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| 2. |
- Dahlqvist, Alexander, et al.
(author)
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Aminopyrimidine-galactose hybrids are highly selective galectin-3 inhibitors
- 2019
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 10:6, s. 913-925
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Journal article (peer-reviewed)abstract
- Galectins are a family of carbohydrate recognition proteins involved in, among other things, modulating cell signalling and cell-environment interactions, giving them roles in several pathologies like cancer and idiopathic lung fibrosis. Hence, developing new galectin inhibitors with high affinity and high selectivity is important to be able to target such diseases. Most existing galectin inhibitors have a disaccharide scaffold, but there has been success as of late in developing monogalactoside inhibitors such as α-arylthioglycosides. Here, we report aminopyrimidine-derivatised galactosides as good galectin-3 inhibitors with affinities down to 1.7 μM and a more than 300-fold selectivity over galectin-1. Mutant studies replacing Arg144 in galectin-3 with lysine and serine support the hypothesis that the binding of the derivatives involves interactions with Arg144. Molecular dynamics simulations converged to stable poses of the inhibitor aminopyrimidine moiety with polar interactions with Asp148 and Ser237, while the aryl-aminopyrimidine ring stacked onto the side chain of Arg144. Hence, combining an aminopyrimidine motif with a phenyl α-thiogalactoside motif offers an attractive route towards highly selective galectin-3 inhibitors.
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| 3. |
- Dutta, Suman, et al.
(author)
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Carba-LNA modified siRNAs targeting HIV-1 TAR region downregulate HIV-1 replication successfully with enhanced potency
- 2011
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 2:3, s. 206-216
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Journal article (peer-reviewed)abstract
- The conformationally-locked carbocyclic nucleosides carbaLNA ("jcLNA") (Gagnon et al., Biochemistry, 2010, 49, 10166; Srivastava et al., J. Am. Chem. Soc., 2007, 129, 8362; Xu et al., J. Org. Chem., 2009, 74, 6534; Zhou and Chattopadhyaya, J. Org. Chem., 2010, 75, 2341; Zhou et al., J. Org. Chem., 2009, 74, 118) are chemically engineered by fusing a carbocyclic ring at the C2' to C4' chiral centres in a stereospecific manner at the alpha-face of the pentose-sugar of the native nucleosides. The benefit of the chemically-modified oligonucleotides with the jcLNA scaffold has been shown to be their uniquely enhanced nuclease resistance in the blood serum as well as their improved RNase H recruitment capability to cleave the target RNA in the hybrid antisense-RNA duplex when used as an antisense agent, compared to those of locked nucleic acid (LNA) modified counterparts. Herein we report the relative inhibition efficiency of HIV-1 by jcLNA modified siRNAs targeting TAR region compared to those of the LNA counterparts, in that the former were found to exhibit improved silencing efficiency and displayed enhanced stability in human serum with negligible cytotoxicity compared to those of the latter. A single jcLNA substitution as the 3'-overhang of the guide strand displayed near native-like IC50 value (of 4.01 +/- 0.87 nM compared to the nearly two-fold higher IC50 value of 7.15 +/- 1.57 nM for LNA modified counterparts, and of the native siRNA of 1.84 +/- 0.16 nM) and significantly higher hp value for the stability in serum (11.9 h for jcLNA, 6.8 h for LNA and 3.0 h for native), thereby showing that the efficiency of jcLNA-modified-siRNAs is supported by stability without compromising the native-like efficiency and target RNA recognition and subsequent down-regulation. Amongst all the modified siRNAs so far used to target HIV-1 TAR region, the best IC50 value was obtained for the doubly-modified siRNA in which jcLNA substitution was introduced both at position 1 and 20 of the antisense strand (T-1 + T-20, i.e. jcLNA11 which showed IC50 value of 0.54 +/- 0.14 nM). The IC50 of this doubly-modified siRNA was more than three-fold lower than that of the native and two-fold lower than that of LNA modified counterpart, i.e. LNA12: IC50: 1.13 +/- 0.27 nM. Hence the strategy to chemically modify the native siRNAs by substitution with the jcLNA can be considered as a significant development, leading to both enhanced siRNA efficiency and serum stability over that of the native.
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| 4. |
- Dutta, Suman, et al.
(author)
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The R-diastereomer of 6 '-O-toluoyl-carba-LNA modification in the core region of siRNA leads to 24-times improved RNA silencing potency against the HIV-1 compared to its S-counterpart
- 2011
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 2:11, s. 1110-1119
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Journal article (peer-reviewed)abstract
- The modified siRNA with pure [6'(S)-O-(p-toluoyl)-7'(S)-methyl]-carba-LNA [6'(S)-O-toluoyl-jcLNA] at position T(13) displayed an IC(50) of 79.8 nM, which has been found to be nearly 24-times less potent as a HIV-1 RNAi silencing agent against TAR RNA than that of the corresponding pure [6'(R)-O-(ptoluoyl)-7'(S)-methyl]jcLNA [6'(R)-O-(p-toluoyl)-jcLNA] counterpart [IC(50) 3.3 nM]. The later [6'(R)-O-(p-toluoyl)-jcLNAl-modified siRNAs have been found to be nearly 2-fold more efficient as a silencing agent than the corresponding 6'-deoxy-jcLNA modified siRNA [IC(50) 8.1 nM], and also nearly 3-fold more effective as a silencing agent than that of LNA-modified siRNA [IC(50) 11.7 nM], thereby showing that the 6'-carbon center in the jcLNA-modified siRNA in the core region is relatively more exposed to the Ago protein in the RISC with a clear chirality preference for the siRNA cleavage reaction. It is noteworthy that the IC(50) of jcLNA-modified siRNAs are very comparable to that of the native siRNA [1.8 nM]. The jcLNA derivatized siRNAs, however, have a clear advantage of being, in general, considerably more stable in human serum. The main structural difference in duplexes of the antisense strand of the 6'(R or S)-O-(p-toluoyl)-jcLNA modified siRNA and target RNA duplex is found to be the spatial orientation of the 6'(R)-O-toluoyl group, which is exposed towards the edge of the duplex backbone, while the 6'(S) makes the minor groove relatively inaccessible for the Ago protein in the RISC. Clearly, any further C6'-modification in jcLNA-modified siRNAs with any hydrophobic group for tighter binding and cleavage or for cross-linking in the core region should preferably be done in the 6'(R)-stereochemistry.
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| 5. |
- Fritzson, Ingela, et al.
(author)
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N-Substituted salicylamides as selective malaria parasite dihydroorotate dehydrogenase inhibitors
- 2011
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2511 .- 2040-2503. ; 2:9, s. 895-898
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Journal article (peer-reviewed)abstract
- In our continuing program to develop Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) inhibitors, a series of N-substituted salicylamides were synthesized and their ability to selectively inhibit PfDHODH was examined. The synthetic program was based on 2-hydroxy-N-(2-phenylethyl)benzamide (1) that weakly inhibits both PfDHODH and human DHODH (hDHODH). Structure activity relationships were examined for developing derivatives. Selective PfDHODH inhibitors with improved potency were obtained by introducing a 2,2-diphenylethyl substitution on the salicylamidic nitrogen. Biological activity of the most potent compounds was confirmed on parasite infected cells in vitro.
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| 6. |
- Goldberg, Kristin, et al.
(author)
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Oxadiazole isomers : all bioisosteres are not created equal
- 2012
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 3:5, s. 600-604
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Journal article (peer-reviewed)abstract
- Two series of amino-substituted 1,2,4- and 1,3,4-oxadiazole matched compounds were evaluated and found to have significant differences in their various physical and pharmaceutical properties. Experimental and computational techniques suggested that variation in hydrogen bond acceptor and donor strength were responsible for these effects.
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| 7. |
- Gossas, Thomas, et al.
(author)
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The advantage of biosensor analysis over enzyme inhibition studies for slow dissociating inhibitors : characterization of hydroxamate-based matrix metalloproteinase-12 inhibitors
- 2013
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 4:2, s. 432-442
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Journal article (peer-reviewed)abstract
- The kinetic characteristics of hydroxamate-based inhibitors of matrix metalloproteinase (MMP)-12 were explored using an SPR biosensor-based assay and enzyme inhibition analysis. These high-affinity inhibitors were shown to dissociate very slowly from the enzyme-inhibitor complex while a carboxylate analogue had a much faster dissociation rate, verifying the importance of the hydroxamate group for the slow dissociation. Progress curve enzyme inhibition analysis confirmed that the hydroxamate compounds but not the carboxylate compound acted as time-dependent inhibitors. The slow dissociation excluded steady-state estimation of IC50-values and K-i values but also made K-i values from progress curve analysis unreliable. Although a full characterization of the inhibitors using biosensor analysis was limited by slow dissociation, it provided kinetic and mechanistic information of relevance for MMP drug discovery and avoided some pitfalls of conventional enzyme inhibition assays.
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| 8. |
- Haglund, Caroline, et al.
(author)
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Identification of an inhibitor of the ubiquitin-proteasome system that induces accumulation of polyubiquitinated proteins in the absence of blocking of proteasome function
- 2014
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 5:3, s. 376-385
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Journal article (peer-reviewed)abstract
- The ubiquitin-proteasome system (UPS) represents one of the most promising therapeutic targets in oncology to emerge in recent years. Here we used a combination of cytotoxic and image-based screening assays to identify a novel UPS inhibitor, designated HRF-3. HRF-3 evokes a gene expression profile similar to that of other characterized ups inhibitors, suggesting a common mechanism of action. Consistent with UPS inhibition, HRF-3 induced strong accumulation of polyubiquitinated proteins in cells. Surprisingly, HRF-3 induced only weak accumulation of two proteasome targeted reporter proteins, Ub(G76V)-YFP and ZsGreen-ODC. Consistent with this observation, HRF-3 did not inhibit proteasome proteolytic activity in an in vitro assay. Similar to a number of other UPS inhibitors, HRF-3 increased the expression of the redox-inducible protein Hmox-1. In distinction to the 20S inhibitor bortezomib, but similarly to two different p97/VCP inhibitors. HRF-3 did not elicit strong induction of the chaperone Hsp70B'. Finally, we show that HRF-3 is cytotoxic to a variety of cancer cell lines and ex vivo patient tumour cells, with the strongest activity observed in cells of leukemic/myeloma origin. Taken together our data show that HRF-3 induces polyubiquitin accumulation in the absence of efficient proteasomal blocking, and suggest that induction of oxidative stress is a common denominator of UPS inhibitors.
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| 9. |
- Kulén, Martina, et al.
(author)
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Methyl sulfonamide substituents improve the pharmacokinetic properties of bicyclic 2-pyridone based Chlamydia trachomatis inhibitors
- 2019
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In: MedChemComm. - : Royal Society of Chemistry. - 2040-2503 .- 2040-2511. ; 10:11, s. 1966-1987
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Journal article (peer-reviewed)abstract
- Chlamydia trachomatis infections are a global health problem and new approaches to treat C. trachomatis with drugs of high specificity would be valuable. A library of substituted ring fused 2-pyridones has been synthesized and evaluated for their ability to attenuate C. trachomatis infectivity. In vivo pharmacokinetic studies were performed, with the best candidates demonstrating that a C8-methylsulfonamide substituent improved pharmacokinetic properties important for oral administration. C8-Methyl sulfonamide analogue 30 inhibited C. trachomatis infectivity in low micromolar concentrations. Further pharmacokinetic evaluation at an oral dose of 10 mg kg(-1) showed an apparent bioavailability of 41%, compared to C8-cyclopropyl and -methoxy analogues which had negligible oral uptake. In vitro ADME (absorption, distribution, metabolism and excretion) testing of solubility and Caco-2 cell permeability revealed that both solubility and permeability is greatly improved with the C8-methyl sulfonamide 30, effectively moving it from BCS (Biopharmaceutical Classification System) class IV to II.
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| 10. |
- Lam, V. M., et al.
(author)
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Discovery of trace amine-associated receptor 1 ligands by molecular docking screening against a homology model
- 2015
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In: MedChemComm. - : Royal Society of Chemistry (RSC). - 2040-2503 .- 2040-2511. ; 6:12, s. 2216-2223
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Journal article (peer-reviewed)abstract
- Trace Amines (TA) are side-products of the synthesis of classical neurotransmitters within the brain. TAs exert their effect by binding to a family of G protein-coupled receptors termed Trace Amine-Associated Receptors (TAARs). TAAR1 is the best characterised member of this family and studies on TAAR1 have shown that this receptor is a negative regulator of dopamine transmission. Considering the limited number of pharmacological probes available for TAAR1, we aimed to identify novel ligands of this receptor using structure-based virtual screening. A homology model of TAAR1 was generated and over three million commercially available compounds were screened against the orthosteric site using molecular docking. Among the 42 top-ranked compounds that were tested in functional assays, three partial agonists with EC50 values ranging from 1 to 52 mu M were discovered. In addition, four potentially weak antagonists were identified. Ten analogs of the two most potent agonists from the screen were also evaluated and three of these displayed equal or greater activity compared to the parent compound. Several of the discovered ligands represent novel scaffolds and are thus promising starting points for development of new pharmacological tools for studying TAAR1 biology.
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