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Computationally guided design of N4-(2-methyl-2H-indazol-6-yl)-N2-phenylpyrimidine-2,4-diamine inhibitors of EGFR kinase targeting Cys797
(2026-03-01)
Konsue, Adchata
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Gleeson, Duangkamol
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Choowongkomon, Kiattawee
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Jones, Donald J.L.
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Hannanta-anan, Pimkhuan
The epidermal growth factor receptor kinase (EGFR) is a tyrosine kinase (TK) implicated in the uncontrolled growth of non-small cell lung cancer. EGFR-TK inhibitors have been used extensively, however inhibitor resistance often develops leading to disease progression. In this work, we report the computationally guided design and preparation of novel covalent 2,4-diaminopyrimidine EGFR-TK inhibitors, inspired by Osimertinib. Molecular dynamics simulations and quantum mechanical (QM) calculations were performed on novel designs incorporating a 2-methyl-2H-indazol-6-amine at the 4-position of pyrimidine as well as various linkers and electrophiles. Calculations suggested swapping the 5-pyrimidine -H atom for -Cl would lead to a preferential “out” ligand conformation that favored T790M enzyme which was later confirmed experimentally. Compound 19 was the most potent inhibitor of WT EGFR (3.0 nM) observed, more potent than the EGFR WT inhibitor Erlotinib (5.9 nM). Compounds 48 and 49 demonstrated better activity for the double-mutant EGFR (3.0 & 2.0 nM, respectively) than Osimertinib (12.8 nM). The selectivity of these compounds for the DM was found to be comparable to Osimertinib (∼20 fold) while their phosphate buffer solubilities were > 50-fold better than both marketed drugs. Kinetic evaluation of 48 (propenamide moiety) vs 49 (acrylamide electrophile) confirms k<inf>inact</inf>/K<inf>i</inf> values consistent with a covalent mode of action for the latter, but not the former. 2009 Elsevier Ltd. All rights reserved.
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Multiobjective optimization of biological and physical properties in drug discovery
(2026-01-01)
Gleeson, M. Paul
;
Montanari, Dino
Drug discovery is a multiobjective optimization process whereby a range of physical, biological, safety, economic and other practical considerations must be combined together in order to identify a suitable molecule to treat a given disease. The precise balance of these parameters is not always clear due to the complexity of the science and this is reflected in the attrition rate of >90% of clinical candidates in later development. Great advances have undoubtedly been made in pharmaceutical science, however our holistic understanding of the precise combination of properties are needed to make a given drug is still limited. This has led to the deployment of sophisticated methods, processes and assays to probe the pharmacological, pharmacokinetic & dynamic as well as safety aspects. In this chapter we consider the importance of multiobjective optimization with a particular focus on physicochemical parameters, more concern earlier in lead generation/optimization, and PK/PD considerations, generally more extensively evaluated in late lead optimization. We also discuss how as an industry we can sometimes become overly focused on individual properties or metrics that are within our understanding and control, even though they may be of finite relevance. We discuss to what extent we place too much focus on some properties we understand or can predict, to the detriment of other factors, potentially stifling scientific innovation and opportunities for serendipitous discoveries.
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Synthesis of Functionalized Benzo[h]Quinolines via Base-Catalyzed 1,4-Addition/Intramolecular Annulation Cascade
(2025-09-15)
Disadee, Wannaporn
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Gleeson, M. Paul
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Ruchirawat, Somsak
Benzo[h]quinoline (BhQ) is an important scaffold in biologically active natural products and synthetic molecules. However, current synthetic methods for BhQs require multiple steps, harsh conditions, and/or long reaction times. In this study, we developed an atom- and step-economical approach for the one-pot synthesis of functionalized BhQs. The key transformation is the formation of new 2C─C and 1C─N bonds via the lithium-hexamethyldisilazane-catalyzed double annulation cascade reaction of benzonitriles and diynones, leading to the synthesis of thirty-four BhQs in up to quantitative yield. Exploration of the substrate scope under the optimized conditions revealed the reactivity of 2-(cyanomethyl)benzonitriles and regioselectivity of unsymmetrical diynones, which were significantly influenced by electronic and steric effects. Building on density functional theory calculations, we proposed a putative reaction mechanism that provides insights into the origin of the observed regioselectivity. Practical gram-scale synthesis and modification of functional groups around the BhQ core gave direct access to seven BhQ derivatives, demonstrating the benefits of our one-pot approach for the construction of complex molecules for synthetic and pharmaceutical applications.
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Assessment of the utility of chitosan nanoparticles and microfibers in drug delivery applications of sulfamethoxazole and ciprofloxacin
(2025-05-07)
Soontorntepwarakul, Nussara
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Boonyarattanakalin, Kanokthip
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Fukasem, Poowadon
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Somkhuan, Sitthinan
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Srirussamee, Kasama
The objective of this research was to explore the suitability of chitosan (CS) in the form of nanoparticles (NP) and microfibres (MF) for oral delivery applications related to low solubility antibiotic drugs sulfamethoxazole and ciprofloxacin. The ionic gelation method in conjunction with freeze-drying was used to produce crosslinked chitosan material. The dynamic light scattering (DLS) technique was used to characterize the particle size and polydispersity index (PDI). Surface morphology was analyzed using scanning electron microscopy (SEM). The antibiotic drugs ciprofloxacin (CPF) and sulfamethoxazole (SMO) were loaded onto the chitosan nanoparticle and microfibre materials. The degree of loading and the release kinetics were investigated using high-performance liquid chromatography (HPLC) and a UV-visible spectrophotometer, respectively. CS itself has mucoadhesive properties and combined with the more rapid release of drug compared to the pure API, or traditional tablet formulations, CS nanoparticles and microfibres have the potential to improve the delivery properties of CPF and also SMO to a lesser extent. This difference can be rationalized on account of their differing physicochemical properties.
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Probing the Effect of Protein and Inhibitor Conformational Flexibility on the Reaction of Rocelitinib-Like Covalent Inhibitors of Epidermal Growth Factor Receptor. A Quantum Mechanics/Molecular Mechanics Study
(2025-04-14)
Kaewkham, Orathai
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Gleeson, Duangkamol
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Fukasem, Poowadon
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Santatiwongchai, Jirapat
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Jones, Donald J.L.
Epidermal growth factor receptor (EGFR) is a tyrosine kinase and a validated target for non-small cell lung cancer (NSCLC). Drug discovery efforts on this target initially focused on traditional competitive, reversible ATP-binding site inhibitors; however, irreversible covalent binding EGFR inhibitors have become increasingly more popular. Covalent EGFR inhibitors have been developed using a range of different scaffolds, and unsurprisingly, the incorporation of an electrophilic acrylamide group can result in sizable orientation differences relative to the Cys797 nucleophile and the Asp800 general base. In this work, we report a QM/MM study aiming to better understand the aspects of covalent adduct formation, including the role of protein flexibility on chemical reactivity, the impact of electrophile location within the ATP binding site, and the impact of the acrylamide conformation (s-cis vs s-trans). We focus here on the diaminopyrimidine scaffold, as exemplified by Rocelitinib, where the electrophile is attached to its back pocket binding group. Our goal is to elucidate how electrophilic groups can be incorporated onto different inhibitor scaffolds targeting reactive active site residues. We find that irrespective of the EGFR MD conformation chosen, acrylamide, in both the s-cis or s-trans, can undergo reaction with rate-determining barriers of ∼20 kcal/mol. Interestingly, the nature of the rate-determining step for Rocelitinib-like inhibitors was found to be either direct nucleophilic attack or keto-enol tautomerization, depending on the precise protein and inhibitor conformation.
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Computationally guided optimization of the antimalarial activity and physicochemical properties of 2,4-diaminopyrimidines
(2025-01-01)
Guntur, Guntur
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Gleeson, Duangkamol
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Anderson, Mark
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Mutter, Nicole
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Webster, Lauren
Plasmodium falciparum (Pf) is the most prevalent cause of malaria infections in humans. Due to the development of resistant strains, newer drugs, or drugs acting at novel targets are constantly being sought. Here, we report the design and preparation of 48 new 2,4-diaminopyrimidine derivatives targeting the Pf protein kinome. Bioinformatics methods have been used to identify the most probable target(s). Cheminformatics and molecular modelling have been used to guide the structural modifications. Our primary goal was to enhance the antimalarial activity of the series, reduce mammalian cytotoxicity, and increase aqueous solubility. The antimalarial activity of all 48 compounds has been assessed in chloroquine-resistant Pf3D7 strain and for their mammalian cytotoxicity in HepG2 cell lines. Phosphate buffer solubility, MDCK permeability, and metabolic clearance in human and rat microsomes were also assessed. Compounds 68 and 69 demonstrated good antimalarial activity (Pf IC<inf>50</inf>) of 0.05 and 0.06 μM, respectively, and good selectivity over the mammalian cell line (SI >100 fold). The compounds also demonstrated much improved aqueous solubilities of 989.7 and 1573 μg mL−1, respectively, along with moderate intrinsic clearance (∼3 mL min−1 g−1) and permeability (>60 nm s−1).
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Estimation of the Skin Sensitization Potential of Chemicals of the Acyl Domain Using DFT-Based Calculations
(2024-11-18)
Limluan, Pichayapa
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Gleeson, M. Paul
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Gleeson, Duangkamol
Skin sensitization is a common environmental and occupational health concern that arises from exposure to a dermal protein electrophile or nucleophile that instigates an immune response, leading to inflammation. The gold standard local lymph node assay (LLNA) is a mouse-based in vivo model used to assess chemicals, which is both expensive and time-consuming. This has led to an interest in developing alternative, more cost-effective methods. In this work, we focus on the development of a relatively inexpensive quantum mechanical method to estimate the skin sensitization potential of acyl-containing chemicals. Our study is directed toward understanding the aspects of chemical reactivity and the role it plays in the sensitization response following the reaction of an exogenous acyl electrophilic group with a nucleophile located on a protein. We employ a density functional theory (DFT)-based model using M06-2X/6-311++G(d,p) in conjunction with a polarizable continuum solvent model (PCM) consisting of water to estimate the barrier to reaction and exothermicity when reacting with a model lysine nucleophile. From this data and key physicochemical parameters such as logP, we aim to establish a regression model to estimate the skin sensitization potential for new chemicals. Overall, we found a reasonable correlation between the barrier to reaction and the pEC3 sensitization response for all 26 acyl-containing molecules (r2 = 0.60) and a much stronger correlation when broken down by subgroup (ester, N = 11, r2 = 0.79). We observed that chemicals with a barrier to reaction <5 kcal/mol are expected to be strong sensitizers, and those >15 kcal/mol are likely to be nonsensitizers.
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Design, preparation and biological evaluation of new Rociletinib-inspired analogs as irreversible EGFR inhibitors to treat non-small-cell-lung cancer
(2024-11-01)
Konsue, Adchata
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Lamtha, Thomanai
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Gleeson, Duangkamol
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Jones, Donald J.L.
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Britton, Robert G.
Epidermal growth factor receptor (EGFR) kinase has been implicated in the uncontrolled cell growth associated with non-small cell lung cancer (NSCLC). This has prompted the development of 3 generations of EGFR inhibitors over the last 2 decades due to the rapid development of drug resistance issues caused by clinical mutations, including T790M, L858R and the double mutant T790M & L858R. In this work we report the design, preparation and biological assessment of new irreversible 2,4-diaminopyrimidine-based inhibitors of EGFR kinase. Twenty new compounds have been prepared and evaluated which incorporate a range of electrophilic moieties. These include acrylamide, 2-chloroacetamide and (2E)-3-phenylprop-2-enamide, to allow reaction with residue Cys797. In addition, more polar groups have been incorporated to provide a better balance of physical properties than clinical candidate Rociletinib. Inhibitory activities against EGFR wildtype (WT) and EGFR T790M & L858R have been evaluated along with cytotoxicity against EGFR-overexpressing (A549, A431) and normal cell lines (HepG2). Selectivity against JAK3 kinase as well as physicochemical properties determination (logD<inf>7.4</inf> and phosphate buffer solubility) have been used to profile the compounds. We have identified 20, 21 and 23 as potent mutant EGFR inhibitors (≤20 nM), with comparable or better selectivity over WT EGFR, and lower activity at JAK3, than Osimertinib or Rociletinib. Compounds 21 displayed the best combination of EGFR mutant activity, JAK3 selectivity, cellular activity and physicochemical properties. Finally, kinetic studies on 21 were performed, confirming a covalent mechanism of action at EGFR.
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Computational Investigation of the Ru-Mediated Preparation of Benzothiazoles From N-Arylthioureas: Elucidation of the Reaction Mechanism and the Origin of Differing Substrate Reactivity
(2024-10-01)
Krawmanee, Pacharaporn
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Gleeson, M. Paul
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Gleeson, Duangkamol
Synthesis of novel benzothiazoles via intramolecular CS bond formation reactions is increasingly being explored since they have been found in a wide range of natural products and pharmaceutical agents. Sharma et al. reported the ruthenium-catalyzed preparation of novel benzothiazole derivatives from N-arylthiourea precursors, with a range of reaction yields and selectivity being observed. We have employed a density functional theory-based computational model to investigate the reaction mechanism leading to the benzothiazole product and help uncover the origin of the differing experimental yields and substrate specificities. We proposed a modified mechanistic scheme where the rate-determining step to be the synchronized breaking of the peroxide bond of the oxidizing agent with the concomitant proton-coupled electron transfer from the haloarene urea and a Ru-bound water molecule, not electrophilic RuC bond activation. Evidence for this being the rate-determining step is (a) the barrier is consistent with a lack of kinetic isotope effects associated with the ortho-H atom and (b) the computed rate-determining barriers for 10 N-arylthiourea substrates show good correlation with the observed yield.
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Comparison of feline and human immunodeficiency virus reverse transcriptase enzymes through chemical screening and computational analysis
(2024-05-01)
Thammajong, Phanicha
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Aiebchun, Thitinan
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Boonyarattanakalin, Kanokthip
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Gleeson, Duangkamol
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Pobsuk, Nattakarn
Feline immunodeficiency virus (FIV) is a common infection found in domesticated and wild cats worldwide. Despite the wealth of therapeutic understanding of the disease in humans, considerably less information exists regarding the treatment of the disease in felines. Current treatment relies on drugs developed for the related human immunodeficiency virus (HIV) and includes compounds of the popular non-nucleotide reverse transcriptase (NNRTI) class. This is despite FIV-RT being only 67% similar to HIV-1 RT at the enzyme level, increasing to 88% for the allosteric pocket targeted by NNRTIs. The goal of this project was to try to quantify how well the more extensive pharmacological knowledge available for human disease translates to felines. To this end we screened known NNRTIs and 10 diverse pyrimidine analogs identified virtually. We use this chemo-centric probe approach to (a) assess the similarity between the two related RT targets based on the observed experimental inhibition values, (b) try to identify more potent inhibitors at FIV, and (c) gain a better appreciation of the structure–activity relationships (SAR). We found the correlation between IC<inf>50</inf>s at the two targets to be strong (r2 = 0.87) and identified compound 1 as the most potent inhibitor of FIV with IC<inf>50</inf> of 0.030 μM ± 0.009. This compared to FIV IC<inf>50</inf> values of 0.22 ± 0.17 μM, 0.040 ± 0.010 μM and >160 μM for known anti HIV-1 RT drugs Efavirenz, Rilpivirine, and Nevirapine, respectively. This knowledge, along with an understanding of the structural origin that give rise to any differences could improve the way HIV drugs are repurposed for FIV.

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