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Repurposing PARP-1 inhibitors (PARPi) for non-oncological applications offers an attractive therapeutic strategy for pathological conditions characterized by PARP-1 hyperactivity. In the context of Parkinson's disease (PD), PARP-1 hyperactivity has been linked to neuronal death and disease progression. From a therapy perspective, the evaluation of PARPi as neuroprotective agents may offer a new therapeutic alternative for neurodegenerative disorders. An ideal PARPi needs to inhibit PARP-1 hyperactivity while also limiting downstream DNA damage and cellular toxicity-an effect that is attractive in cancer but far from ideal in neurological disease applications. Consequently, in this study, we set out to evaluate the neuroprotective properties of a previously reported low-toxicity PARPi (10e) using in vitro neuronal models of PD. 10e is a structural analogue of FDA-approved PARPi olaparib, with high PARP-1 affinity and selectivity. Our studies revealed that 10e protects neuronal cells from oxidative stress and DNA damage. In addition, 10e exhibits neuroprotective properties against α-synuclein pre-formed fibrils (αSyn PFF) mediated effects, including reduction in the levels of phosphorylated αSyn and protection against abnormal changes in NAD + levels. Our in vitro studies with 10e provide support for repurposing high-affinity and low-toxicity PARPi for neurological applications and lay the groundwork for long-term therapeutic studies in animal models of PD., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

A facile one-pot strategy for 13 CN and 14 CN exchange with aryl, heteroaryl, and alkenyl nitriles using a Ni phosphine catalyst and BPh 3 is described. This late-stage carbon isotope exchange (CIE) strategy employs labeled Zn(CN) 2 to facilitate enrichment using the nonlabeled parent compound as the starting material, eliminating de novo synthesis for precursor development. A broad substrate scope encompassing multiple pharmaceuticals is disclosed, including the preparation of [ 14 C] belzutifan to illustrate the exceptional functional group tolerance and utility of this labeling approach. Preliminary experimental and computational studies suggest the Lewis acid BPh 3 is not critical for the oxidative addition step and instead plays a role in facilitating CN exchange on Ni. This CIE method dramatically reduces the synthetic steps and radioactive waste involved in preparation of 14 C labeled tracers for clinical development.

Cell-cell interactions and communication are crucial to the proper function of complex mammalian physiology including neurocognitive and immune system functions. While many tools are available for observing and perturbing intracellular processes, relatively few exist to probe intercellular processes. Current techniques for studying interactions often rely on direct protein contact, and few can manipulate diverse, functional outputs with tunable protein expression. To address these limitations, we have developed a small-molecule approach based on a trimethoprim prodrug-enzyme pair capable of reporting the presence of two different engineered cell populations with programmable protein outputs. The approach relies on bacterial nitroreductase enzyme catalysis, which is orthogonal to normal mammalian biology, and diffusion of trimethoprim from "activator" cells to "receiver" cells. We test this strategy, which can theoretically regulate many different types of proteins, using biochemical and in vitro culture assays with optical and cytokine protein readouts. This describes the first small-molecule approach capable of detecting and controlling engineered cell-cell outputs, and we anticipate future applications that are especially relevant to the field of immuno-oncology.

A solid understanding of the mechanisms governing ligand binding is crucial for rational design of therapeutics targeting the dopamine D 2 receptor (D 2 R). Here, we use G protein-coupled inward rectifier potassium (GIRK) channel activation in Xenopus oocytes to measure the kinetics of D 2 R antagonism by a series of aripiprazole analogues, as well as the recovery of dopamine (DA) responsivity upon washout. The aripiprazole analogues comprise an orthosteric and a secondary pharmacophore and differ by the length of the saturated carbon linker joining these two pharmacophores. Two compounds containing 3- and 5-carbon linkers allowed for a similar extent of recovery from antagonism in the presence of 1 or 100 μM DA (>25 and >90% of control, respectively), whereas recovery was less prominent (∼20%) upon washout of the 4-carbon linker compound, SV-III-130, both with 1 and 100 μM DA. Prolonging the coincubation time with SV-III-130 further diminished recovery. Curve-shift experiments were consistent with competition between SV-III-130 and DA. Two mutations in the secondary binding pocket (V91A and E95A) of D 2 R decreased antagonistic potency and increased recovery from SV-III-130 antagonism, whereas a third mutation (L94A) only increased recovery. Our results suggest that the secondary binding pocket influences recovery from inhibition by the studied aripiprazole analogues. We propose a mechanism, supported by in silico modeling, whereby SV-III-130 initially binds reversibly to the D 2 R, after which the drug-receptor complex undergoes a slow transition to a second ligand-bound state, which is dependent on secondary binding pocket integrity and irreversible during the time frame of our experiments.

A late-stage 18 O labeling approach of sulfonamides that employs the corresponding unlabeled molecule as the starting material was developed. Upon deamination of the sulfonamide, a sulfinate intermediate was isotopically enriched using eco-friendly reagents H 2 18 O and 15 NH 3 (aq) to afford a M+5 isotopologue of the parent compound. This degradation-reconstruction approach afforded isolated yields of up to 96 % for the stable isotope labeled (SIL) sulfonamides, and was compatible with multiple marketed therapeutics, including celecoxib, on a gram scale. The SIL products also exhibited no 18 O/ 16 O back exchange under extreme conditions, further validating the utility of this green strategy for drug labeling for both in vitro and in vivo use. This procedure was also adapted to include pharmaceutically relevant methyl sulfones by using 13 CH 3 , affording M+5 isotopic enrichment, thereby illustrating the broad utility of this methodology., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Introduction: The radioisotopes of bromine are uniquely suitable radiolabels for small molecule theranostic radiopharmaceuticals but are of limited availability due to production challenges. Significantly improved methods were developed for the production and radiochemical isolation of clinical quality 76 Br, 77 Br, and 80m Br. The radiochemical quality of the radiobromine produced using these methods was tested through the synthesis of a novel 77 Br-labeled inhibitor of poly (ADP-ribose) polymerase-1 (PARP-1), a DNA damage response protein., Methods: 76 Br, 77 Br, and 80m Br were produced in high radionuclidic purity via the proton irradiation of novel isotopically-enriched Co 76 Se, Co 77 Se, and Co 80 Se intermetallic targets, respectively. Radiobromine was isolated through thermal chromatographic distillation in a vertical furnace assembly. The 77 Br-labeled PARP inhibitor was synthesized via copper-mediated aryl boronic ester radiobromination., Results: Cyclotron production yields were 103 ± 10 MBq∙μA -1 ∙h -1 for 76 Br, 88 ± 10 MBq∙μA -1 ∙h -1 for 80m Br at 16 MeV and 17 ± 1 MBq∙μA -1 ∙h -1 for 77 Br at 13 MeV. Radiobromide isolation yields were 76 ± 11% in a small volume of aqueous solution. The synthesized 77 Br-labeled PARP-1 inhibitor had a measured apparent molar activity up to 700 GBq/μmol at end of synthesis., Conclusions: A novel selenium alloy target enabled clinical-scale production of 76 Br, 77 Br, and 80m Br with high apparent molar activities, which was used to for the production of a new 77 Br-labeled inhibitor of PARP-1., Advances in Knowledge: New methods for the cyclotron production and isolation of radiobromine improved the production capacity of 77 Br by a factor of three and 76 Br by a factor of six compared with previous methods., Implications for Patient Care: Preclinical translational research of 77 Br-based Auger electron radiotherapeutics, such as those targeting PARP-1, will require the production of GBq-scale 77 Br, which necessitates next-generation, high-yielding, isotopically-enriched cyclotron targets, such as the novel intermetallic Co 77 Se., Competing Interests: Declaration of competing interest No potential conflicts of interest relevant to this article exist., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Alpha-emitters can be pharmacologically delivered for irradiation of single cancer cells, but cellular lethality could be further enhanced by targeting alpha-emitters directly to the nucleus. PARP-1 is a druggable protein in the nucleus that is overexpressed in neuroblastoma compared with normal tissues and is associated with decreased survival in high-risk patients. To exploit this, we have functionalized a PARP inhibitor (PARPi) with an alpha-emitter astatine-211. This approach offers enhanced cytotoxicity from conventional PARPis by not requiring enzymatic inhibition of PARP-1 to elicit DNA damage; instead, the alpha-particle directly induces multiple double-strand DNA breaks across the particle track. Here, we explored the efficacy of [ 211 At]MM4 in multiple cancers and found neuroblastoma to be highly sensitive in vitro and in vivo Furthermore, alpha-particles delivered to neuroblastoma show antitumor effects and durable responses in a neuroblastoma xenograft model, especially when administered in a fractionated regimen. This work provides the preclinical proof of concept for an alpha-emitting drug conjugate that directly targets cancer chromatin as a therapeutic approach for neuroblastoma and perhaps other cancers., (©2019 American Association for Cancer Research.)

Previously, we reported a 3-(2-methoxyphenyl)-9-(3-((4-methyl-5-phenyl-4 H-1,2,4-triazol-3-yl)thio)propyl)-3,9-diazaspiro[5.5]undecane (1) compound with excellent dopamine D 3 receptor (D 3 R) affinity (D 3 R K i = 12.0 nM) and selectivity (D 2 R/D 3 R ratio = 905). Herein, we present derivatives of 1 with comparable D 3 R affinity (32, D 3 R K i = 3.2 nM, D 2 R/D 3 R ratio = 60) and selectivity (30, D 3 R K i = 21.0 nM, D 2 R/D 3 R ratio = 934). Fragmentation of 1 revealed orthosteric fragment 5a to express an unusually low D 3 R affinity ( K i = 2.7 μM). Compared to piperazine congener 31, which retains a high-affinity orthosteric fragment (5d, D 3 R K i = 23.9 nM), 1 was found to be more selective for the D 3 R among D 1 - and D 2 -like receptors and exhibited negligible off-target interactions at serotoninergic and adrenergic G-protein-coupled receptors (GPCRs), common off-target sites for piperazine-containing D 3 R scaffolds. This study provides a unique rationale for implementing weakly potent orthosteric fragments into D 3 R ligand systems to minimize drug promiscuity at other aminergic GPCR sites.

Poly(ADP-ribose)polymerase-1 inhibitor (PARPi) AZD2461 was designed to be a weak P-glycoprotein (P-gp) analogue of FDA approved olaparib. With this chemical property in mind, we utilized the AZD2461 ligand architecture to develop a CNS penetrant and PARP-1 selective imaging probe, in order to investigate PARP-1 mediated neuroinflammation and neurodegenerative diseases, such as Alzheimer's and Parkinson's. Our work led to the identification of several high-affinity PARPi, including AZD2461 congener 9e (PARP-1 IC 50  = 3.9 ± 1.2 nM), which was further evaluated as a potential 18 F-PET brain imaging probe. However, despite the similar molecular scaffolds of 9e and AZD2461, our studies revealed non-appreciable brain-uptake of [ 18 F]9e in non-human primates, suggesting AZD2461 to be non-CNS penetrant., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Poly(ADP-ribose) polymerase inhibitors (PARPi) are targeted therapeutics with enhanced selectivity and cytotoxicity in BRCA1/2 mutant cancer cells. AZD2461, a congener of FDA approved olaparib, is a potent PARPi with high affinity for PARP-1 and nonsubstrate for P-glycoprotein (P-gp), an attractive characteristic for cancer therapeutics. Analogues of AZD2461 were synthesized and profiled in BRCA1 functional and nonfunctional cell lines, revealing compounds ( 2 , 3 , and 5 ) of low cytotoxicity and excellent PARP-1 affinities (∼4-8 nM). In comparison to AZD2461, these agents were found to be less stimulating of P-gp, suggesting that these compounds may be excellent candidates for neurological applications where blood brain barrier penetrance is sought., Competing Interests: The authors declare no competing financial interest.

Development of poly(ADP-ribose) polymerase inhibitors (PARPi's) continues to be an attractive area of research due to synthetic lethality in DNA repair deficient cancers; however, PARPi's also have potential as therapeutics to prevent harmful inflammation. We investigated the pharmacological impact of incorporating spirodiamine motifs into the phthalazine architecture of FDA approved PARPi olaparib. Synthesized analogues were screened for PARP-1 affinity, enzyme specificity, catalytic inhibition, DNA damage, and cytotoxicity. This work led to the identification of 10e (12.6 ± 1.1 nM), which did not induce DNA damage at similar drug concentrations as olaparib. Interestingly, several worst in class compounds with low PARP-1 affinity, including 15b (4397 ± 1.1 nM), induced DNA damage at micromolar concentrations, which can explain the cytotoxicity observed in vitro. This work provides further evidence that high affinity PARPi's can be developed without DNA damaging properties offering potential new drugs for treating inflammatory related diseases.

Access to 211 At- and 125 I-radiolabeled compounds in excellent RCCs and RCYs was achieved in just 10 min at room temperature using a Cu catalyst. The reaction conditions are applicable to a broad class of aryl and heteroaryl boronic reagents with varying steric and electronic properties as well as late-stage astatination and iodination of anticancer PARP inhibitors. This protocol eliminates the traditional need for toxic organotin reagents, elevated temperatures, and extended reaction times, providing a more practical and environmentally friendly approach to developing α-emitting radiotherapeutics.

A series of potent and selective D 3 receptor (D 3 R) analogues with diazaspiro alkane cores were synthesized. Radioligand binding of compounds 11, 14, 15a, and 15c revealed favorable D 3 R affinity (K i = 12-25.6 nM) and were highly selective for D 3 R vs D 3 R (ranging from 264- to 905-fold). Variation of these novel ligand architectures can be achieved using our previously reported 10-20 min benchtop C-N cross-coupling methodology, affording a broad range of arylated diazaspiro precursors.

Application of Buchwald-Hartwig catalysis for development of biologically relevant arylspirodiamine compounds is reported. This synthetic methodology requires no inert atmosphere and affords yields up to 93% in just 20 min. Linear and sterically hindered angular spirodiamines in salt and free-base form are coupled with electron-rich and -withdrawing aryl chlorides, demonstrating a broad scope and applicability of this protocol.

A facile Pd-catalyzed methodology providing an efficient synthetic route to biologically relevant arylpiperazines under aerobic conditions is reported. Electron donating and sterically hindered aryl chlorides were aminated to afford yields up to 97%, with examples using piperazine as solvent, illustrating an ecofriendly, cost-effective synthesis of these privileged structures.

Development of CCC-NHC pincer Co complexes via transmetalation from Zr is reported. Formation of these air-stable Co(iii) complexes was achieved through use of a CoCl2 or Co(acac)3in situ or with a discrete CCC-NHC pincer Zr transmetallating agent. Preliminary activity in the hydroboration of styrene is reported. This facile methodology will further the development of CCC-NHC pincer first-row transition metal complexes.