Synthesis of phosphamide conjugates of 5"-mononucleotides with carcinine and its analogs

The reactions of histamine, the natural dipeptide carcinine (-Ala-HA), and its analogs with 5"-monodeoxyribonucleotides (dNMP) in the presence of triphenylphosphine, 2,2"-dipyridyl disulfide, and N-methylimidazole were studied. The yield of phosphamide derivatives decreases from 72% to 17% as the length of the linker group between the imidazole ring and the terminal aliphatic amino group is increased. Hydrolytic stability of the resulting conjugates was examined. The stability of the bonds in the —O—P(O)₂—NH— group linking the nucleotide and peptide portions of the conjugate depends on the nature of the heterocyclic base of the nucleotide and decreases in the series dTMP > dCMP > dAMP.     

A Dual-Mode Method Based on Aptamer Recognition and Time-Resolved Fluorescence Resonance Energy Transfer for Histamine Detection in Fish

Histamine produced via the secretion of histidine decarboxylase by the bacteria in fish muscles is a toxic biogenic amine and of significant concern in food hygiene, since a high intake can cause poisoning in humans. This study proposed a fluorometric and colorimetric dual-mode specific method for the detection of histamine in fish, based on the fluorescence labeling of a histamine specific aptamer via the quenching and optical properties of gold nanoparticles (AuNPs). Due to the fluorescence resonance energy transfer phenomenon caused by the proximity of AuNPs and NaYF4:Ce/Tb, resulting in the quenching of the fluorescence signal in the detection system, the presence of histamine will compete with AuNPs to capture the aptamer and release it from the AuNP surface, inducing fluorescence recovery. Meanwhile, the combined detection of the two modes showed good linearity with histamine concentration, the linear detection range of the dual-mode synthesis was 0.2–1.0 μmol/L, with a detection limit of 4.57 nmol/L. Thus, this method has good selectivity and was successfully applied to the detection of histamine in fish foodstuffs with the recoveries of 83.39~102.027% and 82.19~105.94% for Trichiurus haumela and Thamnaconus septentrionalis, respectively. In addition, this method was shown to be simple, rapid, and easy to conduct. Through the mutual verification and combined use of the two modes, a highly sensitive, rapid, and accurate dual-mode detection method for the analysis of histamine content in food was established, thereby providing a reference for the monitoring of food freshness.     

Structure-Activity Relationship of Hetarylpropylguanidines Aiming at the Development of Selective Histamine Receptor Ligands†

New classes of alkylated hetarylpropylguanidines with different functionality and variation in spacer length were synthesized to determine their behavior at the four histamine receptor (H₁R, H₂R, H₃R, H₄R) subtypes. Alkylated guanidines with different terminal functional groups and varied basicity, like amine, guanidine and urea were developed, based on the lead structure SK&F 91486 ( 2 ). Furthermore, heteroatomic exchange at the guanidine structure of 2 led to simple analogues of the lead compound. Radioassays at all histamine receptor subtypes were accomplished, as well as organ bath studies at the guinea pig (gp) ileum (gpH₁R) and right atrium (gpH₂R). Ligands with terminal functionalization led to, partially, highly affine and potent structures (two digit nanomolar), which showed up a bad selectivity profile within the histamine receptor family. While the benzoylurea derivative 144 demonstrated a preference towards the human (h) H₃R, S-methylisothiourea analogue 143 obtained high affinity at the hH₄R (pK_i=8.14) with moderate selectivity. The molecular basis of the latter finding was supported by computational studies.     

Reversible addition–fragmentation chain transfer synthesis of amidine‐based,CO2‐responsive homo and AB diblock (Co)polymers comprised of histamine and their gas‐triggered self‐assembly in water

Well‐defined homopolymers of pentafluorophenyl acrylate (PFPA) and AB diblock copolymers of N,N‐dimethylacrylamide (DMA) and poly(ethylene glycol) methyl ether acrylate (PEGA) with PFPA were prepared by reversible addition–fragmentation chain transfer (RAFT) radical polymerization. Three PFPA homopolymers of different molecular weights were reacted with the commercially available amidine and guanidine species histamine (HIS) dihydrochloride and L ‐arginine methyl ester (ARG) dihydrochloride in the presence of S‐methyl methanethiosulfonate to yield, quantitatively, the corresponding amidine and guanidine‐based acrylamido homopolymers. Both the HIS and ARG homopolymers are known to reversibly bind CO₂ with, in the case of the former, CO₂ fixation being accompanied with a switch from a hydrophobic to hydrophilic state. The RAFT synthesis of PFPA‐DMA and PEGA‐PFPA diblock copolymers yielded well‐defined materials with a range of molar compositions. These precursor materials were converted to the corresponding HIS and ARG block copolymers whose structure was confirmed using ¹H NMR spectroscopy. Employing a combination of dynamic light scattering and transmission electron microscopy, we demonstrate that the DMA‐HIS and PEGA‐HIS diblock copolymers are able to undergo reversible and cyclable self‐directed assembly in aqueous media using CO₂ and N₂ as the triggers between fully hydrophilic and amphiphilic (assembled) states. For example, in the case of the 54:46 DMA‐HIS diblock, aggregates with hydrodynamic diameters of about 40.0 nm are readily formed from the molecularly dissolved state. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Gas Chromatographic Determination of Microgram and Nanogram Quantities of Histamine as Its Na-Trifluoroacetyl-Nim-Carbethoxy Derivative

Abstract

A method has been devised for the quantitative estimation of microgram and nanogram quantities of histamine as its N^a-trifluoroacetyl-N^im-carbethoxy derivative. Trifluoroacetic anhydride was used for the formation of N^a-trifluoroacetyl derivative and ethoxyformic anhydride was used for the N^im-carbethoxy derivative. Quantitative determinations were made in the range of 20 to 100 micrograms and 250 and 1000 nanograms with a mean standard deviation of 2–3%. The standard curves were linear.     

Equilibria and kinetics for p H-dependent axial ligation of alkyl(aquo) cobaloximes with aromatic and aliphatic N-donor ligands

Equilibria and kinetics of the reaction of bromomethyl(aquo) cobaloxime with histamine, histidine, glycine and ethyl glycine ester and iodomethyl(aquo) cobaloxime with cyanide, imidazole and substituted imidazoles were studied as a function ofpH at 25°C, 10 M ionic strength (KCl) by spectrophotometry technique. The rate of substitution of H₂O varies with thepKa of the incoming ligand, thus establishing the existence of nucleophilic participation of the ligand in the transition state. Dissociation kinetic reactions were also studied as a function ofpH. Binding and kinetic data were interpreted based on the basicity, steric crowd of the entering ligand and HSAB principle. To compare the rate constants of the entering ligandspH independent second-order rate constants were calculated.     

Simultaneous determination of 10 first-generation histamine h1 receptor blockers in feeds by ultra-high-performance liquid chromatography triple quadrupole ion trap hybrid mass spectrometer

A method for simultaneous determination of 10 first-generation histamine H1 receptor blockers in feeds by ultra-high-performance liquid chromatography triple quadrupole mass spectrometry combined with solid phase extraction. Instrument conditions, extraction solvents, and purification methods have been optimized. Under the optimum conditions, these analytes were separated effectively at 6 min. These feeds have been extracted by acid acetonitrile and purified by mixed cation exchange solid-phase extraction. The performance of this method meets the requirements of veterinary residue detection in feeds in China. It is appropriate for the confirmatory monitoring and quantitative analysis of 105 feed samples, five kinds of histamine H1 receptor blockers have been detected in 10 samples.     

邻苯二甲醛衍生高效液相色谱法快速测定血小板中组胺含量

An HPLC method for the determination of histamine(HA)in platelet.based on pre-column derivatiza-tion with o-phthalaldehvde(OPA ).is described.The HA was allowed to react with OPA at -10℃ for30min.HPLC was performed on a reversed-phase column with isocratic elution using sodium acetate buffer inmethanol as eluent system.A fluorescence detection system was used;excitation was set at 350.0nm andemission was read at 445.5nm,A good linear relationship was found in the range of 3.75×10￣(-3)～10. 5nmol.