Isolation and identification of tyramine-producing bacteria and their biogenic amines formation during fermentation of sufu.

The Chinese traditional soybean product, sufu, is getting increasingly popular in Asia for its special taste and rich nutrition. In this paper, physicochemical properties of sufu during fermentation, isolation and characterization of BA-producing bacteria, as well as their decarboxylase activities were thoroughly investigated. Tyramine, putrescine, phenylethylamine and cadaverine were the main BA in sufu fermentation. Tyramine level increased drastically to reach 513.72 mg/kg during sufu ripening, posing potential health risks. During sufu fermentation, there was a positive correlation between amino nitrogen and BA, yet no significant correlation was found between BAs with pH and total acidity. Additionally, 23 strains of tyramine- and phenylethylamine-producing bacteria harboring the TDC gene, including Enterococcus faecalis 45, Enterococcus faecium 36, Pediococcus acidilactici 310 and Pediococcus pentosaceus 27 that were responsible for tyramine production in sufu have been characterized. The current study provides insights into understanding the production of tyramine in sufu by microorganisms, which laid the groundwork for controlling biogenic amine production in fermented soybean products.

New Tyramine- and Aporphine-Type Alkamides with NO Release Inhibitory Activities from Piper puberulum.

Three new tyramine-type alkamides (1-3), three new natural products (4-6), five new N-acylated/formylated aporphine alkamides with different ratios of rotational isomers (7-11), and 20 known alkamides (12-31) were isolated from an EtOH extract of the stems and leaves of Piper puberulum. The absolute configurations of compounds 7, 8, and 10 were determined by single-crystal X-ray diffraction analysis. In the biological activity assay, compounds 3, 5, and 10-23 displayed inhibitory effects against lipopolysaccharide-induced NO release in BV-2 microglial cells, exhibiting IC50 values of 0.93-45 µM.

Theoretical and experimental proof for selective response of imprinted sorbent - analysis of hordenine in human urine.

The objective of this paper was to extend comprehensive theoretical and experimental investigations at the molecular level to identify factors responsible for the high selectivity of imprinted sorbents. This knowledge was utilized in a new analytical strategy devoted to the analysis of hordenine in human urine after beer consumption. Among the various polymeric compositions tested, the most effective material was built up from methacrylic acid and ethylene glycol dimethacrylate (MIP1), showing a satisfactory binding capacity (4.44 ±â€¯0.15 µmol g-1) and high specificity towards hordenine (AF = 5.90). The comprehensive analyses of porosity data and surface measurements revealed differences between imprinted polymers. The characterization of binding sites of MIP1 revealed a heterogeneous population with two values of Kd (2.75 and 370 µmol L-1) and two values of Bmax (1.82 and 99 µmol g-1) for higher and lower affinity respectively. The extensive theoretical analyses of interactions between various analytes and the MIP model cavity showed the highest binding energy for hordenine (ΔEB1 = -175.17 kcal mol-1). The method was validated for selectivity, lowest limit of quantification, calibration curve performance, precision, accuracy, matrix effect, carry-over and stability in urine. Extracts were prepared according to guidelines of the European Medicines Agency. The validation criteria were fulfilled, and the method was satisfactorily applied to urine samples collected prior to, and 2 h after, consumption of 2 L of beer, revealing the presence of hordenine at the mean level of 129 ±â€¯27 ng mL-1. Additionally, ability of the sorbent to purify the urine sample was assessed using flow injection analysis tandem mass spectrometry, for comparison with other extraction techniques.

A Quorum-Sensing Inhibitor Strain of Vibrio alginolyticus Blocks Qs-Controlled Phenotypes in Chromobacterium violaceum and Pseudomonas aeruginosa.

The cell density-dependent mechanism, quorum sensing (QS), regulates the expression of virulence factors. Its inhibition has been proposed as a promising new strategy to prevent bacterial pathogenicity. In this study, 827 strains from the microbiota of sea anemones and holothurians were screened for their ability to produce quorum-sensing inhibitor (QSI) compounds. The strain M3-10, identified as Vibrio alginolyticus by 16S rRNA gene sequencing, as well as ANIb and dDDH analyses, was selected for its high QSI activity. Bioassay-guided fractionation of the cell pellet extract from a fermentation broth of strain M3-10, followed by LC-MS and NMR analyses, revealed tyramine and N-acetyltyramine as the active compounds. The QS inhibitory activity of these molecules, which was confirmed using pure commercially available standards, was found to significantly inhibit Chromobacterium violaceum ATCC 12472 violacein production and virulence factors, such as pyoverdine production, as well as swarming and twitching motilities, produced by Pseudomonas aeruginosa PAO1. This constitutes the first study to screen QSI-producing strains in the microbiota of anemones and holothurians and provides an insight into the use of naturally produced QSI as a possible strategy to combat bacterial infections.

Perylene Bisimide Aggregates as Probes for Subnanomolar Discrimination of Aromatic Biogenic Amines.

Perylene bisimide derivatives show peculiar physical chemical features, such as a highly conjugated system, high extinction coefficients and elevated fluorescence quantum yields, making them suitable for the development of optical sensors of compounds of interest. In particular, they are characterized by the tendency to aggregate into π-π stacked supramolecular structures. In this contribution, the behavior of the PBI derivative N, N'-bis(2-(trimethylammonium)ethylene)perylene bisimide dichloride was investigated both in aqueous solution and on solid support. The electronic communication between PBI aggregates and biogenic amines was exploited in order to discriminate aromatic amines down to subnanomolar concentrations by observing PBI fluorescence variations in the presence of various amines and at different concentrations. The experimental findings were corroborated by density functional theory calculations. In particular, phenylethylamine and tyramine were demonstrated to be selectively detected down to 10-10 M concentration. Then, in order to develop a surface plasmon resonance (SPR) device, PBI was deposited onto a SPR support by means of the layer-by-layer method. PBI was deposited in the aggregated form and was demonstrated to preserve the capability to discriminate, selectively and with an outstanding analytical sensitivity, tyramine in the vapor phase and even if mixed with other aromatic amines.

A amperometric immunosensor for sensitive detection of circulating tumor cells using a tyramide signal amplification-based signal enhancement system.

Herein, tyramide signal amplification (TSA)-based electrochemical immunosensor was exploited for highly sensitive detection of CTCs. In this immunosensor, the nucleolin-targeting aptamer AS1411 (CP) was used to specifically capture tumor cells, and a TSA-based signal enhancement system consisting of Pt NPs@HRP@CP composite as catalytic probe and tyramine functionalized infinite coordination polymer (ICPs@Tyr) as electroactive signal tag was applied to improve the detection sensitivity. Using HeLa cell as the model CTCs, after a sandwich reaction, CP-HeLa-Pt NPs@HRP@CP bioconjugates were formed on the electrode. Millions of ICPs@Tyr could be layer-by-layer deposited onto the target cell membrane by the catalysis of Pt NPs@HRP@CP. The developed immunorsensor could detect HeLa cell with a wide dynamic range from 2 to 2 × 104 cells/mL and a detection limit of 2 cells/mL. Most importantly, the amperometric immunosensor was successfully applied to discriminate tumor cells from white blood cells, exhibiting high specificity and sensitivity. In conclusion, this work demonstrates that the TSA-based signal enhancement system might be a potential alternative tool for the electrochemical measurement of trace amounts of CTCs in clinical diagnosis.

A dual-function molecularly imprinted optopolymer based on quantum dots-grafted covalent-organic frameworks for the sensitive detection of tyramine in fermented meat products.

Molecular imprinting is a technique for polymerization using a template molecule to produce cavities in the polymer with high selectivity. The successful synthesis of a dual-function molecularly-imprinted optopolymer (MIOP) based on quantum dots-grafted covalent-organic frameworks as adsorbents has allowed the simultaneous detection of tyramine by optosensing and solid-phase extraction coupled with high performance liquid chromatography (SPE-HPLC). The MIOP, obtained by a one-pot reverse microemulsion polymerization, selectively measured tyramine from fermented meat products. Under optimized conditions, the relative fluorescence intensity of the optosensing method increased linearly at tyramine concentrations from 35 to 35,000 µg/kg, with a detection limit of 7.0 µg/kg. For SPE-HPLC, the linear range was from 20 to 2000 µg/kg, with a detection limit of 5 µg/kg. The optosensing based on MIOP is a rapid and selective method that would be suitable for detecting TYM in food, while SPE-HPLC also provided good levels of accuracy, sensitivity, and selectivity.

Isolation and identification of two alkaloid structures with radical scavenging activity from Actinokineospora sp. UTMC 968, a new promising source of alkaloid compounds.

For decades, natural products from Actinomycetes have been recognized as one of the inestimable sources of therapeutic compounds. Presently, due to some challenges in the identification of novel compounds including the validation of novel natural products and their compatibility with the high throughput screening bioassays, evaluating new activity from known commercial ones would be an important designation. On the other hand, finding new sources of bioactive compounds from Actinomycetes can be promising in attaining pharmaceutical compounds with fewer purification steps and cost-effective production of the bioproducts. Here we describe the isolation and identification of two alkaloid compounds from a soil actinobacterium Actinokineospora sp. UTMC 968 including N-acetyltyramine (1) and N-acetyltryptamine (2) with revealing a new bioactivity for these molecules. The producer is a rare actinobacterium belonging to family Pseudonocardiaceae as the first alkaloid compounds producer genus in its family. The structures of alkaloid 1 and 2 were assigned on the basis of 1D and 2D NMR spectroscopy and MS analyses. Compound 1 and 2 are used commercially for their pharmaceutical activity but their radical scavenging activity has not previously been reported. The results of 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay represented a remarkable DPPH radical scavenging capability with an IC50 value of 64.7 ± 0.5 and 131.3 ± 1.8 µg/mL for compound 1 and 2, respectively.

Competitive fluorescent pseudo-immunoassay exploiting molecularly imprinted polymers for the detection of biogenic amines in fish matrix.

We developed a competitive fluorescent molecularly imprinted polymer (MIP) assay to detect biogenic amines in fish samples. MIPs synthesized by precipitation polymerization using histamine as template were used in a batch binding assay analogous to competitive fluoroimmunoassays. Introducing a complex sample matrix, such as fish extract, into the assay changes the environment and the binding conditions, therefore the importance of the sample preparation is extensively discussed. Several extraction and purification methods for fish were comprehensively studied, and an optimal clean-up procedure for fish samples using liquid-liquid extraction was developed. The feasibility of the competitive MIP assay was shown in the purified fish extract over a broad histamine range (1 - 430µM). The MIP had the highest affinity towards histamine, but recognized also the structurally similar biogenic amines tyramine and tryptamine, as well as spermine and spermidine, providing simultaneous analysis and assessment of the total amount of biogenic amines.

Isolation and identification of allergens and biogenic amines of Prosopis juliflora genotypes

Background: Prosopis, or mesquite (Prosopis juliflora (Sw.) DC.), was introduced in Saudi Arabia several decades ago and is heavily used in street, roadside, and park plantations. It shows great adaptation to the prevailing climatic conditions such as high temperature, severe drought, and salinity and spreads naturally in many parts of the Kingdom. This research was conducted to isolate allergen proteins and biogenic amines from the pollen grains of P. juliflora genotypes in Saudi Arabia from two regions, namely Al-Qassim and Eastern regions. Results: The results showed that 18 different allergen proteins were detected in P. juliflora genotypes, with molecular weight ranging from 14 to 97 kDa. Moreover, P. juliflora genotypes from the two studied regions contained eight biogenic amines, namely histamine, tyramine, tryptamine, ß-phenylethylamine, butricine, codapherine, spermidine, and spermine. All genotypes from the Al-Qassim region were found to contain all eight amines, while in the Eastern region, histamine was absent in three genotypes, spermine was absent in six genotypes, and spermidine was absent in three genotypes. Genotypes B23, E20, and E21 had the lowest biogenic amine quantity. Conclusions: All identified proteins from mesquite trees from both regions (Eastern and Al-Qassim) cause allergies in patients who are sensitive to pollen grains. Bioamines, except histamine and tyramine, were recorded at varying concentrations in different genotypes.

Determination of Nonvolatile Amines in Foods by Improved Dansyl Derivatization Reaction.

An analytical method for the determination of nonvolatile amines (putrescine, cadaverine, histamine, tyramine, and spermidine) in foods was developed, using an improved dansyl derivatization technique. The five amines were extracted from food with 1% trichloroacetic acid. Three milliliter of extract was applied to a polymer-based strong cation exchange resin mini-column, which was washed with 5 mL of water, and eluted with 5 mL of 1 mol/L potassium carbonate solution. The eluate was dansylated, then 5 mL of toluene was added with shaking. The toluene layer was evaporated. The residue was taken up in 1 mL of acetonitrile and shaken with 1 mL of 5% proline in 1 mol/L potassium carbonate solution. The upper acetonitrile layer was collected, filtered, and subjected to HPLC. The limits of quantitation for putrescine and cadaverine in the samples were both 0.2 µg/g; those of spermidine, tyramine, and histamine were 0.8, 2.0, and 5.0 µg/g, respectively. The average recoveries of the five amines from nine foods exceeded 80%.

Benzoyltyramine Alkaloids Atalantums A-G from the Peels of Atalantia monophylla and Their Cytotoxicity against Cholangiocarcinoma Cell Lines.

Seven new benzoyltyramines, atalantums A-G (1-7), and five known compounds were isolated from the peels of Atalantia monophylla. All compounds were examined for cytotoxicity against the cholangiocarcinoma cell lines KKU-M214, KKU-M213, and KKU-M156. Compound 5 exhibited the strongest cytotoxicity against KKU-M156 cells, with an IC50 value of 1.97 ± 0.73 µM, an approximately 4.7-fold higher activity than that of the ellipticine standard. Compound 1 displayed strong cytotoxicity against KKU-M214 cells, with an IC50 value of 3.06 ± 0.51 µM, nearly equal to that of the 5-fluorouracil standard. In the case of the KKU-M213 cell line, compounds 2, 4, and 11 exhibited stronger cytotoxicity than the ellipticine standard, with IC50 values of 2.36 ± 0.20, 5.63 ± 0.22, and 2.71 ± 0.23 µM, respectively. Compounds 1, 5, and 7 displayed cytotoxicity against KKU-M214 cells, with IC50 values of 3.06 ± 0.51, 8.44 ± 0.47, and 7.37 ± 1.29 µM, respectively.

Tyramine and ß-phenylethylamine, from fermented food products, as agonists for the human trace amine-associated receptor 1 (hTAAR1) in the stomach.

The aromatic amines tyramine and ß-phenylethylamine are abundant in fermented foods. Recently, a family of human trace amine-associated receptors (hTAARs) was discovered that responds to these compounds. This study examined the expression of hTAAR genes in five human organs. Among them, the stomach expressed hTAAR1 and hTAAR9. Interestingly, more hTAAR1 was expressed in the pylorus than in the other stomach regions. The CRE-SEAP reporter assay revealed that only hTAAR1 functioned as a Gs-coupled receptor in response to tyramine and ß-phenylethylamine stimulation. The ß-phenylethylamine-mediated hTAAR1 activity could be potentiated using 3-isobutyl-1-methylxanthine. These data suggest that tyramine and ß-phenylethylamine in fermented foods act at hTAAR1 as agonists in the pylorus of stomach.

New aristolochic acid and other chemical constituents of Aristolochia maurorum growing wild in Jordan.

Investigation of the chemical constituents of Aristolochia maurorum growing wild in Jordan resulted in the isolation and characterisation of one new compound in addition to 19 known compounds. The new compound was identified as aristolochic acid II alanine amide (14). The other known compounds were the following: palmitic acid (1), ß-sitosterol (2), E-ethyl-p-coumarate (3), Z-ethyl-p-coumarate (4), aristolochic acid IV methyl ester (5), aristolactam I (6), loliolide (7), (+)-dehydrovomifoliol (8), glycerol-1-palmitate (9), aristolochic acid I (10), E-p-coumaric acid (11), E-N-coumaroyltyramine (12), ß-sitosteryl glucoside (13), aristolochic acid IV (15), aristolochic acid III (16), esculetin (17), uracil (18), shepherdine (19) and adenosine (20). The isolated compounds were characterised by different spectroscopic methods including NMR (1D and 2D), UV, IR and HRESIMS.

Three new acyltyramines from Anisodus luridus Link et Otto (Solanaceae).

Three new acyltyramines, N-[2-(4-hydroxyphenyl)ethyl]hentriacontanamide (1), N-[2-(4-hydroxyphenyl)ethyl]nonacosanamide (2) and N-[2-(4-hydroxyphenyl)ethyl]heneicosanamide (3) have been isolated from n-hexane extract of leaves of Anisodus luridus (Solanaceae). Successive extraction of defatted leaves of A. luridus with methanol afforded a residue on removal of solvent under reduced pressure. Residue was partitioned by means of chloroform and n-butanol. Chromatographic resolution of n-BuOH extract afforded six known compounds, apigenin (4), luteolin (5), quercetin (6), quercetin 3-O-α-l-rhamnoside (7), kaempferol 3-O-α-rhamnoside (8) and quercetin 3-O-α-l-rhamnopyranosyl-(1→6)-ß-d-glucopyranoside (9). The structures of the isolated compounds were assigned with the help of spectroscopic techniques. This is the first report of isolation of these compounds from this plant.

Screening of bromotyramine analogues as antifouling compounds against marine bacteria.

Rapid and efficient synthesis of 23 analogues inspired by bromotyramine derivatives, marine natural products, by means of CuSO4-catalysed [3+2] alkyne-azide cycloaddition is described. The final target was then assayed for anti-biofilm activity against three Gram-negative marine bacteria, Pseudoalteromonas ulvae (TC14), Pseudoalteromonas lipolytica (TC8) and Paracoccus sp. (4M6). Most of the synthesised bromotyramine/triazole derivatives are more active than the parent natural products Moloka'iamine (A) and 3,5-dibromo-4-methoxy-ß-phenethylamine (B) against biofilm formation by the three bacterial strains. Some of these compounds were shown to act as non-toxic inhibitors of biofilm development with EC50 < 200 µM without any effect on bacterial growth even at high concentrations (200 µM).

An Easily Fabricated Electrochemical Sensor Based on a Graphene-Modified Glassy Carbon Electrode for Determination of Octopamine and Tyramine.

A simple electrochemical sensor has been developed for highly sensitive detection of octopamine and tyramine by electrodepositing reduced graphene oxide (ERGO) nanosheets onto the surface of a glassy carbon electrode (GCE). The electrocatalytic oxidation of octopamine and tyramine is individually investigated at the surface of the ERGO modified glassy carbon electrode (ERGO/GCE) by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several essential factors including the deposition cycle of reduced graphene oxide nanosheets and the pH of the running buffer were investigated in order to determine the optimum conditions. Furthermore, the sensor was applied to the quantification of octopamine and tyramine by DPV in the concentration ranges from 0.5 to 40 µM and 0.1 to 25 µM, respectively. In addition, the limits of detection of octopamine and tyramine were calculated to be 0.1 µM and 0.03 µM (S/N = 3), respectively. The sensor showed good reproducibility, selectivity and stability. Finally, the sensor successfully detected octopamine and tyramine in commercially available beer with satisfactory recovery ranges which were 98.5%-104.7% and 102.2%-103.1%, respectively. These results indicate the ERGO/GCE based sensor is suitable for the detection of octopamine and tyramine.

One Step to Separate Five Alkaloids from Hypecoum leptocarpum by High-Speed Counter-Current Chromatography.

High-speed counter-current chromatography (CCC) was firstly and successfully applied for the preparative separation and purification of alkaloids from crude extract of Hypecoum leptocarpum. After the measurement of partition coefficient of five target alkaloids in the two-phase solvent systems, the CCC was performed well with a two-phase solvent system composed of tetrachloromethane-chloroform-methanol-0.1 M HCl at a volume ratio of 1.5 : 2.5 : 3 : 2 (V/V/V/V). The upper phase was used as the stationary phase, and the lower phase was used as the mobile phase. From 120 mg crude extract, 5 mg leptopidine, 32 mg oxohydrastinine, 27 mg (-)-N-methylanadine, 7 mg N-feruloyltyramine and 3 mg hypecoleptopine could be successfully separated. The amides alkaloid, N-feruloyltyramine, was firstly separated from H. leptocarpum. High-performance liquid chromatography analysis showed that the purity of each of the five target alkaloids was over 92%. Their chemical structures were confirmed by (1)H-NMR and (13)C-NMR data.

NMR-based identification of the phenolic profile of fruits of Lycium barbarum (goji berries). Isolation and structural determination of a novel N-feruloyl tyramine dimer as the most abundant antioxidant polyphenol of goji berries.

Biological properties of fruits of Lycium barbarum (goji berries) have been ascribed to their high content of nutrients and phenolics. Comprehensive studies aimed at unambiguously identifying the phenolic components in goji berries are still lacking. In this paper, we report on the isolation and NMR-based identification of the major phenolics in commercially available goji berries. Together with already known phenolics, including caffeic acid, p-coumaric acid, rutin, scopoletin, N-trans-feruloyl tyramine, and N-cis-feruloyl tyramine, an unreported N-feruloyl tyramine dimer was characterized as the most abundant polyphenol isolated from the berries. Usually divalent molecules show enhanced biological activities than their corresponding monomers.