Design, synthesis, and structure-activity relationships of pyridoquinazolinecarboxamides as RNA polymerase I inhibitors.
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ABSTRACT: RNA polymerase I (Pol I) is a dedicated polymerase that transcribes the 45S ribosomal (r) RNA precursor. The 45S rRNA precursor is subsequently processed into the mature 5.8S, 18S, and 28S rRNAs and assembled into ribosomes in the nucleolus. Pol I activity is commonly deregulated in human cancers. On the basis of the discovery of lead molecule BMH-21, a series of pyridoquinazolinecarboxamides have been evaluated as inhibitors of Pol I and activators of the destruction of RPA194, the Pol I large catalytic subunit protein. Structure-activity relationships in assays of nucleolar stress and cell viability demonstrate key pharmacophores and their physicochemical properties required for potent activation of Pol I stress and cytotoxicity. This work identifies a set of bioactive compounds that potently cause RPA194 degradation that function in a tightly constrained chemical space. This work has yielded novel derivatives that contribute to the development of Pol I inhibitory cancer therapeutic strategies.
Project description:The measles virus (MeV), a member of the paramyxovirus family, is an important cause of pediatric morbidity and mortality worldwide. In an effort to provide therapeutic treatments for improved measles management, we previously identified a small, non-nucleoside organic inhibitor of the viral RNA-dependent RNA polymerase by means of high-throughput screening. Subsequent structure-activity relationship (SAR) studies around the corresponding pyrazole carboxamide scaffold led to the discovery of 2 (AS-136a), a first generation lead with low nanomolar potency against life MeV and attractive physical properties suitable for development. However, its poor water solubility and low oral bioavailability (F) in rat suggested that the lead could benefit from further SAR studies to improve the biophysical characteristics of the compound. Optimization of in vitro potency and aqueous solubility led to the discovery of 2o (ERDRP-00519), a potent inhibitor of MeV (EC(50) = 60 nM) with an aqueous solubility of approximately 60 ?g/mL. The agent shows a 10-fold exposure (AUC/C(max)) increase in the rat model relative to 2, displays near dose proportionality in the range of 10-50 mg/kg, and exhibits good oral bioavailability (F = 39%). The significant solubility increase appears linked to the improved oral bioavailability.
Project description:Bacterial RNA polymerase (RNAP) is essential for transcription and is an antibacterial target for small molecule inhibitors. The binding region of myxopyronin B (MyxB), a bacterial RNAP inhibitor, offers the possibility of new inhibitor design. The molecular design program SPROUT has been used in conjunction with the X-ray cocrystal structure of Thermus thermophilus RNAP with MyxB to design novel inhibitors based on a substituted pyridyl-benzamide scaffold. A series of molecules, with molecular masses <350 Da, have been prepared using a simple synthetic approach. A number of these compounds inhibited Escherichia coli RNAP.
Project description:The template-directed synthesis of RNA played an important role in the transition from prebiotic chemistry to the beginnings of RNA based life, but the mechanism of RNA copying chemistry is incompletely understood. We measured the kinetics of template copying with a set of primers with modified 3'-nucleotides and determined the crystal structures of these modified nucleotides in the context of a primer/template/substrate-analog complex. pH-rate profiles and solvent isotope effects show that deprotonation of the primer 3'-hydroxyl occurs prior to the rate limiting step, the attack of the alkoxide on the activated phosphate of the incoming nucleotide. The analogs with a 3 E ribose conformation show the fastest formation of 3'-5' phosphodiester bonds. Among those derivatives, the reaction rate is strongly correlated with the electronegativity of the 2'-substituent. We interpret our results in terms of differences in steric bulk and charge distribution in the ground vs. transition states.
Project description:Protein lysine methyltransferase G9a, which catalyzes methylation of lysine 9 of histone H3 (H3K9) and lysine 373 (K373) of p53, is overexpressed in human cancers. Genetic knockdown of G9a inhibits cancer cell growth, and the dimethylation of p53 K373 results in the inactivation of p53. Initial SAR exploration of the 2,4-diamino-6,7-dimethoxyquinazoline template represented by 3a (BIX01294), a selective small molecule inhibitor of G9a and GLP, led to the discovery of 10 (UNC0224) as a potent G9a inhibitor with excellent selectivity. A high resolution X-ray crystal structure of the G9a-10 complex, the first cocrystal structure of G9a with a small molecule inhibitor, was obtained. On the basis of the structural insights revealed by this cocrystal structure, optimization of the 7-dimethylaminopropoxy side chain of 10 resulted in the discovery of 29 (UNC0321) (Morrison K(i) = 63 pM), which is the first G9a inhibitor with picomolar potency and the most potent G9a inhibitor to date.
Project description:Lysyl oxidase (LOX) is a secreted copper-dependent amine oxidase that cross-links collagens and elastin in the extracellular matrix and is a critical mediator of tumor growth and metastatic spread. LOX is a target for cancer therapy, and thus the search for therapeutic agents against LOX has been widely sought. We report herein the medicinal chemistry discovery of a series of LOX inhibitors bearing an aminomethylenethiophene (AMT) scaffold. High-throughput screening provided the initial hits. Structure-activity relationship (SAR) studies led to the discovery of AMT inhibitors with sub-micromolar half-maximal inhibitory concentrations (IC50) in a LOX enzyme activity assay. Further SAR optimization yielded the orally bioavailable LOX inhibitor CCT365623 with good anti-LOX potency, selectivity, pharmacokinetic properties, as well as anti-metastatic efficacy.
Project description:In order to better understand the structure-activity relationship of mangostin, a series of xanthone derivatives based on α-mangostin were designed and synthesized. All the compounds were evaluated for their cytotoxicity against a panel of five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480) using MTT assays. Most of them showed cytotoxicity and most of all, compounds 1a and 2h showed the highest cytotoxic potency by HL-60 cancer cell lines with IC50 values of 5.96 μM and 6.90 μM respectively; compound 3e showed the highest cytotoxic potency against SMMC-7221 cancer cell line with IC50 values of 3.98 μM; compounds 2e and 2m showed lower cytotoxicity but higher selectivity than α-mangostin against HL-60 and SMMC-7221 cancer cell lines respectively. Structure-activity relationship analysis indicates that the maintenance of the isopentene group at C-8 is essential for the cytotoxic activity.
Project description:Autotaxin (ATX) is a secreted soluble enzyme that generates lysophosphatidic acid (LPA) through its lysophospholipase D activity. Because of LPA's role in neoplastic diseases, ATX is an attractive therapeutic target due to its involvement in LPA biosynthesis. Here we describe the SAR of ATX inhibitor, VPC8a202, and apply this SAR knowledge towards developing a high potency inhibitor. We found that electron density in the pyridine region greatly influences activity of our inhibitors at ATX.
Project description:Protein kinase D (PKD) is a member of a novel family of serine/threonine kinases that regulate fundamental cellular processes. PKD is implicated in the pathogenesis of several diseases, including cancer. Progress in understanding the biological functions and therapeutic potential of PKD has been hampered by the lack of specific inhibitors. The benzoxoloazepinolone CID755673 was recently identified as the first potent and selective PKD inhibitor. The study of structure-activity relationships (SAR) of this lead structure led to further improvements in PKD1 potency. We describe herein the synthesis and biological evaluation of novel benzothienothiazepinone analogs. We achieved a ten-fold increase in the in vitro PKD1 inhibitory potency for the second generation lead kb-NB142-70 and accomplished a transition to an almost equally potent novel pyrimidine scaffold, while maintaining excellent target selectivity. These promising results will guide the design of pharmacological tools to dissect PKD function and pave the way for the development of potential anti-cancer agents.
Project description:A new series of 3-ethynyl-1H-indazoles has been synthesized and evaluated in both biochemical and cell-based assays as potential kinase inhibitors. Interestingly, a selected group of compounds identified from this series exhibited low micromolar inhibition against critical components of the PI3K pathway, targeting PI3K, PDK1, and mTOR kinases. A combination of computational modeling and structure-activity relationship studies reveals a possible novel mode for PI3K inhibition, resulting in a PI3Kα isoform-specific compound. Hence, by targeting the most oncogenic mutant isoform of PI3K, the compound displays antiproliferative activity both in monolayer human cancer cell cultures and in three-dimensional tumor models. Because of its favorable physicochemical, in vitro ADME and drug-like properties, we propose that this novel ATP mimetic scaffold could prove useful in deriving novel selecting and multikinase inhibitors for clinical use.
Project description:Huntington's disease (HD) is a rare single-gene neurodegenerative disease, which can only be treated symptomatically. Currently, there are no approved drugs for HD on the market. Studies have found that MAPK11 can serve as a potential therapeutic target for HD. Regrettably, no MAPK11 small molecule inhibitors have been approved at present. This paper presents three series of compounds that were designed and synthesized based on the structure of skepinone-L, a known MAPK14 inhibitor. Among the synthesized compounds, 13a and 13b, with IC50 values of 6.40 nM and 4.20 nM, respectively, displayed the best inhibitory activities against MAPK11. Furthermore, the structure-activity relationship (SAR) is discussed in detail, which is constructive in optimizing the MAPK11 inhibitors for better activity and effect against HD.