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1.  Hydrocarbon-Stapled Peptides: Principles, Practice, and Progress 
Journal of Medicinal Chemistry  2014;57(15):6275-6288.
Protein structure underlies essential biological processes and provides a blueprint for molecular mimicry that drives drug discovery. Although small molecules represent the lion’s share of agents that target proteins for therapeutic benefit, there remains no substitute for the natural properties of proteins and their peptide subunits in the majority of biological contexts. The peptide α-helix represents a common structural motif that mediates communication between signaling proteins. Because peptides can lose their shape when taken out of context, developing chemical interventions to stabilize their bioactive structure remains an active area of research. The all-hydrocarbon staple has emerged as one such solution, conferring α-helical structure, protease resistance, cellular penetrance, and biological activity upon successful incorporation of a series of design and application principles. Here, we describe our more than decade-long experience in developing stapled peptides as biomedical research tools and prototype therapeutics, highlighting lessons learned, pitfalls to avoid, and keys to success.
PMCID: PMC4136684  PMID: 24601557
2.  The Current State of Drug Discovery and a Potential Role for NMR Metabolomics 
Journal of Medicinal Chemistry  2014;57(14):5860-5870.
The pharmaceutical industry has significantly contributed to improving human health. Drugs have been attributed to both increasing life expectancy and decreasing health care costs. Unfortunately, there has been a recent decline in the creativity and productivity of the pharmaceutical industry. This is a complex issue with many contributing factors resulting from the numerous mergers, increase in out-sourcing, and the heavy dependency on high-throughput screening (HTS). While a simple solution to such a complex problem is unrealistic and highly unlikely, the inclusion of metabolomics as a routine component of the drug discovery process may provide some solutions to these problems. Specifically, as the binding affinity of a chemical lead is evolved during the iterative structure-based drug design process, metabolomics can provide feedback on the selectivity and the in vivo mechanism of action. Similarly, metabolomics can be used to evaluate and validate HTS leads. In effect, metabolomics can be used to eliminate compounds with potential efficacy and side effect problems while prioritizing well-behaved leads with druglike characteristics.
PMCID: PMC4324437  PMID: 24588729
3.  Heat Shock Protein 70 Inhibitors. 2. 2,5′-Thiodipyrimidines, 5-(Phenylthio)pyrimidines, 2-(Pyridin-3-ylthio)pyrimidines, and 3-(Phenylthio)pyridines as Reversible Binders to an Allosteric Site on Heat Shock Protein 70 
Journal of Medicinal Chemistry  2014;57(4):1208-1224.
The discovery and development of heat shock protein 70 (Hsp70) inhibitors is currently a hot topic in cancer. In the preceding paper in this issue (10.1021/jm401551n), we have described structure–activity relationship studies in the first Hsp70 inhibitor class rationally designed to bind to a novel allosteric pocket located in the N-terminal domain of the protein. These ligands contained an acrylamide to take advantage of an active cysteine embedded in the allosteric pocket and acted as covalent protein modifiers upon binding. Here, we perform chemical modifications around the irreversible inhibitor scaffold to demonstrate that covalent modification is not a requirement for activity within this class of compounds. The study identifies derivative 27c, which mimics the biological effects of the irreversible inhibitors at comparable concentrations. Collectively, the back-to-back manuscripts describe the first pharmacophores that favorably and selectively interact with a never explored pocket in Hsp70 and provide a novel blueprint for a cancer-oriented development of Hsp70-directed ligands.
PMCID: PMC3983364  PMID: 24548239
4.  Heat Shock Protein 70 Inhibitors. 1. 2,5′-Thiodipyrimidine and 5-(Phenylthio)pyrimidine Acrylamides as Irreversible Binders to an Allosteric Site on Heat Shock Protein 70 
Journal of Medicinal Chemistry  2014;57(4):1188-1207.
Heat shock protein 70 (Hsp70) is an important emerging cancer target whose inhibition may affect multiple cancer-associated signaling pathways and, moreover, result in significant cancer cell apoptosis. Despite considerable interest from both academia and pharmaceutical companies in the discovery and development of druglike Hsp70 inhibitors, little success has been reported so far. Here we describe structure–activity relationship studies in the first rationally designed Hsp70 inhibitor class that binds to a novel allosteric pocket located in the N-terminal domain of the protein. These 2,5′-thiodipyrimidine and 5-(phenylthio)pyrimidine acrylamides take advantage of an active cysteine embedded in the allosteric pocket to act as covalent protein modifiers upon binding. The study identifies derivatives 17a and 20a, which selectively bind to Hsp70 in cancer cells. Addition of high nanomolar to low micromolar concentrations of these inhibitors to cancer cells leads to a reduction in the steady-state levels of Hsp70-sheltered oncoproteins, an effect associated with inhibition of cancer cell growth and apoptosis. In summary, the described scaffolds represent a viable starting point for the development of druglike Hsp70 inhibitors as novel anticancer therapeutics.
PMCID: PMC3983365  PMID: 24548207
5.  64Cu-Labeled Inhibitors of Prostate-Specific Membrane Antigen for PET Imaging of Prostate Cancer 
Journal of Medicinal Chemistry  2014;57(6):2657-2669.
Prostate-specific membrane antigen (PSMA) is a well-recognized target for identification and therapy of a variety of cancers. Here we report five 64Cu-labeled inhibitors of PSMA, [64Cu]3–7, which are based on the lysine–glutamate urea scaffold and utilize a variety of macrocyclic chelators, namely NOTA(3), PCTA(4), Oxo-DO3A(5), CB-TE2A(6), and DOTA(7), in an effort to determine which provides the most suitable pharmacokinetics for in vivo PET imaging. [64Cu]3–7 were prepared in high radiochemical yield (60–90%) and purity (>95%). Positron emission tomography (PET) imaging studies of [64Cu]3–7 revealed specific accumulation in PSMA-expressing xenografts (PSMA+ PC3 PIP) relative to isogenic control tumor (PSMA– PC3 flu) and background tissue. The favorable kinetics and high image contrast provided by CB-TE2A chelated [64Cu]6 suggest it as the most promising among the candidates tested. That could be due to the higher stability of [64Cu]CB-TE2A as compared with [64Cu]NOTA, [64Cu]PCTA, [64Cu]Oxo-DO3A, and [64Cu]DOTA chelates in vivo.
PMCID: PMC3983358  PMID: 24533799
6.  wALADin Benzimidazoles Differentially Modulate the Function of Porphobilinogen Synthase Orthologs 
Journal of Medicinal Chemistry  2014;57(6):2498-2510.
The heme biosynthesis enzyme porphobilinogen synthase (PBGS) is a potential drug target in several human pathogens. wALADin1 benzimidazoles have emerged as species-selective PBGS inhibitors against Wolbachia endobacteria of filarial worms. In the present study, we have systematically tested wALADins against PBGS orthologs from bacteria, protozoa, metazoa, and plants to elucidate the inhibitory spectrum. However, the effect of wALADin1 on different PBGS orthologs was not limited to inhibition: several orthologs were stimulated by wALADin1; others remained unaffected. We demonstrate that wALADins allosterically modulate the PBGS homooligomeric equilibrium with inhibition mediated by favoring low-activity oligomers, while 5-aminolevulinic acid, Mg2+, or K+ stabilized high-activity oligomers. Pseudomonas aeruginosa PBGS could be inhibited or stimulated by wALADin1 depending on these factors and pH. We have defined the wALADin chemotypes responsible for either inhibition or stimulation, facilitating the design of tailored PBGS modulators for potential application as antimicrobial agents, herbicides, or drugs for porphyric disorders.
PMCID: PMC3983392  PMID: 24568185
7.  Structure-Guided, Single-Point Modifications in the Phosphinic Dipeptide Structure Yield Highly Potent and Selective Inhibitors of Neutral Aminopeptidases 
Journal of Medicinal Chemistry  2014;57(19):8140-8151.
Seven crystal structures of alanyl aminopeptidase from Neisseria meningitides (the etiological agent of meningitis, NmAPN) complexed with organophosphorus compounds were resolved to determine the optimal inhibitor–enzyme interactions. The enantiomeric phosphonic acid analogs of Leu and hPhe, which correspond to the P1 amino acid residues of well-processed substrates, were used to assess the impact of the absolute configuration and the stereospecific hydrogen bond network formed between the aminophosphonate polar head and the active site residues on the binding affinity. For the hPhe analog, an imperfect stereochemical complementarity could be overcome by incorporating an appropriate P1 side chain. The constitution of P1′-extended structures was rationally designed and the lead, phosphinic dipeptide hPhePψ[CH2]Phe, was modified in a single position. Introducing a heteroatom/heteroatom-based fragment to either the P1 or P1′ residue required new synthetic pathways. The compounds in the refined structure were low nanomolar and subnanomolar inhibitors of N. meningitides, porcine and human APNs, and the reference leucine aminopeptidase (LAP). The unnatural phosphinic dipeptide analogs exhibited a high affinity for monozinc APNs associated with a reasonable selectivity versus dizinc LAP. Another set of crystal structures containing the NmAPN dipeptide ligand were used to verify and to confirm the predicted binding modes; furthermore, novel contacts, which were promising for inhibitor development, were identified, including a π–π stacking interaction between a pyridine ring and Tyr372.
PMCID: PMC4331105  PMID: 25192493
8.  Novel 2,4-Disubstituted Pyrimidines as Potent, Selective, and Cell-Permeable Inhibitors of Neuronal Nitric Oxide Synthase 
Journal of Medicinal Chemistry  2014;58(3):1067-1088.
Selective inhibition of neuronal nitric oxide synthase (nNOS) is an important therapeutic approach to target neurodegenerative disorders. However, the majority of the nNOS inhibitors developed are arginine mimetics and, therefore, suffer from poor bioavailability. We designed a novel strategy to combine a more pharmacokinetically favorable 2-imidazolylpyrimidine head with promising structural components from previous inhibitors. In conjunction with extensive structure–activity studies, several highly potent and selective inhibitors of nNOS were discovered. X-ray crystallographic analysis reveals that these type II inhibitors utilize the same hydrophobic pocket to gain strong inhibitory potency (13), as well as high isoform selectivity. Interestingly, select compounds from this series (9) showed good permeability and low efflux in a Caco-2 assay, suggesting potential oral bioavailability, and exhibited minimal off-target binding to 50 central nervous system receptors. Furthermore, even with heme-coordinating groups in the molecule, modifying other pharmacophoric fragments minimized undesirable inhibition of cytochrome P450s from human liver microsomes.
PMCID: PMC4329833  PMID: 25489882
9.  Design, Synthesis, and Characterization of α-Ketoheterocycles Additionally Targeting the Cytosolic Port Cys269 of Fatty Acid Amide Hydrolase 
Journal of medicinal chemistry  2014;57(3):1079-1089.
A series of α-ketooxazoles incorporating electrophiles at the C5 position of the pyridyl ring of 2 (OL-135) and related compounds were prepared and examined as inhibitors of fatty acid amide hydrolase (FAAH), additionally targeting the cytosolic port Cys269. From this series, a subset of the candidate inhibitors exhibited time-dependent FAAH inhibition and non-competitive irreversible inactivation of the enzyme, consistent with the targeted Cys269 covalent alkylation or addition, and maintained or enhanced the intrinsic selectivity for FAAH versus other serine hydrolases. A preliminary in vivo assessment demonstrates that these inhibitors raise endogenous brain levels of anandamide and other FAAH substrates upon intraperitoneal (i.p.) administration to mice with peak levels achieved within 1.5–3 h and that the elevations of the signaling lipids were maintained >6 h, indicating that the inhibitors effectively reach and remain active in the brain inhibiting FAAH for a sustained period.
PMCID: PMC3940414  PMID: 24456116
10.  Development of Selective Inhibitors for Aldehyde Dehydrogenases based on Substituted Indole-2,3-diones 
Journal of medicinal chemistry  2014;57(3):714-722.
Aldehyde dehydrogenases (ALDH) participate in multiple metabolic pathways and have been indicated to play a role in several cancerous disease states. Our laboratory is interested in developing novel and selective ALDH inhibitors. We looked to further work recently published by developing a class of isoenzyme selective inhibitors using a similar indole-2,3-diones that exhibit differential inhibition of ALDH1A1, ALDH2 and ALDH3A1. Kinetic and X-ray crystallography data suggest these inhibitors are competitive against aldehyde binding, forming direct interactions with active site cysteine residues. The selectivity is precise in that these compounds appear to interact directly with the catalytic nucleophile, Cys243, in ALDH3A1, but not in ALDH2. In ALDH2, the 3-keto group is surrounded by the adjacent Cys301/303. Surprisingly, the orientation of the interaction changes depending on the nature of the substitutions on the basic indole ring structure and correlates well with the observed structure-activity relationships for each ALDH isoenzyme.
PMCID: PMC3954746  PMID: 24444054
11.  Substituted 2-Phenyl-Imidazopyridines: A New Class of Drug Leads for Human African Trypanosomiasis 
Journal of medicinal chemistry  2014;57(3):828-835.
A phenotypic screen of a compound library for antiparasitic activity on Trypanosoma brucei, the causative agent of human African trypanosomiasis, led to the identification of substituted 2-(3-aminophenyl) oxazolopyridines as a starting point for hit-to-lead medicinal chemistry. A total of 110 analogues were prepared, which led to the identification of 64, a substituted 2-(3-aminophenyl) imidazopyridine. This compound showed antiparasitic activity in vitro with an EC50 of 2 nM and displayed reasonable drug-like properties when tested in a number of in vitro assays. The compound was orally bioavailable and displayed good plasma and brain exposure in mice. Compound 64 cured mice infected with Trypanosoma brucei when dosed orally down to 2.5 mg/kg. Given its potent anti-parasitic properties and its ease of synthesis, compound 64 represents a new lead for the development of drugs to treat human African trypanosomiasis.
PMCID: PMC3962778  PMID: 24354316
12.  Discovery of 8-Cyclopentyl-2-[4-(4-methyl-piperazin-1-yl)-phenylamino]-7-oxo-7,8- dihydro-pyrido[2,3-d]pyrimidine-6-carbonitrile (7x) as a Potent Inhibitor of Cyclin- Dependent Kinase 4 (CDK4) and AMPK-related Kinase 5 (ARK5) 
Journal of medicinal chemistry  2014;57(3):578-599.
The success of imatinib, a BCR-ABL inhibitor for the treatment of chronic myelogenous leukemia, has created a great impetus for the development of additional kinase inhibitors as therapeutic agents. However, the complexity of cancer has led to recent interest in polypharmacological approaches for developing multi kinase inhibitors with low toxicity profiles. With this goal in mind, we analyzed more than 150 novel cyano pyridopyrimidine compounds and identified structure activity relationship trends that can be exploited in the design of potent kinase inhibitors. One compound, 8-Cyclopentyl-2-[4-(4-methyl-piperazin-1-yl)-phenylamino]-7-oxo-7,8-dihydro-pyrido[2,3-d]pyrimidine-6-carbonitrile (7x) was found to be the most active, inducing apoptosis of tumor cells at a concentration of approximately 30–100nM. In vitro kinase profiling revealed that 7x is a multi-kinase inhibitor with potent inhibitory activity against the CDK4/CYCLIN D1 and ARK5 kinases. Here, we report the synthesis, structure activity relationship, kinase inhibitory profile, in vitro cytotoxicity and in vivo tumor regression studies by this lead compound.
PMCID: PMC3983396  PMID: 24417566
13.  Nitric Oxide (NO) Releasing Poly ADP-ribose Polymerase 1 (PARP-1) Inhibitors Targeted to Glutathione S-Transferase P1-Overexpressing Cancer Cells 
Journal of Medicinal Chemistry  2014;57(6):2292-2302.
We report the antitumor effects of nitric oxide (NO) releasing derivatives of the PARP-1 inhibitor olaparib (1). Compound 5b was prepared by coupling the carboxyl group of 3b and the free amino group of arylated diazeniumdiolated piperazine 4. Analogue 5a has the same structure except that the F is replaced by H. Compound 13 is the same as 5b except that a Me2N–N(O)=NO– group was added para and ortho to the nitro groups of the dinitrophenyl ring. The resulting prodrugs are activated by glutathione in a reaction accelerated by glutathione S-transferase P1 (GSTP1), an enzyme frequently overexpressed in cancers. This metabolism generates NO plus a PARP-1 inhibitor simultaneously, consuming reducing equivalents, leading to DNA damage concomitant with inhibition of DNA repair, and in the case of 13 inducing cross-linking glutathionylation of proteins. Compounds 5b and 13 reduced the growth rates of A549 human lung adenocarcinoma xenografts with no evidence of systemic toxicity.
PMCID: PMC3983374  PMID: 24521039
14.  Synthesis and Biological Evaluation of New Carbohydrate-Substituted Indenoisoquinoline Topoisomerase I Inhibitors and Improved Syntheses of the Experimental Anticancer Agents Indotecan (LMP400) and Indimitecan (LMP776) 
Journal of Medicinal Chemistry  2014;57(4):1495-1512.
Carbohydrate moieties were strategically transported from the indolocarbazole topoisomerase I (Top1) inhibitor class to the indenoisoquinoline system in search of structurally novel and potent Top1 inhibitors. The syntheses and biological evaluation of 20 new indenoisoquinolines glycosylated with linear and cyclic sugar moieties are reported. Aromatic ring substitution with 2,3-dimethoxy-8,9-methylenedioxy or 3-nitro groups exerted strong effects on antiproliferative and Top1 inhibitory activities. While the length of the carbohydrate side chain clearly correlated with antiproliferative activity, the relationship between stereochemistry and biological activity was less clearly defined. Twelve of the new indenoisoquinolines exhibit Top1 inhibitory activity equal to or better than that of camptothecin. An advanced synthetic intermediate from this study was also used to efficiently prepare indotecan (LMP400) and indimitecan (LMP776), two anticancer agents currently under investigation in a Phase I clinical trial at the National Institutes of Health.
PMCID: PMC3983348  PMID: 24517248
15.  Identification of Tetrapeptides from a Mixture Based Positional Scanning Library That Can Restore nM Full Agonist Function of the L106P, I69T, I102S, A219V, C271Y, and C271R Human Melanocortin-4 Polymorphic Receptors (hMC4Rs) 
Journal of Medicinal Chemistry  2014;57(11):4615-4628.
Human obesity has been linked to genetic factors and single nucleotide polymorphisms (SNPs). Melanocortin-4 receptor (MC4R) SNPs have been associated with up to 6% frequency in morbidly obese children and adults. A potential therapy for individuals possessing such genetic modifications is the identification of molecules that can restore proper receptor signaling and function. These compounds could serve as personalized medications improving quality of life issues as well as alleviating diseases symptoms associated with obesity including type 2 diabetes. Several hMC4 SNP receptors have been pharmacologically characterized in vitro to have a decreased, or a lack of response, to endogenous agonists such as α-, β-, and γ2-melanocyte stimulating hormones (MSH) and adrenocorticotropin hormone (ACTH). Herein we report the use of a mixture based positional scanning combinatorial tetrapeptide library to discover molecules with nM full agonist potency and efficacy to the L106P, I69T, I102S, A219V, C271Y, and C271R hMC4Rs. The most potent compounds at all these hMC4R SNPs include Ac-His-(pI)DPhe-Tic-(pNO2)DPhe-NH2, Ac-His-(pCl)DPhe-Tic-(pNO2)DPhe-NH2, Ac-His-(pCl)DPhe-Arg-(pI)Phe-NH2, and Ac-Arg-(pCl)DPhe-Tic-(pNO2)DPhe-NH2, revealing new ligand pharmacophore models for melanocortin receptor drug design strategies.
PMCID: PMC4324447  PMID: 24517312
16.  Design, Synthesis, and Structure–Activity Relationship of a Novel Series of GluN2C-Selective Potentiators 
Journal of Medicinal Chemistry  2014;57(6):2334-2356.
NMDA receptors are tetrameric complexes composed of GluN1 and GluN2A–D subunits that mediate a slow Ca2+-permeable component of excitatory synaptic transmission. NMDA receptors have been implicated in a wide range of neurological diseases and thus represent an important therapeutic target. We herein describe a novel series of pyrrolidinones that selectively potentiate only NMDA receptors that contain the GluN2C subunit. The most active analogues tested were over 100-fold selective for recombinant GluN2C-containing receptors over GluN2A/B/D-containing NMDA receptors as well as AMPA and kainate receptors. This series represents the first class of allosteric potentiators that are selective for diheteromeric GluN2C-containing NMDA receptors.
PMCID: PMC3983368  PMID: 24512267
17.  Optimization of the Lactam Side Chain of 7-Azaindenoisoquinoline Topoisomerase I Inhibitors and Mechanism of Action Studies in Cancer Cells 
Journal of Medicinal Chemistry  2014;57(4):1289-1298.
Optimization of the lactam ω-aminoalkyl substituents in a series of 7-azaindenoisoquinolines resulted in new anticancer agents with improved Top1 inhibitory potencies and cancer cell cytotoxicities. The new compounds 14–17 and 19 exhibited mean graph midpoint cytotoxicity (GI50) values of 21–71 nM in the NCI panel of 60 human cancer cell cultures. Ternary 7-azaindenoisoquinoline–DNA–Top1 cleavage complexes that persist for up to 6 h were detected in HCT116 colon cancer cells. Ternary complexes containing 7-azaindenoisoquinolines were significantly more stable than those in which camptothecin was incorporated. DNA content distribution histograms showed S-phase block 3 h after drug removal. Drug-induced DNA damage in HCT116 cells was revealed by induction of the histone γ-H2AX marker. The 7-azaindenoisoquinolines were able to partially overcome resistance in several drug-resistant cell lines, and they were not substrates for the ABCB1 drug efflux transporter. Molecular modeling studies indicate that the 7-azaindenoisoquinolines intercalate at the DNA cleavage site in DNA–Top1 covalent complexes with the lactam side chain projecting into the major groove. Overall, the results indicate that the 7-azaindenoisoquinolines are promising anticancer agents that merit further development.
PMCID: PMC3983387  PMID: 24502276
18.  Optimization of 4-(N-Cycloamino)phenylquinazolines as a Novel Class of Tubulin-Polymerization Inhibitors Targeting the Colchicine Site 
Journal of Medicinal Chemistry  2014;57(4):1390-1402.
The 6-methoxy-1,2,3,4-tetrahydroquinoline moiety in prior leads 2-chloro- and 2-methyl-4-(6-methoxy-3,4-dihydroquinolin-1(2H)-yl)quinazoline (1a and 1b) was modified to produce 4-(N-cycloamino)quinazolines (4a–c and 5a–m). The new compounds were evaluated in cytotoxicity and tubulin inhibition assays, resulting in the discovery of new tubulin-polymerization inhibitors. 7-Methoxy-4-(2-methylquinazolin-4-yl)-3,4-dihydroquinoxalin- 2(1H)-one (5f), the most potent compound, exhibited high in vitro cytotoxic activity (GI50 1.9–3.2 nM), significant potency against tubulin assembly (IC50 0.77 μM), and substantial inhibition of colchicine binding (99% at 5 μM). In mechanism studies, 5f caused cell arrest in G2/M phase, disrupted microtubule formation, and competed mostly at the colchicine site on tubulin. Compound 5f and N-methylated analogue 5g were evaluated in nude mouse MCF7 xenograft models to validate their antitumor activity. Compound 5g displayed significant in vivo activity (tumor inhibitory rate 51%) at a dose of 4 mg/kg without obvious toxicity, whereas 5f unexpectedly resulted in toxicity and death at the same dose.
PMCID: PMC3983391  PMID: 24502232
19.  Exploiting an Allosteric Binding Site of PRMT3 Yields Potent and Selective Inhibitors 
Journal of medicinal chemistry  2013;56(5):2110-2124.
Protein arginine methyltransferases (PRMTs) play an important role in diverse biological processes. Among the nine known human PRMTs, PRMT3 has been implicated in ribosomal biosynthesis via asymmetric dimethylation of the 40S ribosomal protein S2 and in cancer via interaction with the DAL-1 tumor suppressor protein. However, few selective inhibitors of PRMTs have been discovered. We recently disclosed the first selective PRMT3 inhibitor, which occupies a novel allosteric binding site and is noncompetitive with both the peptide substrate and cofactor. Here we report comprehensive structure–activity relationship studies of this series, which resulted in the discovery of multiple PRMT3 inhibitors with submicromolar potencies. An X-ray crystal structure of compound 14u in complex with PRMT3 confirmed that this inhibitor occupied the same allosteric binding site as our initial lead compound. These studies provide the first experimental evidence that potent and selective inhibitors can be created by exploiting the allosteric binding site of PRMT3.
PMCID: PMC4319713  PMID: 23445220
20.  [No title available] 
PMCID: PMC3954497  PMID: 24494745
21.  [No title available] 
PMCID: PMC3969094  PMID: 24491171
22.  [No title available] 
PMCID: PMC3983360  PMID: 24491146
23.  High-Affinity Small-Molecule Inhibitors of the Menin-Mixed Lineage Leukemia (MLL) Interaction Closely Mimic a Natural Protein–Protein Interaction 
Journal of Medicinal Chemistry  2014;57(4):1543-1556.
The protein–protein interaction (PPI) between menin and mixed lineage leukemia (MLL) plays a critical role in acute leukemias, and inhibition of this interaction represents a new potential therapeutic strategy for MLL leukemias. We report development of a novel class of small-molecule inhibitors of the menin–MLL interaction, the hydroxy- and aminomethylpiperidine compounds, which originated from HTS of ∼288000 small molecules. We determined menin–inhibitor co-crystal structures and found that these compounds closely mimic all key interactions of MLL with menin. Extensive crystallography studies combined with structure-based design were applied for optimization of these compounds, resulting in MIV-6R, which inhibits the menin–MLL interaction with IC50 = 56 nM. Treatment with MIV-6 demonstrated strong and selective effects in MLL leukemia cells, validating specific mechanism of action. Our studies provide novel and attractive scaffold as a new potential therapeutic approach for MLL leukemias and demonstrate an example of PPI amenable to inhibition by small molecules.
PMCID: PMC3983337  PMID: 24472025
24.  A Simple Litmus Test for Aldehyde Oxidase Metabolism of Heteroarenes 
Journal of Medicinal Chemistry  2014;57(4):1616-1620.
The bioavailability of aromatic azaheterocyclic drugs can be affected by the activity of aldehyde oxidase (AO). Susceptibility to AO metabolism is difficult to predict computationally and can be complicated in vivo by differences between species. Here we report the use of bis(((difluoromethyl)sulfinyl)oxy)zinc (DFMS) as a source of CF2H radical for a rapid and inexpensive chemical “litmus test” for the early identification of heteroaromatic drug candidates that have a high probability of metabolism by AO.
PMCID: PMC3983350  PMID: 24472070
25.  Bicyclic 1-Hydroxy-2-oxo-1,2-dihydropyridine-3-carboxamide-Containing HIV-1 Integrase Inhibitors Having High Antiviral Potency against Cells Harboring Raltegravir-Resistant Integrase Mutants 
Journal of Medicinal Chemistry  2014;57(4):1573-1582.
Integrase (IN) inhibitors are the newest class of antiretroviral agents developed for the treatment of HIV-1 infections. Merck’s Raltegravir (RAL) (October 2007) and Gilead’s Elvitegravir (EVG) (August 2012), which act as IN strand transfer inhibitors (INSTIs), were the first anti-IN drugs to be approved by the FDA. However, the virus develops resistance to both RAL and EVG, and there is extensive cross-resistance to these two drugs. New “2nd-generation” INSTIs are needed that will have greater efficacy against RAL- and EVG-resistant strains of IN. The FDA has recently approved the first second generation INSTI, GSK’s Dolutegravir (DTG) (August 2013). Our current article describes the design, synthesis, and evaluation of a series of 1,8-dihydroxy-2-oxo-1,2-dihydroquinoline-3-carboxamides, 1,4-dihydroxy-2-oxo-1,2-dihydro-1,8-naphthyridine-3-carboxamides, and 1-hydroxy-2-oxo-1,2-dihydro-1,8-naphthyridine-3-carboxamides. This resulted in the identification of noncytotoxic inhibitors that exhibited single digit nanomolar EC50 values against HIV-1 vectors harboring wild-type IN in cell-based assays. Importantly, some of these new inhibitors retain greater antiviral efficacy compared to that of RAL when tested against a panel of IN mutants that included Y143R, N155H, G140S/Q148H, G118R, and E138K/Q148K.
PMCID: PMC3983366  PMID: 24471816

Results 1-25 (1545)