- Prediction of 3-hydroxypyridin-4-one (HPO) hydroxyl pKa values
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As an aid in optimising the design of 3-hydroxypyridin-4-ones (HPOs) intended for use as therapeutic Fe3+ chelating agents, various quantum mechanical (QM) and semi-empirical (QSAR) methods have been explored for predicting the pKa values of the hydroxyl groups in these compounds. Using a training set of 15 HPOs with known hydroxyl pKa values, reliable predictions are shown to be obtained with QM calculations using the B3LYP/6-31+G(d)/CPCM model chemistry (with Pauling radii, and water as solvent). With this methodology, the observed hydroxyl pKa values for the training set compound are closely matched by the predicted pKa values, with the correlation between the observed and predicted values giving r2 = 0.98. Predictions subsequently made by this method for a test set of 48 HPOs of known hydroxyl pKa values (11 of which were determined experimentally in this study), gave predicted pKa values accurate to within ±0.2 log units. In order to further investigate the predictive power of the method, two novel HPOs were synthesised and their hydroxyl pKa values were determined experimentally. Comparison of these predicted pKa values against the measured values gave absolute deviations of 0.13 (10.18 vs. 10.31) and 0.43 (5.58 vs. 5.15).
- Chen, Yu-Lin,Barlow, Dave J.,Kong, Xiao-Le,Ma, Yong-Min,Hider, Robert C.
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- BICYCLIC HETEROCYCLE DERIVATIVES HAVING SELECTIVE BACE1 INHIBITORY ACTIVITY
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The present invention provides a compound which has an effect of inhibiting amyloid β production, especially an effect of inhibiting selective BACE1, and which is useful as a therapeutic or prophylactic agent for diseases induced by production, secretion and/or deposition of amyloid β proteins. A compound of the formula (IA) or the like, wherein -A1- is alkylene optionally substituted with one or more halogen; R2 is substituted or unsubstituted alkyl or the like; R3 and R4 are each independently a hydrogen atom, halogen, alkyl or haloalkyl or the like; R5 is a hydrogen atom or halogen; A4 is N or CR6 wherein R6 is a hydrogen atom, halogen, or substituted or unsubstituted alkyl; A5 is NR7 or CR8R9; A6 is CR18 or N; R18 is a hydrogen atom; R7 is substituted or unsubstituted alkyl; R8 and R9 are each independently a hydrogen atom, halogen, alkyl or haloalkyl or the like; and Ring B is bicyclic ring; or a pharmaceutically acceptable salt thereof.
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Paragraph 0138
(2019/11/12)
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- Novel synthetic approach to fluoro- and amido-disubstituted 3-hydroxypyridin-4-ones
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Starting from fluoropyridines as a building block, with chelating functional groups being introduced, several fluoro- and amido-disubstituted 3-hydroxypyridin-4-ones have been synthesized with the intention of improving the pharmaceutical profile of 3-hydroxypyridin-4-ones.
- Ma, Yongmin,Hider, Robert C.
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- Design and synthesis of fluorinated iron chelators for metabolic study and brain uptake
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A range of fluorinated 3-hydroxypyridin-4-ones has been synthesized where fluorine or fluorinated substituent was attached at 2- or 5- position of the pyridine ring in order to improve chemical and biological properties of 3-hydroxypyridin-4-ones. The synthetic route is different from conventional counterparts where a functional group is introduced to a preformed 3-hydroxypyridin-4-one ring. Herein, we introduce a novel method which starts with a fluorine containing precursor and the two hydroxyl groups at 3- and 4- positions of the pyridine ring are introduced at a later stage. The pK a values of the free ligands and the affinity constants of their iron complexes demonstrate that the presence of fluorine dramatically alters the values. The distribution coefficient values of the free ligands and corresponding iron(III) complexes between 1-octanol and MOPS buffer (pH 7.4) are also influenced. Glucuronidation and oxidation studies of selected fluorinated 3-hydroxypyridin-4-ones demonstrate that some such fluorinated compounds have clear advantage over deferiprone in that they are metabolized more slowly. Blood-brain barrier permeability studies indicated that although lipophilicity influences the permeability it is not the only factor. Two of the selected seven fluorinated 3-hydroxypyridin-4-ones have improved brain distribution when compared with deferiprone.
- Ma, Yongmin,Roy, Sourav,Kong, Xiaole,Chen, Yulin,Liu, Dingyong,Hider, Robert C.
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supporting information; experimental part
p. 2185 - 2195
(2012/05/04)
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- Design and synthesis of fluorine-substituted 3-hydroxypyridin-4-ones
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The presence of fluorine in an organic molecule can dramatically alter its chemical and biological properties due to its unique characteristics. Several 2- and 5-fluorine-substituted 3-hydroxypyridin-4-ones have been synthesised with the intention of improving the pharmaceutical profile of deferiprone.
- Ma, Yong Min,Hider, Robert C.
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scheme or table
p. 5230 - 5233
(2010/11/03)
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- FLUORINATED PYRIDIN-4-0NES
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Metal chelating compounds of formula (I) are provided: or tautomers thereof or a pharmaceutically acceptable salt of either characterised in that R1 is selected from the group H and C1-6 alkyl R2, R4 and R5 are independently selected from the group H, C1-6 alkyl, Cl, F, -CHF2, CF3, -C(O)CF3, -CH(OH)CF3 and R6 R3 is selected from the group H, C1-6 alkyl and C1-6 acyl R6 is a group -C(O)-N(R7)(R8) R7 is selected from H and C1-6 alkyl and R8 is selected from H, C1-6 alkyl and a group -CH(R9CO)-N(R10XR11 ). R9 and R10 are independently selected from H, C1-6 alkyl and C1-10 aralkyl and R11 is selected from H and C1-6 alkyl, or R10 and R11 together with the nitrogen to which they are bonded form a 3-8 membered heterocyclic ring wherein at least one of R2, R4 and R5 is F. The compounds of the invention have reduced susceptibility to glucuronidation and microsomal oxidation as compared to current clinical compounds of the same class but in preferred forms have lower molecular weight and have blood brain barrier permeability.
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Page/Page column 22-23
(2009/10/18)
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