- Xanthines studied via femtosecond fluorescence spectroscopy
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Xanthines represent a wide class of compounds closely related to the DNA bases adenine and guanine. Ubiquitous in the human body, they are capable of replacing natural bases in double helices and give rise to four-stranded structures. Although the use of their fluorescence for analytical purposes was proposed, their fluorescence properties have not been properly characterized so far. The present paper reports the first fluorescence study of xanthine solutions relying on femtosecond spectroscopy. Initially, we focus on 3-methylxanthine, showing that this compound exhibits non-exponential fluorescence decays with no significant dependence on the emission wavelength. The fluorescence quantum yield (3 × 10-4) and average decay time (0.9 ps) are slightly larger than those found for the DNA bases. Subsequently, we compare the dynamical fluorescence properties of seven mono-, di- and tri-methylated derivatives. Both the fluorescence decays and fluorescence anisotropies vary only weakly with the site and the degree of methylation. These findings are in line with theoretical predictions suggesting the involvement of several conical intersections in the relaxation of the lowest singlet excited state.
- Changenet-Barret, Pascale,Kovács, Lajos,Markovitsi, Dimitra,Gustavsson, Thomas
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- APPLICATIONS OF N6-SUBSTITUTED ADENOSINE DERIVATIVE AND N6-SUBSTITUTED ADENINE DERIVATIVE TO CALMING, HYPNOSES, CONVULSION RESISTANCE, EPILEPTIC RESISTANCE, PARKINSON DISEASE RESISTANCE, AND DEMENTIA PREVENTION AND TREATMENT
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PROBLEM TO BE SOLVED: To prepare analgesics, hypnotic agents, anticonvulsant agents, antiepileptics, antiparkinson drugs, dementia prophylactics, and health care food. SOLUTION: The present invention relates to an N6-substituted adenosine derivative and an N6-substituted adenine derivative selected from the group consisting of specific compounds. The present invention also relates to a pharmaceutical composition at least comprising a therapeutically effective amount of the compounds and a pharmaceutically acceptable carrier. The invention further relates to the compounds used in preparation of analgesics, hypnotic agents, anticonvulsant agents, antiepileptics, antiparkinson drugs, dementia prophylactics, and health care food. COPYRIGHT: (C)2016,JPO&INPIT
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Paragraph 0190
(2018/10/27)
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- N6-SUBSTITUTED ADENOSINE DERIVATIVES AND N6-SUBSTITUTED ADENINE DERIVATIVES AND USES THEREOF
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The present invention provides N6-substituted adenosine derivatives and N6-substituted adenine derivatives, manufacturing methods thereof, a pharmaceutical composition comprising the said compounds above, and uses of these compounds in manufacturing medicaments and health-care products for treating insomnia, convulsion, epilepsy, and Parkinson's diseases, and preventing and treating dementia.
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Paragraph 0390
(2013/03/26)
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- N6-SUBSTITUTED ADENOSINE DERIVATIVES, N6-SUBSTITUTED ADENINE DERIVATIVES AND USES THEREOF
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The present invention provides N6-substituted adenosine derivatives and N6-substituted adenine derivatives, manufacturing methods thereof, a pharmaceutical composition comprising the said compounds above, and uses of of these compounds in manufacturing medicaments and health-care products for treating insomnia, convulsion, epilepsy, and Parkinson's diseases, and preventing and treating dementia.
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Page/Page column 92-93
(2012/11/06)
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- Synthesis of the azathiopurine analogs
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The effective synthesis of the azathioprine analogs - 2-subsituted derivatives of 7-methyl-6-(1-methyl-4-nitroimidazol-5-ylthio)purines 5 has been achieved by the reaction of 2-subsituted 6-purinethiones 4 with 5-chloro-l-methyl-4-nitroimidazole in ethano
- Kowalska, Alicja,Pluta, Krystian
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p. 555 - 569
(2008/09/20)
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- Imidazo[2,1-i]purin-5-ones and related tricyclic water-soluble purine derivatives: Potent A2A- and A3-adenosine receptor antagonistst
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A series of tricyclic imidazo[2,1-i]purinones and ring-enlarged analogues derived from xanthine derivatives have been prepared as adenosine receptor (AR) antagonists. In comparison with xanthines, the tricyclic compounds exhibit increased water solubility due to a basic nitrogen atom, which can be protonated under physiological conditions. Substituents were introduced that confer high affinity for A2A or A3 ARs, respectively. A new capillary electrophoresis method was developed for the determination of the enantiomeric purity of selected chiral products using native and modified β-cyclodextrins as chiral discriminators. The compounds were investigated in radioligand binding assays at rat brain A1 and A2A ARs. Selected compounds were additionally investigated in radioligand binding assays at human recombinant A3 ARS and in functional studies (adenylate cyclase assays) at A1 ARs of rat fat cell membranes, A2A ARs of rat PC 12 cell membranes, and mouse A2B ARs of NIH 3T3 cell membranes. Structure-activity relationships were similar to those of corresponding xanthine derivatives. The 2-styrylimidazopurinones were less potent at A2A ARs as compared to 8-styrylxanthine derivatives. The most potent compound at A2A ARs was (S)-1,4-dimethyl-8-ethyl-2-styryl- imidazo[2,1-i]purinone (S-25) exhibiting a Ki value of 424 nM at rat A2A ARs. The compound was highly selective for A2A receptors vs A1 and A3 ARs. Selectivity vs A2B ARs, however, was low. Among the 1-unsubstituted 2-phenyl-imidazo[2,1-i]purin-5-one derivatives, very potent and highly selective antagonists for human A3 ARs were identified. The most potent A3 antagonist of the present series was (R)-4-methyl-8-ethyl-2-phenyl-imidazo[2,1-i]purin-5-one (R-24) exhibiting a Ki value of 2.3 nM and high selectivity for A3 receptors vs all other AR subtypes.
- Müller, Christa E.,Thorand, Mark,Qurishi, Ramatullah,Diekmann, Martina,Jacobson, Kenneth A.,Padgett, William L.,Daly, John W.
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p. 3440 - 3450
(2007/10/03)
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- N-Methyl Nucleosidase from Tea Leaves
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N-Methyl nucleoside hydrolase (N-methyl nucleosidase, N-MeNase), which hydrolyzes 7-methylxanthosine to produce 7-methylxanthine, was detected in tea-leaf extracts and separated from adenosine nucleosidase (ANase, EC 3.2.2.7) by DEAE-cellulose column chromatography.The optimum pH for the N-MeNase ranged from 8.0 to 8.5.The enzyme was strongly inhibited by EDTA.Inhibition by the hydrolysis products of 7-methylxanthosine and 7-methylinosine was also observed.The molecular weight was estimated to be about 55000 by gel-filtration.Among purine and N-methylpurine nucleosides, 3- and 7-methylpurine nucleosides were hydrolyzed preferentially by N-MeNase.On the other hand, ANase could not hydrolyze 7-methylxanthosine, although the enzyme showed high activity toward 7-methyladenosine.As a result, it is suggested that N-MeNase catalyzes the hydrolysis reaction of 7-methylxanthosine in the pathway of caffeine biosynthesis, whereas ANase is not directly concerned with it.
- Negishi, Osamu,Ozawa, Tetsuo,Imagawa, Hiroshi
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p. 169 - 176
(2007/10/02)
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- 2,6-Dialkoxy-7-methylpurines
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The preparation of unsymmetrical 2,6-dialkoxy-7-methylpurines (2), and 2-alkoxy-1,7-dialkyl-6-oxo-1,6-dihydropurines (5) is described.In contrast to 1 and 2, a facile thermal lactim-lactam rearrangement from hypoxanthines 5 and 7 into xanthines 6 was observed. - Keywords: Nucleophilic heteroaromatic substitution; thermal lactim-lactam rearrangement; Sigmatropic shifts; Dialkoxy-7H-purines; Dialkyl-1H(or 3H),7H-hypoxanthines; Trialkyl-7H-xanthines
- Kowalska, Alicja,Maslankiewicz, Andrzej,Syrek, Barbara,Cieplinski, Piotr
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p. 341 - 352
(2007/10/02)
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- ISOMERIZATION AND DEALKYLATION OF METHYLATED XANTHINIUM DERIVATIVES
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The isomerization or dealkylation of methylated xanthinium derivatives takes place with the participation of nucleophiles and is facilitated in the presence of a sterically hindered configuration.When heated, 7,9-dimethyl- and 1,7,9-trimethylxanthinium salts isomerize to theobromine and caffeine respectively.Under these conditions 3,7,9-trimethyl- and 1,3,7,9-tetramethylxanthinium salts are dealkylated.The 1,7,9- and 3,7,9-trimethylxanthinium betaines are isomerized quantitatively to caffeine.The role of the nucleophile under these conditions is played by the negatively charged fragment in the pyridine part of molecule.An intermolecular mechanism of rearrangement of the 3,7,9-trimethylxanthinium betaine is demonstrated.The sterically overloaded 1,3,8,9-tetramethylxanthine and 1,3,9-trimethyl-8-azaxanthine and not the charged compounds undergo rearrangement.In these cases the nucleophilic center is the doubly bonded N7 atom in the five-membered ring.
- Muravich-Aleksandr, Kh. L.,Kolesova, M. B.,Pernikova, V. G.,Smirnova, N. V.
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p. 562 - 567
(2007/10/02)
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- PHOTOCHEMISTRY OF PURINE 3-OXIDES IN HYDROXYLIC SOLVENTS
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UV irradiation of the potent oncogen hypoxanthine 3-oxide in aqueoous solution induces elimination of and rearrangement of the nitrogen-bound oxygen.The extent of each reaction shows a complex variation over the pH range 0-7.The variations in quantum yield for product formation are shown to result from the presence in the neutral molecule of tautomeric species with differing photochemistries that ionize in the excited state (pKa* ca. 3.5) just above the protonation pKa (1.2).The photochemical reactivity of each ionic and each tautomeric form was assigned by comparing the effect of pH changes between 0 and 11 on the quantum yields for formation of each photoproduct from hypoxanthine 3-oxide with those of two model compounds, 1-hydroxyhypoxanthine and 6-methoxypurine 3-oxide.Photoreduction of the 3-oxides occurs via the triplet state.This process has a relatively consistent low quantum yield (Φ=0.005 to 0.04) for most ionic and tautomeric forms of both purine 1-oxides and purine 3-oxides.Photorearrangement is a much more efficient process for purine 3-oxides (Φ=0.3) than for purine 1-oxides (Φ=0.04).
- Lam, Fuk L.,Parham, James C.
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p. 2371 - 2376
(2007/10/02)
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