- Spectrophotometric investigation of 5-nitroso-6-aminouracil and its methyl derivative in methanol by selective complexation with bivalent metal ions
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6-Amino-5-nitrosouracils are synthesized by the condensation reaction of urea or N,N′-dimethyl urea, cyanoacetic acid and acetic anhydride followed by nitrosation reaction with sodium nitrite. The synthesized compounds are characterized by various spectroscopic techniques like FTIR, NMR, single crystal XRD, and UV–vis absorption spectroscopy. From a single-crystal X-ray crystallography study of DANU, it is found that the compound is crystalline with one water molecule. The binding properties of both compounds with various metal ions are studied using UV–vis spectroscopy, where ANU shows a colour change from colourless to yellow colour-forming complex with cobalt metal ion. While DANU shows a colour change from colourless to dark yellow forming complex with copper and nickel cation, respectively. These compounds showed the job's plots with Cu2+, Ni2+, and Co2+ in various stoichiometric ratios to form the respective metal complex. The association/binding constant (Ka) values are calculated by plotting Benesi–Hilderbrand plots of ANU with Co2+ ion and is found to be 9.524 × 102. Whereas, DANU with Cu2+, Ni2+ are found to be 3.956 × 103, 2.041 × 103, respectively. These cations may be used in metal ions complexation for the respective ligand. The LOD values for ANU-Co2+, DANU-Cu2+ & DANU-Ni2+ are obtained as 33.9428 μM, 93.8082 μM and 48.396 μM, respectively, whereas the LOQ values are found as 102.857 μM, 284.2675 μM and 146.653 μM, respectively.
- Das, Subrata,Hussain, Sahid,Kumar, Brajesh,Kumar, Pramanand,Sugunakara Rao, Mugada
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- Novel riboflavin-inspired conjugated bio-organic semiconductors
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Flavins are known to be extremely versatile, thus enabling routes to innumerable modifications in order to obtain desired properties. Thus, in the present paper, the group of bio-inspired conjugated materials based on the alloxazine core is synthetized using two efficient novel synthetic approaches providing relatively high reaction yields. The comprehensive characterization of the materials, in order to evaluate the properties and application potential, has shown that the modification of the initial alloxazine core with aromatic substituents allows fine tuning of the optical bandgap, position of electronic orbitals, absorption and emission properties. Interestingly, the compounds possess multichromophoric behavior, which is assumed to be the results of an intramolecular proton transfer.
- Richtar, Jan,Heinrichova, Patricie,Apaydin, Dogukan Hazar,Schmiedova, Veronika,Yumusak, Cigdem,Kovalenko, Alexander,Weiter, Martin,Sariciftci, Niyazi Serdar,Krajcovic, Jozef
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- Synthesis and evaluation of antitumour activities of novel fused tri-And tetracyclic uracil derivatives
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Simple one-pot syntheses of indenopyrrolopyrimidines and indolopyrrolopyrimidines were achieved via the cyclocondensation of 6-Aminouracils and, respectively, ninhydrin and isatin in the presence of catalytic amounts of glacial acetic acid. Similarly, 5,6-diaminouracil derivatives were used as starting materials for the synthesis of indenopteridines and indolopteridines via their reaction with ninhydrin and isatin, respectively. The synthesised compounds were evaluated for antitumour activity against a human hepatocellular carcinoma cell line (HepG2), some showing antitumour activity comparable with 5-fluorouracil and imatinib.
- Elkalyoubi, Samar,Fayed, Eman
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p. 771 - 777
(2017/01/03)
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- Synthesis of purine antiviral agents, hypoxanthine and 6-mercaptopurine
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Some potentially biologically active 6-substituted purine derivatives have been synthesized from simple organic reagents. The reaction of urea with ethyl cyanoacetate gave 6-aminopyrimidine-2,4-dione which was converted in two steps into purine derivative, xanthine. The latter was treated with formamide at 200°C to obtain hypoxanthine. The chlorination of hypoxanthine with POCl3 gave 6-chloropurine which was converted into 6-mercaptopurine via reaction with thiourea in acetonitrile, followed by treatment with boiling ethanol.
- Sariri,Khalili
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p. 1053 - 1055
(2007/10/03)
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- Synthesis of Paraxanthine Analogs (1,7-Disubstituted Xanthines) and Other Xanthines Unsubstituted at the 3-Position: Structure-Activity Relationships at Adenosine Receptors
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Synthetic procedures for the preparation of various 3-unsubstituted xanthines, including paraxanthine analogs (1,7-disubstituted xanthines) and 1,8-disubstituted xanthines, were developed.Sylylation of 1-substituted xanthines followed by alkylation at the 7-position provides a facile route to paraxanthine analogs.Regioselective alkylation of tris(trimethylsilyl)-6-aminouracil provides 3-substituted 6-aminouracils, which are converted to 1,8-disubstituted xanthines by standard procedures.The ring closure of 3-substituted 5-cyclopentanecarboxamido- and 5-(benzoylamino)-6-aminouracils requires drastic reaction conditions.Affinity for brain A1 and A2 adenosine receptors was determined in binding assays for these and other xanthines with substituents in 1-, 3-, 7-, 8-, and 9-positions.Substitution at the 1-position was necessary for high affinity at adenosine receptors. 1,3-Disubstituted xanthines generally had higher affinity than 1,7-disubstituted xanthines. 1,8-Disubstituted xanthines had high affinity for adenosine receptors; some were highly selective for A1 receptors.
- Mueller, Christa E.,Shi, Dan,Manning, Malcolm,Daly, John W.
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p. 3341 - 3349
(2007/10/02)
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