison, corresponding polymeric glycomimetics were prepared in which the crucial 'single carbohydrate' substructures fucose, galactose, and sialic acid side chains were randomly linked to the PHPMA backbone (P3 or P4 (O-sulfated tyramine)). All polymers have an identical degree of polymerization, as they are derived from the same precursor polymer. Binding assays to selectins, to activated endothelial cells, and to macrophages show that polyHPMA with SLeX is an excellent binder to E-, L-, and P-selectins. However, mimetic P4 can also achieve close to comparable binding affinities in in vitro measurements and surprisingly, it also significantly inhibits the migration of macrophages; this provides new perspectives for the therapy of severe inflammatory diseases. [ABSTRACT FROM AUTHOR]

Few information is available about the tyraminogenic potential of the species Enterococcus mundtii. In this study, two plant-derived strains of E. mundtii were selected and investigated to better understand the phenotypic behaviour and the genetic mechanisms involved in tyramine accumulation. Both the strains accumulated tyramine from the beginning of exponential phase of growth, independently on the addition of tyrosine to the medium. The strains accumulated also 2-phenylethylamine, although with lower efficiency and in greater extent when tyrosine was not added. Accordingly, the tyrosine decarboxylase ( tyr DC) gene expression level increased during the exponential phase with tyrosine added, while it remained constant and high without precursor. The genetic organization as well as sequence identity levels of tyr DC and tyrosine permease ( tyrP) genes indicated a correlation with those of phylogenetically closer enterococcal species, such as E. faecium, E. hirae and E. durans; however, the gene Na+/H+ antiporter ( nhaC) that usually follow tyrP is missing. In addition, BLAST analysis revealed the presence of additional genes encoding for decarboxylase and permease in the genome of several E. mundtii strains. It is speculated the occurrence of a duplication event and the acquisition of different specificity for these enzymes that deserves further investigations. [ABSTRACT FROM AUTHOR]

Background The role of diet in the management of the headache patient is a controversial topic in the headache field. Objectives To review the evidence supporting the hypothesis that specific foods or ingredients within foods and beverages trigger attacks of headache and/or migraine and to discuss the use of elimination diets in the prevention of headache disorders Methods This represents part 1 of a narrative review of the role of diet in the prevention of migraine and other headache disorders. A PubMed search was performed with the following search terms: 'monosodium glutamate,' 'caffeine,' 'aspartame,' 'sucralose,' 'histamine intolerance syndrome,' 'tyramine,' 'alcohol,' 'chocolate,' 'nitrites,' 'IgG elimination diets,' and 'gluten.' Each of these search terms was then cross-referenced with 'headache' and 'migraine' to identify relevant studies. Only studies that were written in English were included in this review. Results Caffeine withdrawal and administration of MSG (dissolved in liquid) has the strongest evidence for triggering attacks of headache as evidenced by multiple positive provocation studies. Aspartame has conflicting evidence with two positive and two negative provocation studies. Observational studies provide modest evidence that gluten- and histamine-containing foods as well as alcohol may precipitate headaches in subgroups of patients. Two of three randomized controlled trials reported that an elimination diet of IgG positive foods significantly decreased frequency of headache/migraine during the treatment as compared to baseline time period. Conclusions Certain foods, beverages, and ingredients within foods may trigger attacks of headache and/or migraine in susceptible individuals. Elimination diets can prevent headaches in subgroups of persons with headache disorders. [ABSTRACT FROM AUTHOR]

ABSTRACT Hydrogels generated by the interaction of two different water-soluble polymers offer access to a new group of soft materials. A prototype amino-functionalized polyphosphazene with both tyramine and ferulic acid-based side groups was coupled to aldehyde functionalized-dextrans to form hydrogels crosslinked via Schiff base chemistry. Synthesis of the polyphosphazene was accomplished by macromolecular substitution and protection-deprotection chemistry, with characterization by 1H NMR, 31P NMR, solid state 13C NMR, and DSC techniques. Combination of the aqueous polyphosphazene and aldehyde functionalized-dextran solutions at room temperature caused gelation with different gelation times and crosslink densities dependent on the aldehyde content of the dextran. The hydrogel properties were evaluated using rheology, thermal characterization, and cryo-microscopy. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2984-2991 [ABSTRACT FROM AUTHOR]

BACKGROUND: Ripened cheese is among fermented food the most often associated with food poisoning from biogenic amines. The influence of ripening time, heat treatment of milk and the effect of using milk from a different ewe breed on the biogenic amine (BA) content of Zamorano cheese was studied by high-performance liquid chromatography. Physicochemical, proteolytic andmicrobiological parameters were also studied. RESULTS: BA content increased significantly during ripening and their final values were around 400mg kg-1. Cheeses elaborated with raw milk duplicated the concentration of BA relative to those elaborated with pasteurized milk (72 °C for 20 s). The average levels of putrescine, spermine and tyramine were higher in cheeses made with a greater proportion of milk from Churra breed. Significant differences in microbial counts and nitrogen soluble in 5% phosphotungstic acid were observed between the different batches. CONCLUSION: Ripening time and heat treatment applied to milk were the factors that exercised the greatest influence upon the concentration of BA in Zamorano cheese. [ABSTRACT FROM AUTHOR]

We have studied gender differences in the direct and indirect sympathomimetic cardiovascular effects of the stimulant cathinone (from Khat) (and for comparison methylenedioxymethamphetamine [ MDMA]) and the archetypal indirect sympathomimetic agent tyramine, employing male and female Wistar rats., Animals were sympathectomized by treatment with 6-hydroxydopamine or treated with vehicle., In male and female vehicle-treated pentobarbitone-anaesthetized rats, all three agonists (0.001-1 mg/kg) produced significant tachycardia, tyramine produced large pressor, and in high doses small depressor responses, MDMA produced small pressor responses, and cathinone produced only minor pressor effects., In sympathectomized rats, pressor responses, even those to tyramine, were virtually abolished, and depressor responses to tyramine were abolished., In vehicle-treated rats, the tachycardia to tyramine, but not the tachycardia to cathinone or MDMA, was significantly greater in male than female rats. This may suggest that the mechanism of the tachycardia to tyramine differs from those of the stimulants cathinone and MDMA. Following sympathectomy, there were no differences between male and female rats in the tachycardia to any agent., Hence, there were gender differences in the tachycardia response for tyramine, but no gender differences in the cardiovascular responses to the widely used recreational stimulants cathinone and MDMA. Cardiac stimulant actions of cathinone and MDMA were similar in male and female rats. [ABSTRACT FROM AUTHOR]

Electrochemical polymerization of tyramine was achieved on copper electrode surface from tyramine in 0.3 M oxalic acid (pH = 1.2) solution by using cyclic voltammetry technique. The formation of polytyramine nanoparicles (PTN) were characterized by cyclic voltammetry (CV), fourier transform infrared- attenuated total reflectance (FTIR-ATR) spectroscopy and scanning electron microscopy (SEM). The corrosion behavior of PTN coated copper was investigated bymeans of the change of open circuit potential with exposure time (Eocpt), -electrochemical impedance spectroscopy (EIS) and anodic polarization curves in 3.5% NaCl solutions at room temperature. The obtained results showed the shift of corrosion potential toward positive values for electropolymerized copper and a significant decrease in corrosion current and corrosion rate in comparison with bare copper, so that the PTNs coating could be used as an important protection against corrosion of copper. [ABSTRACT FROM AUTHOR]

BACKGROUND Microbial transglutaminase ( MTGase) is an enzyme utilized in the food industry in many areas. In this study, the suppression effect of MTGase at various levels (0, 2, 5, 10 g kg−1) on the formation of biogenic amines in mackerel was determined during refrigerated storage of 8 days. RESULTS Mince added with 2 g kg−1 MTGase showed the lowest formation of putrescine, cadaverine and tyramine throughout the storage. Histamine exceeded the consumable limit (500 mg kg−1) after the 4th day, except for that containing 2 g kg−1 MTGase. The formation of total volatile basic nitrogen and total free amino acid content were retarded and the pH value was unaltered by addition of MTGase. With increasing MTGase levels, the growth of total psychrophilic bacteria, mould, yeast and coliform bacteria was retarded. The sensory scores of mackerel mince increased as MTGase concentrations increased. CONCLUSION MTGase plays a role in maintaining the quality of mackerel mince during refrigerated storage. As a result of the present study, a new use for MTGase in the food industry is revealed. It will contribute especially in the field of development of products for consumers with allergic sensitivity. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

ABSTRACT We have previously reported on a hydrogel system fabricated from poly(vinyl alcohol) (PVA) functionalized with tyramine groups (PVA-Tyr) that has the ability to co-polymerize with proteins in their native state. These gels were also shown to be hydrolytically degradable through the ester groups present in the functional groups. In this article, the hydrolytic degradation of the PVA-Tyr gels is shown to be strongly dependant on pH, where at pH < 7.4 the lack of ionization of the tyramine groups resulted in slower hydrolysis. The gels' degradation was also highly influenced by temperature, where heat (>25°C) was required to facilitate the hydrolysis of the ester bonds. Moreover, the degradation rates were successfully tailored between 19 to 27 days by varying the hydrogels' initial macromer concentration. It was highlighted that the cross-linking density was dependant on the sodium persulphate to tyramine ratio, as well as the viscosity of the macromer solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42142. [ABSTRACT FROM AUTHOR]

This study evaluated the presence of biogenic amines in fermented cow's and goat's milks containing probiotic bacteria, during the first 10 days of chilled storage (4 ± 2°C), when the probiotic strains are most viable. The overall acceptance of both fermented milks, produced using the same starter culture and probiotics, was tested. In both products, the initially high levels of tyramine (560 mg kg−1 means for both fermented milks), the predominant biogenic amine, increased during the storage period, which may be considered this amine as a quality index for fermented milks. The other principal biogenic amines (putrescine, cadaverine, histamine, and spermidine) were produced on days 1-5 of storage, and thereafter decreased. At the end of the 10th day, these amines, respectively, showed values of fermented cow's milk 20.26, 29.09, 17.97, and 82.07 mg kg−1; and values of fermented goat's milk 22.92, 29.09, 34.85, and 53.85 mg kg−1, in fermented cow's and goat's milk. Fermented cow's milk was well accepted compared to fermented goat's milk. The results suggested that the content of biogenic amines may be a criterion for selecting lactic acid bacteria used to produce fermented milks. [ABSTRACT FROM AUTHOR]

We synthesized and tested 3-chlorotyramine as a ligand of the D2 dopamine receptor. This compound displayed a similar affinity by this receptor to that previously reported for dopamine. In order to understand further the experimental results we performed a molecular modeling study of 3-chlorotyramine and structurally related compounds. By combining molecular dynamics simulations with semiempirical (PM6), ab initio and density functional theory calculations, a simple and generally applicable procedure to evaluate the binding energies of these ligands interacting with the D2 dopamine receptors is reported here. These results provided a clear picture of the binding interactions of these compounds from both structural and energetic view points. A reduced model for the binding pocket was used. This approach allowed us to perform more accurate quantum mechanical calculations as well as to obtain a detailed electronic analysis using the Quantum Theory of Atoms in Molecules (QTAIM) technique. Molecular aspects of the binding interactions between ligands and the D2 dopamine receptor are discussed in detail. A good correlation between the relative binding energies obtained from theoretical calculations and experimental IC50 values was obtained. These results allowed us to predict that 3-chlorotyramine possesses a significant affinity by the D2-DR. Our theoretical predictions were experimentally corroborated when we synthesized and tested 3-chlorotyramine which displayed a similar affinity by the D2-DR to that reported for DA. [ABSTRACT FROM AUTHOR]