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At least 19 recordsLinked to original sources
PubMed2005

Hydrogen-bonded chains in isostructural 5-methyl-2-(4-methylphenyl)-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine, 2-(4-chlorophenyl)-5-methyl-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine and 2-(4-bromophenyl)-5-methyl-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine, and sheets of pi-stacked hydrogen-bonded chains in 2-(4-methoxyphenyl)-5-methyl-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine.

5-methyl-2-(4-methylphenyl)-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine, C17H17N3, 2-(4-chlorophenyl)-5-methyl-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine, C16H14ClN3, and 2-(4-bromophenyl)-5-methyl-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine, C16H14BrN3, are isostructural; in each compound, the molecules are linked into chains by a single C-H...pi(arene) hydrogen bond. Molecules of 2-(4-methoxyphenyl)-5-methyl-7,8-dihydro-6H-cyclopenta[g]pyrazolo[1,5-a]pyrimidine, C17H17N3O, are linked by a single C-H...N hydrogen bond into chains, which are themselves linked into sheets by a pi-pi stacking interaction.

Crystallography, X-Ray↗
PubMed2001

Novel pyrimidine-bridged platinum(II) complexes: multinuclear magnetic resonance spectroscopy and crystal structures of (NR4)2[(PtCl3)2(mu-pyrimidine)] and cis- and trans-[Pt(R2SO)Cl2]2(mu-pyrimidine).

Two new types of pyrimidine-bridged Pt(II) complexes, (NR4)2[(PtCl3)2(mu-pm)] and cis- and trans-[Pt(R2SO)Cl2]2(mu-pm) where pm = pyrimidine, were synthesized and characterized by IR and multinuclear magnetic resonance spectroscopies and by crystallographic methods. Compounds with dimethylsulfoxide, tetramethylenesulfoxide, di-n-propylsulfoxide (DPrSO), di-n-butylsulfoxide (DBuSO), dibenzylsulfoxide (DBzSO), and diphenylsulfoxide were studied. The aqueous reaction of K2PtCl4 with pyrimidine produced the [(PtCl3)2(mu-pm)](2-) ions, which can be precipitated with a NR4(+) salt. The aqueous reaction of K[Pt(R2SO)Cl3] with pyrimidine in a 2:1 ratio produced the dinuclear species trans-[Pt(R2SO)Cl2]2(mu-pm). With DBuSO and DBzSO, the analogous cis isomers were also obtained. The 195Pt NMR resonances of the trans dimeric complexes were observed at higher field (av -3088 ppm) than the cis compounds (av -2948 ppm). The 195Pt coupling constants with the atoms of pyrimidine 3J(195Pt-1H) and 3J(195Pt-13C) are larger in the cis configuration than in the trans analogues. The crystal structures of two ionic complexes, (NR4)2[(PtCl3)2(mu-pm)] (R = Me and n-Bu), and of three mixed-ligands dimers, trans-[Pt(R2SO)Cl2]2(mu-pm) (R2SO = DMSO, DPrSO) and cis-Pt(DBuSO)Cl2]2(mu-pm), were determined.

Carbon Isotopes↗
PubMed1980

Pyrimidine nucleotide pool changes during the cell cycle and quiescence. Pyrimidine excretion and metabolic isolation of the pyrimidine mononucleoside polyphosphate pool.

We have measured the pyrimidine nucleotide contents of the culture fluid, acid-soluble fraction, and acid-insoluble fraction of cultures of hamster embryo fibroblasts (third subculture) through the final two divisions of growth in culture. The cells show a growth delay between the penultimate and ultimate division periods and a concomitant biochemical synchrony of pyrimidine metabolism. The cells exhibit normal excretion of pyrimidine nucleotides beginning with the ultimate division cycle. This excretion results from the net breakdown of ribonucleic acid and a cell-regulated maximum for pyrimidine mononucleoside polyphosphate content. This upper limit for the pyrimidine nucleoside polyphosphate content is not a steady state phenomenon but rather an absence of both synthesis and utilization. The hamster embryo fibroblast exhibits a directed flow of salvage uridine for ribonucleic acid synthesis. We show that de novo synthetic uridine 5'-monophosphate also can be used for ribonucleic acid synthesis without prior entry into the cytoplasmic uridine nucleoside polyphosphate pool. During attachment and first division salvage uridine does enter the cytoplasmic nucleotide pool. The properties of the cytidine pools differ from the uridine pools in specific activity and levels of cytidine, due to turnover of the terminal C-C-A of cytoplasmic transfer ribonucleic acid and the delay in conversion of of nonradioactive de novo synthetic uridine 5'-monophosphate to cytidine 5'-triphosphate. The partial synchrony in these cultures has been used as a temporal marker of the observed events.

Animals↗
PubMed1989

Synthesis of substituted pyrimidines, pyrazole[3,4-d]pyrimidines and imidazo[4,5-d]pyrimidines and evaluation of their antifungal activity.

Some pyrimidines, pyrazolo[3,4-d]pyrimidines and imidazo[4,5-d]pyrimidines bearing the 5-nitro- and 5-aminothienyl-2-sulfide functionalities on the pyrimidine nucleus were synthesized and evaluated for their antifungal activity against several strains of yeasts and dermatophytes. 4-Amino-2-pyrimidinyl-5'-nitro-2'-thienylsulfide (Va) resulted active against both yeasts and dermatophytes (about 30 fold less potent than Miconazole). Compds. (II b), (V b) and (VIII b) showed only a slight activity against dermatophytes, while the other compounds were inactive.

Acetylation↗
PubMed2003

Benzylation and nitrosation of 4-amino-2-(methylsulfanyl)pyrimidin-6(1H)-one: two P2(1)/c polymorphs of 4-amino-1-benzyl-2-(methylsulfanyl)pyrimidin-6(1H)-one with Z' = 1 and 2, 4-amino-6-benzyloxy-2-(methylsulfanyl)pyrimidine and 4-amino-1-benzyl-2-(methylsulfanyl)-5-nitrosopyrimidin-6(1H)-one all give different hydrogen-bonded supramolecular structures.

4-Amino-1-benzyl-2-(methylsulfanyl)pyrimidin-6(1H)-one, C(12)H(13)N(3)OS, crystallizes in two polymorphic forms, both having space group P2(1)/c, with Z' = 1 for form (I) and Z' = 2 for form (II). In (I), the molecules are linked by a single N-H.O hydrogen bond into simple C(6) chains, which are themselves linked into sheets by aromatic pi-pi interactions, while in (II), chains of edge-fused R(4)(2)(8) and R(4)(4)(24) rings are generated by four distinct N-H.O hydrogen bonds. In 4-amino-1-benzyl-2-(methylsulfanyl)-5-nitrosopyrimidin-6(1H)-one, C(12)H(12)N(4)O(2)S, (III), where Z' = 2, two independent three-centre N-H.(N,O) hydrogen bonds generate a C(5)C(6)[R(1)(2)(5)] chain of rings. In 4-amino-6-benzyloxy-2-(methylsulfanyl)pyrimidine, C(12)H(13)N(3)OS, (IV), which is isomeric with (I) and (II), a combination of N-H.N and N-H.O hydrogen bonds generates a sheet of alternating R(2)(2)(8) and R(6)(6)(28) rings.

Journal Article↗
PubMed2003

Pyrimidines. Part II: Synthesis of novel pyrimidines, 1,2,4-triazolo[4,3-a]pyrimidin-7-ones and pyrimidino[2,1-c][1,2,4]triazin-8-ones for their antimicrobial and anticancer activities.

Five main classes of novel pyrimidine derivatives have been synthesized; namely 6-substituted phenyl-5-cyano-3-methyl-2-phenacylhydrazino-3,4-dihydropyrimidin-4-ones 4a-e; 6-substituted phenyl-2-arylidene hydra-zino-5-cyano-3-methyl-3,4-dihydropyrimidin-4-ones 5a-i; 6-substituted phenyl-2-acylhydrazino-5-cyano-3-methyl-3,4-dihydropyrimidin-4-ones 7a-d, 8a-e and 9a-c; three novel series of 1,2,4-triazolo[4,3-a] pyrimidones 10a,b, 11a-d and 12a-d and 6-substituted phenyl-7-cyano-9-methyl-3-phenyl or 4-chlorophenyl-4,9-dihydropyrimido[2,1-c][1,2,4] triazin-8-ones 13a-c. Besides, the azide compound 2-azido-5-cyano-3-methyl-6-phenyl-3,4-dihydropyrimidin-4-one 6 was also synthesized. The prepared compounds were tested for antimicrobial and anticancer activity. Compounds 4b and 4d showed promising activity against Escherichia coli. Compounds 3c, 5c, 5e, 5g and 7b were active in the three cell line antitumor one dose primary assay and were evaluated in the 60 human tumor full panel cell line invitro screening. Compound 5c showed promising activity against all types of leukemia especially leukemia K-562 and leukemia SR with GI50 = 1.61 and 2.63 mmol/l respectively.

Anti-Infective Agents↗
PubMed1987

Metabolism of pyrimidine bases and nucleosides by pyrimidine-nucleoside phosphorylases in cultured human lymphoid cells.

The anabolism of pyrimidine ribo- and deoxyribonucleosides from uracil and thymine was investigated in phytohemagglutinin-stimulated human peripheral blood lymphocytes and in a Burkitt's lymphoma-derived cell line (Raji). We studied the ability of these cells to synthesize pyrimidine nucleosides by ribo- and deoxyribosyl transfer between pyrimidine bases or nucleosides and the purine nucleosides inosine and deoxyinosine as donors of ribose 1-phosphate and deoxyribose 1-phosphate, respectively: these reactions involve the activities of purine-nucleoside phosphorylase, and of the two pyrimidine-nucleoside phosphorylases (uridine phosphorylase and thymidine phosphorylase). The ability of the cells to synthesize uridine was estimated from their ability to grow on uridine precursors in the presence of an inhibitor of pyrimidine de novo synthesis (pyrazofurin). Their ability to synthesize thymidine and deoxyuridine was estimated from the inhibition of the incorporation of radiolabelled thymidine in cells cultured in the presence of unlabelled precursors. In addition to these studies on intact cells, we determined the activities of purine- and pyrimidine-nucleoside phosphorylases in cell extracts. Our results show that Raji cells efficiently metabolize preformed uridine, deoxyuridine and thymidine, are unable to salvage pyrimidine bases, and possess a low uridine phosphorylase activity and markedly decreased (about 1% of peripheral blood lymphocytes) thymidine phosphorylase activity. Lymphocytes have higher pyrimidine-nucleoside phosphorylases activities, they can synthesize deoxyuridine and thymidine from bases, but at high an non-physiological concentrations of precursors. Neither type of cell is able to salvage uracil into uridine. These results suggest that pyrimidine-nucleoside phosphorylases have a catabolic, rather than an anabolic, role in human lymphoid cells. The facts that, compared to peripheral blood lymphocytes, lymphoblasts possess decreased pyrimidine-nucleoside phosphorylases activities, and, on the other hand, more efficiently salvage pyrimidine nucleosides, are consistent with a greater need of these rapidly proliferating cells for pyrimidine nucleotides.

Cells, Cultured↗
PubMed2004

Synthesis of classical, three-carbon-bridged 5-substituted furo[2,3-d]pyrimidine and 6-substituted pyrrolo[2,3-d]pyrimidine analogues as antifolates.

Bridge homologation of the previously reported classical two-carbon-bridged antifolates, a 5-substituted 2,4-diaminofuro[2,3-d]pyrimidine (1) [which is a 6-regioisomer of LY231514 (Alimta)] and a 6-subsituted 2-amino-4-oxopyrrolo[2,3-d]pyrimidine, afforded the three-carbon-bridged antifolates analogues 4 and 5, with enhanced inhibitory activity against tumor cells in culture (EC(50) values in the 10(-8)-10(-7) M range or less). These two analogues were synthesized via a 10-step synthetic sequence starting from methyl 4-bromobenzoate (14), which was elaborated to the alpha-chloromethyl ketone (8) followed by condensation with 2,6-diamino-pyrimidin-4-one (7) to afford the substituted furo[2,3-d]pyrimidine 9 and the pyrrolo[2,3-d]pyrimidine 10. Subsequent coupling of each regioisomer with diethyl-l-glutamate followed by saponification afforded 4 and 5. The biological results indicate that elongation of the C8-C9 bridge of the classical 5-substituted 2,4-diaminofuro[2,3-d]pyrimidine and 6-substituted 2-amino-4-oxopyrrolo[2,3-d]pyrimidine are highly conducive to antitumor activity in vitro, despite a lack of increase in inhibitory activity against the target enzymes. This supports our original hypothesis that truncation of the B-ring of a highly potent 6-6 ring system to a 6-5 ring system can be compensated by bridge homologation to restore the overall length of the molecule.

Antimetabolites, Antineoplastic↗
PubMed1961

Utilization of pyrimidines and pyrimidine deoxynucleosides by Thermobacterium acidophilum (Lactobacillus acidophilus).

Løvtrup, Søren (University of Göteborg, Sweden) and David Shugar. Utilization of pyrimidines and pyrimidine deoxynucleosides by Thermobacterium acidophilum (Lactobacillus acid-ophilus). J. Bacteriol. 82:623-631. 1961.-The utilization of pyrimidine deoxynucleosides was investigated by means of deoxyribosides of unnatural pyrimidines, especially by halogen-substituted uracil derivatives. All investigated deoxyribosides could be used, except that of N-methylthymidine. It was concluded that this substance cannot be a substrate for the enzyme trans-N-deoxyribosylase, which has been shown to be active in the utilization of deoxyribosides in this microorganism. With uracil as the only pyrimidine source, the halogen-substituted deoxyuridines had a certain inhibitory effect on growth. Contrary to previous findings, it was observed that normal growth occurs in the presence of thymine as the only pyrimidine source. The utilization of this substance is less efficient than that of uracil; a 1:10 dilution leads to a decrease in the extent of growth with the former, but not with the latter. From these results, complemented with experiments in which halogen-substituted uracil derivatives and the corresponding ribosides or deoxyribosides were used as inhibitors, it has been possible to account for most of the metabolic interconversions of pyrimidines in the investigated microorganism.

Lactobacillus↗
PubMed1979

Metabolism of pyrazolo(3,4-d)pyrimidines in Leishmania braziliensis and Leishmania donovani. Allopurinol, oxipurinol, and 4-aminopyrazolo(3,4-d)pyrimidine.

Leishmania donovani and Leishmania braziliensis grown in culture formed millimolar concentrations of allopurinol ribonucleoside 5'-monophosphate from [6-14C]allopurinol. In addition, allopurinol 1-ribonucleoside, oxipurinol riboside 5'-monophosphate, and three new metabolites of allopurinol, namely, 4-aminopyrazolo(3,4-d)pyrimidine ribonucleoside 5'-monophosphate and the corresponding di- and triphosphates (1-ribosyl 4-aminopyrazolo(3,4-d)pyrimidine 5'-diphosphate and 1-ribosyl 4-aminopyrazolo(3,4-d)pyrimidine 5'-triphosphate) were identified in the parasitic cells. They were formed via a unique amination reaction from 1-ribosyl allopurinol 5'-phosphate, analogous to the conversion of IMP to AMP. [6-14C]Allopurinol was incorporated into RNA of L. donovani in the form of 4-aminopyrazolo(3,4-d)pyrimidine. Adenine reversed the growth inhibition of allopurinol and prevented its metabolism to all of the ribonucleotide metabolites. L. donovani was 2- to 4-fold more active in its metabolism of allopurinol to ribonucleotides than L. braziliensis. 4-Aminopyrazolo(3,4-d)pyrimidine inhibited cell growth and resulted in high intracellular levels of 1-ribosyl allopurinol 5'-phosphate and smaller amounts of the 4-aminopyrazolo(3,4-d)pyrimidine ribonucleotides. The metabolism of allopurinol to 4-aminopyrazolo(3,4-d)pyrimidine ribonucleotides and its resultant cytotoxicity occurs in these parasitic protozoans, but not in mammalian cells.

Adenine↗
PubMed1997

Pyrimidine nucleotidases from human erythrocyte possess phosphotransferase activities specific for pyrimidine nucleotides.

Two cytoplasmic forms of pyrimidine nucleotidase (PN-I and PN-II) have been purified from human erythrocytes to apparent homogeneity and partially characterized. They preferentially hydrolyse pyrimidine 5'-monophosphates and 3'-monophosphates respectively. PN-I and PN-II operate as interconverting activities, capable of transferring the phosphate from the pyrimidine nucleoside monophosphate donor(s) to various nucleoside acceptors, including important drugs like 3'-azido-3'-deoxy-thymidine (AZT), cytosine-beta-D-arabinofuranoside (AraC) and 5-fluoro-2'-deoxy-uridine (5FdUrd), pyrimidine analogues widely used in chemotherapy. Kinetic analysis showed linear behaviour for both PN-I and PN-II. PN-I phosphotransferase activity revealed higher affinity for oxynucleosides with respect to deoxy-nucleosides, whereas the contrary seems to be true for PN-II. These results show for the first time that soluble pyrimidine nucleotidases are endowed with pyrimidine-specific phosphotransferase activity.

Erythrocytes↗
PubMed1993

Human nucleotide excision nuclease incises synthetic double-stranded DNA containing a pyrimidine dimer at the fourth phosphodiester linkage 3' to the pyrimidine dimer.

Linear 75mer double-stranded DNA containing a single pyrimidine dimer at a unique site was used to investigate pyrimidine dimer-dependent endonuclease activities from human cells. HeLaS3 cell extract incised the target DNA at the fourth phosphodiester linkage 3' to the pyrimidine dimer. However, incision of the DNA at 5' side of the pyrimidine dimer was not detected. The incision was also detected in cell extracts prepared from other excision repair-proficient cell lines. Incision was detected only on the DNA strand containing a pyrimidine dimer in the presence of poly(dI-dC)-poly(dI- dC) double strand. The reaction required Mg2+ but not ATP. The extract prepared from excision repair-deficient xeroderma pigmentosum (XP) cells belonging to the complementation group A was unable to incise the DNA. Extracts from the complementation groups C, D, and G incised the DNA very weakly at the third phosphodiester linkage 3' to the pyrimidine dimer, a site different from that incised by normal human cell extract. These results suggest that the observed incision reaction is associated with excision repair in human cells.

Adenosine Triphosphate↗
PubMed1968

Biosynthesis of the pyrimidine moiety of thiamine. A new route of pyrimidine biosynthesis involving purine intermediates.

1. The pattern of distribution on the purine pathway of mutants of Salmonella typhimurium LT2 that had the double growth requirement for a purine plus the pyrimidine moiety of thiamine (ath mutants) indicated that purines and the pyrimidine moiety of thiamine share the early part of their biosynthetic pathways, and that 4-aminoimidazole ribonucleotide (AIR) is the last common intermediate. Two mutants that at first appeared anomalous were further investigated and found not to affect this deduction. 2. The ribonucleoside form of AIR (AIR(s)) satisfied the requirements both for a purine and for the pyrimidine moiety of thiamine of an ath mutant. 3. Methionine was required for the conversion of AIR into the pyrimidine moiety. 4. Radioactive AIR(s) was converted into radioactive pyrimidine moiety by an ath mutant without significant dilution of specific radioactivity. 5. Possible mechanisms for pyrimidine-moiety biosynthesis from AIR are discussed.

Autoradiography↗
PubMed1994

Evidence from CD spectra that d(purine).r(pyrimidine) and r(purine).d(pyrimidine) hybrids are in different structural classes.

CD spectra and difference CD spectra of four d(oligopurine).r(oligopyrimidine) and four r(oligopurine).d(oligopyrimidine) hybrid duplexes containing mixed A.T(U) and G.C base pairs were compared with the spectra of four DNA.DNA and four RNA.RNA oligomer duplexes of similar repeating sequences. The 16 duplexes were formed by mixing oligomers that were 24 nucleotides long. The buffer was 0.05 M Na+ (phosphate), pH 7.0. DNA.DNA and RNA.RNA oligomer duplexes were used as reference B-form and A-form structures. We found that the CD spectra of d(purine).r(pyrimidine) and r(purine).d(pyrimidine) hybrid duplexes were different from the CD spectra of either DNA.DNA or RNA.RNA duplexes. The data suggested that these hybrids have intermediate structures between A-form RNA and B-form DNA structures. The CD spectra of d(purine).r(pyrimidine) and r(purine).d(pyrimidine) hybrid duplexes were different from each other, but the hybrids in each class had consistent CD spectra as indicated by nearest-neighbor comparisons. Thus, it appeared that the two types of hybrids belonged to different structural classes. The negative 210 nm band found in difference CD spectra was correlated with the presence of an r(purine) strand in the hybrid duplexes. The melting temperatures (Tm values) of these hybrids were compared with the Tm values of the DNA.DNA and RNA.RNA duplexes. The order of the thermal stability was: RNA.RNA duplex > r(purine).d(pyrimidine) hybrid > DNA.DNA duplex > d(purine).r(pyrimidine) hybrid, when comparing analogous sequences.

Base Composition↗