- Structure-based design of guanosine analogue inhibitors targeting GTP cyclohydrolase IB towards a new class of antibiotics
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GTP cyclohydrolase (GCYH-I) is an enzyme in the folate biosynthesis pathway that has not been previously exploited as an antibiotic target, although several pathogens including N. gonorrhoeae use a form of the enzyme GCYH-IB that is structurally distinct from the human homologue GCYH-IA. A comparison of the crystal structures of GCYH-IA and -IB with the nM inhibitor 8-oxo-GTP bound shows that the active site of GCYH-IB is larger and differently shaped. Based on this structural information, we designed and synthesized a small set of 8-oxo-G derivatives with ether linkages at O6 and O8 expected to displace water molecules from the expanded active site of GCYH-IB. The most potent of these compounds, G3, is selective for GCYH-IB, supporting the premise that potent and selective inhibitors of GCYH-IB could constitute a new class of small molecule antibiotics.
- Haque, Ayesha,Hecht, David A.,Paranagama, Naduni,Purse, Byron W.,Samaan, George N.,Swairjo, Manal A.
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supporting information
(2019/12/09)
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- Kinetics and mechanism of the defluorination of 8-fluoropurine nucleosides in basic and acidic media
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For investigating the stability of C(8)-fluorine bond in 8-fluoropurine nucleosides some protected 8-fluoroguanosine, 8-fluoroinosine and 8-fluoroadenosine derivatives were prepared by direct fluorination of acetyl-protected purine nucleosides with elemental fluorine in solvents such as chloroform, acetonitrile and nitromethane. Fluorination reactions conducted in chloroform medium gave better yields of 8-fluoropurines. The fluorination yields were slightly lower when acetonitrile or nitromethane was used as solvent, but the product purification was found to be much easier. When the synthesized, protected fluoronucleosides were subjected to standard basic (NH3 in methanol or 2-propanol) and acidic (HCl in methanol) deprotection conditions relevant to nucleoside chemistry, an efficient defluorination reaction took place. The kinetics of these defluorination reactions were conveniently followed, under pseudo-first-order reaction conditions, using 19F NMR spectroscopy. 1H NMR, LC-MS and mass spectroscopy identified the products of the kinetic reaction mixtures. The defluorination reaction rate constants (kobs) in basic media depended upon the electron density at C(8) while the kobs data in acidic medium were determined by the pKa of N7. An addition-elimination based mechanism (SNAr) has been proposed for the defluorination reactions of these 8-fluoropurine nucleosides.
- Liu, Jie,Barrio, Jorge R.,Satyamurthy, Nagichettiar
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p. 1175 - 1187
(2008/12/20)
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- 8-Substituted guanosine and 2'-deoxyguanosine derivatives as potential inducers of the differentiation of Friend erythroleukemia cells
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A variety of 8-substituted guanosine and 2'-deoxyguanosine derivatives were synthesized and tested as inducers of the differentiation of Friend murine erythroleukemia cells in culture. The most active agents in the guanosine series were 8-substituted -N(CH3)2, -NHCH3, -NH2, -OH, and -SO2CH3, which caused 68, 42, 34, 33, and 30% of erythroleukemia cells to attain benzidine positivity, a functional measure of maturation, at concentrations of 5, 1, 0.4, 5, and 5 mM, respectively. The 8-OH derivative of the 2'-deoxyguanosine series produced comparable activity, causing 62% benzidine-positive cells at a level of 0.2 mM. These findings indicate that 8-substituted analogues of guanosine and 2'-deoxyguanosine have the potential to terminate leukemia cell proliferation through conversion to end-stage differentiated cells.
- Lin,Cheng,Ishiguro,Sartorelli
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p. 1194 - 1198
(2007/10/02)
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