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Isolation and structure elucidation of the title compounds (I), which show inhibitory activity against acetylcholinesterase, are described.

Photoinduced electron transfer (ET) is studied in a series of novel molecules containing a dimethoxynaphthalene (DMN) donor and either a pyridine (P) or N-methylpyridinium (P-Me + ) acceptor covalently linked via a rigid nonbornalogous bridge ( n sigma bonds in length). ET rates of the order of 10 10 s −1 were measured for the DMN- n -P-Me + series ( n = 4, 6), while no appreciable ET was observed for the DMN- n -P compounds. Electronic and nuclear factors are discussed and the results rationalized in terms of Marcus—Hush and non-adiabatic ET theories.

The photoreactions of 3-methoxycarbonyl-N-methylpyridinium perchlorate (1a) and 3-carbamoyl-N-methylpyridinium perchlorate (1b) under N2 give the products methylated at the 6- and 4-positions in methanol. Under O2, the photoreaction of 1a is drastically changed to give a product methoxylated at the 2-position and hydroxylated at the 5-position simultaneously. This compound is unstable and changes to 5-hydroxy-3-methoxycarbonyl-N-methyl-2-pyridone (5a). Only one atom of O2 is incorporated in 5a. The photoreaction of 1b is completely inhibited by O2.

A column containing N-methylpyridinium polymer was used in the chromatographic investigation of complex of human serum albumin and sodium aurothiomalate. The serum albumin-sodium aurothiomalate complex was separated from the components of serum albumin. The peak height of the complex increased with increasing the incubation time of albumin and sodium aurothiomalate, with a concomitant decrease of mercaptalbumin peak height. The nature of the mercaptalbumin participation in this complex formation was elucidated. The formation of the complex was observed in vitro, but not in the serum of a patient with rheumatoid arthritis receiving sodium aurothiomalate therapy.

Semiempirical (MNDO, AM1 and PM3) as well as ab initio (MP2/6-31G * //6-31G * ) calculations indicate that γ-methylenepyrans are more stable than their α-methylenepyran isomers (pyrylium anhydrobases). This provides an explanation for the higher rate of hydrogen isotope exchange of γ- over α-methyl substituted pyrylium salts in protic media, since transition states related in energy to these methylenepyran intermediates evidently are involved. Conversely, for substituted N-methylpyridinium salts, the calculations indicate the opposite α- vs γ-stability order and support a similar explanation for the lower rate of hydrogen isotopic exchange at the γ- than at the α-methyl groups.

Human serum albumin (HSA) labeled with 99mTc (99mTc-HSA) was analyzed by high performance liquid chromatography using a 4-vinylpyridinium polymer column which specifically resolved albumin components such as human mercaptalbumin (HMA), human non-mercaptalbumins (HNA), etc. The 99mTc-HSA radiochromatogram revealed that 99mTc-HSA consisted of several components. The radiochromatographic profile was similar to that of 99mTc-HMA prepared with 99mTc and separated HMA. This suggested that HMA participated mainly in 99mTc-labeling of HSA. When HSA was labeled with a stoichiometric concentration of 99Tc, the HMA peak was significantly decreased and new peaks were revealed by absorbance at 280 nm. From these results, the role of HMA in labeling HSA with 99mTc was elucidated.

Isomeric bis-terpyridine complexes of iridium(III) incorporating meta- or para-N-methylpyridyl substituents at the terpyridine 4′-position display long-lived luminescence in solution which is quenched by chloride ions to very different extents.

The vibrational spectra of N -methylpyridinium iodide and three of its selectively deuterated derivatives have been recorded in the crystalline as w

A new N-methylpyridinium alkaloid, with an interesting antiproliferative activity in vitro, has been isolated from the Mediterranean tunicate Microcosmus vulgaris. Its structure has been elucidated by spectroscopic analysis, including extensive 2D NMR experiments.

Two antimicrobial fractions were obtained from the sponge Calyx podatypa from the Bahamas. The less polar fraction contained the known compounds xestamines A [1] and B [2] and three new metabolites called xestamines D [3], E [4], and F [5]. The more polar fraction consisted of a mixture of xestamines G [6] and H [7].

Dithienylethenes having a pyridinium cation at one and both thiophene rings were synthesized. The derivatives with two pyridinium cation showed the cyclization quantum yield as high as 0.71, which is much larger than the values of the monocation derivative and the neutral form. This can be explained by the conformation of the open-ring isomer of the diarylethenes.

Three new N-methyl pyridinium alkaloids, platisidines A-C (1-3), were isolated from an Okinawan marine sponge of the genus Plakortis, and the structures were elucidated from spectroscopic data. The structures of platisidines A-C (1-3) were elucidated to be N-methyl nicotinic acid derivatives with a n-hexadecanoyl chain. Platisidines A-C (1-3) showed inhibitory activity against acetylcholinesterase.

La reaction du nitromethane avec des chlorures de pyridinium dans l'ammoniac liquide conduit a des [nitromethylene-4 dihydro-1,4] pyridines

La reaction du nitromethane avec des chlorures de pyridinium dans l'ammoniac liquide conduit a des [nitromethylene-4 dihydro-1,4] pyridines

The effect of N-methylpyridinium-2-aldoxime methane sulphonate (P2S), a drug recommended for prophylactic and therapeutic purposes in organophosphate poisoning, on intestinal (Na-K) ATPase and adenyl cyclase activities, was tested in rats. Intestinal (Na-K) ATPase activity was determined 5 h after intragastric administration of either 0.15 M NaCl or P2S 200 mg/kg body weight. P2S decreased significantly jejunal and colonic (Na-K)ATPase activity, 17.1 +/- 4.8 (S.E.) and 13.5 +/- 3.0, as compared to that in saline-treated rats, 41.5 +/- 3.0 (S.E.) and 25.4 +/- 1.2 mumol Pi/mg protein per h, respectively. Pretreatment with methyl prednisolone did not prevent the decrease in enzyme activity induced by P2S. Mucosal PGE2 and cAMP contents, adenyl cyclase and phosphodiesterase activities, were similar in P2S and saline-treated rats. It is thus suggested that P2S-induced inhibition of intestinal (Na-K)ATPase activity might be among the mechanisms contributing to looseness of the stool frequently observed following P2S administration.

The electrochemical reduction of N-methylpyridinium ion (NMP+) at concentrations

Reaction of insulin with 2-chloro- or 2-iodo-N-methylpyridinium iodide affords, amongst others, an insulin analogue modified at tha A14-tyrosine residue. Degradative procedures which pinpoint the exact position of modification are described. Highest yields of the derivative are obtained using the 2-iodo-N-methylpyridinium iodide as reagent. In the mouse convulsion assay this derivative retains 72% of its activity.

Reaction of 2-iodo-N-methylpyridinium iodide with insulin gave, amongst others, A19- and B16-(N-methylpyridinium)insulin derivatives in which the phenolic groups of the respective tyrosines had been modified. Under carefully controlled conditions the A19 derivative gave small rhombohedral crystals, whereas the B16 derivative failed to crystallize. Both these derivatives had low biological activities.

Reduction de Fe(III) TMPyP et oxydation de Fe(II) TMPyP par O 2 et H 2 O 2 . Reactions redox. Mecanisme de reaction.TMPyP: la porphyrine(tetrakis-[methyl-«1» pyridinio-«4»]-«5,10,15,20»)

— The synthesis of 4-(N-methylpyridinium) t-butyl nitrone (4-MePyBN) and its use as a spin trap for superoxide radicals produced in aqueous solutions is reported (aN= 13.78 G, aHs= 1.65 G, and g = 2.0091). The half-life of the spin adduct as a function of pH (83 s at pH 5.5, 78 s at pH 7.0, and 65 s at pH 8.0) the effects of iron salts, diethylenetriaminepentacetic acid (DETAPAC), and superoxide dismutase were examined, and comparisons made between 4-MePyBN and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin trapping agents for the superoxide radical.

N-Methylpyridinium-diiodocuprate(I), C6H8NCuI2 and dimethyl(3-dimethylamino-2-aza-2-propenyliden)ammonium-diiodocuprate(I), C6H14N3CuI2, are obtained by reacting Cu with C6H8NI3 or C6H14N3I3 in acetone. Both compounds are built up by the organic cations and chains of edge sharing tetrahedra1 ∞[Cul4/2-]. The iodocuprate(I) anions are in intimate contact with the cations via intermolecular I···C interactions. Though nearly the same average Cu-I distance of 267.2 or 268.2 pm was found for both iodocuprate(I) anions there are different Cu-Cu distances (301-354 pm).

The passage of 2-hydroxyiminomethyl- N -methylpyridinium methanesulfonate (P2S) to the perfused cerebral spaces of pregnant does and to their fetuses has been studied. The oxime did not penetrate into the fetus after intravenous injection of 30 mg/kg though it did after 60 mg/kg or continuous slow infusion of 2.5 mg/kg/min during 45 minutes. In all cases P2S was found in the perfusate of cerebral spaces. In animals intoxicated with tetraethyl pyrophosphate, the maternal blood cholinesterase was rapidly reactivated after injection of 30 mg/kg of P2S, but both brain and blood cholinesterase activity of the fetuses stayed reduced. Administration of 60 mg/kg reactivated the enzyme also in fetuses. It is suggested that in cases of organophosphate poisoning in pregnant females, high doses of P2S should be administered in order to reach the fetus. Continuous slow infusion of the oxime appears to be the method of choice, as it also maintains a satisfactory constant plasma level.

N-methylpyridinium-2-nitrile has been identified in urine from rats and human beings treated with N-methylpyridinium-2-aldoxime. When injected into rats the nitrile is partially converted to inorganic thiocyanate and a metabolite possibly identical with metabolite X found in urine from oxime-treated animals. The nitrile was somewhat more toxic than the oxime.

2-Hydroxyiminomethyl-N-methylpyridinium methanesulphonate (P2S) is prepared by boiling pyridine-2-aldoxime with methyl methanesulphonate in benzene. It can be estimated both in water and in biological materials by measuring its ultra-vìolet absorption in alkaline solution. In aqueous solution it is slowly decomposed by heat or prolonged storage with some cyanide ion formation. The stability varies with pH, being optimal at pH 4–5. P2S can be satisfactorily sterilised by filtration through a “millipore” filter.

N-methylpyridinium-2-aldoxime methanesulphonate (P2S) was administered to rats and the urinary excretion of thiocyanate was determined by different methods. In addition to a small increase in thiocyanate excretion a metabolite was found which interfered with one of the test methods. It was concluded that formation of cyanide could not account for the toxicity of the oxime. Similar experiments on human beings showed no significant increase in thiocyanate excretion, but small amounts of an unknown metabolite were formed.

The soluble methanesulphonate of the oxime 2-hydroxyiminomethyl-N-methylpyridinium (P2S) has been used to treat animals poisoned with sarin or ethyl pyrophosphate. The effect of the size of the dose, and its time of administration in relation to poisoning, have been examined. This oxime is very efficient in conjunction with atropine when given either before or after poisoning. About 30 mg./kg. seems to be the optimum therapeutic dose of the methanesulphonate. The significance of this optimum is discussed in relation to the treatment of accidental poisoning by organophosphate insecticides in man.