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SummaryPINK1 loss-of-function mutations and exposure to mitochondrial toxins are causative for Parkinson’s disease (PD) and Parkinsonism, respectively. We demonstrate that pathological α-synuclein deposition, the hallmark pathology of idiopathic PD, induces mitochondrial dysfunction and impairs mitophagy, driving accumulation of the PINK1 substrate pS65-Ubiquitin (pUb) in primary neurons and in vivo. We synthesized MTK458, a brain penetrant small molecule that binds to PINK1 and stabilizes an active heterocomplex, thereby increasing mitophagy. MTK458 mediates clearance of α-synuclein pathology in PFF seeding models in vitro and in vivo and reduces pUb. We developed an ultrasensitive assay to quantify pUb levels in plasma and observed an increase in pUb in PD subjects that correlates with disease progression, paralleling our observations in PD models. Our combined findings from preclinical PD models and patient biofluids suggest that pharmacological activation of PINK1 is worthy of further study as a therapeutic strategy for disease modification in PD.HighlightsDiscovery of a plasma Parkinson’s Disease biomarker candidate, pS65-Ubiquitin (pUb)Plasma pUb levels correlate with disease status and progression in PD patients.Identification of a potent, brain penetrant PINK1 activator, MTK458MTK458 selectively activates PINK1 by stimulating dimerization and stabilization of the PINK1/TOM complexMTK458 drives clearance of α-synuclein pathology and normalizes pUb in in vivo Parkinson’s models

New strategies to potentially improve drug safety and efficacy emerge with allosteric programs. Biased allosteric modulators can be designed with high subtype selectivity and defined receptor signaling endpoints, however, selecting the most meaningful parameters for optimization can be perplexing. Historically, "potency hunting" at the expense of physicochemical and pharmacokinetic optimization has led to numerous tool compounds with excellent pharmacological properties but no path to drug development. Conversely, extensive physicochemical and pharmacokinetic screening with only post hoc bias and allosteric characterization has led to inefficacious compounds or compounds with on-target toxicities. This field is rapidly evolving with new mechanistic understanding, changes in terminology, and novel opportunities. The intent of this digest is to summarize current understanding and debates within the field. We aim to discuss, from a medicinal chemistry perspective, the parameter choices available to drive SAR.

Benzothiazole amides were identified as TRPV1 antagonists from high throughput screening using recombinant human TRPV1 receptor and structure-activity relationships were explored to pinpoint key pharmacophore interactions. By increasing aqueous solubility, through the attachment of polar groups to the benzothiazole core, and enhancing metabolic stability, by blocking metabolic sites, the drug-like properties and pharmokinetic profiles of benzothiazole compounds were sufficiently optimized such that their therapeutic potential could be verified in rat pharmacological models of pain.

Two strategies were developed toward the stereocontrolled synthesis of 8-aryl-3-hydroxy-4-amino-2,7-diisopropyloctanoic acids with predetermined stereogenic centers. This is a generic motif in a new class of potent inhibitors of the enzyme renin, exemplified by CGP-60536B. The synthesis relies on the utilization of L-pyroglutamic acid as chiron, and proceeds through the incorporation of required functionality by exploiting internal induction. One of the strategies shows the power of visual imagery in synthesis planning, akin to a Dali-like representation of objects that can be viewed in more than one way. Thus, the entire carbon skeleton of the target molecule is encompassed in a partially functionalized bicyclic indolizidinone precursor. In a second strategy, an intermediate common to the first approach is elaborated into an appended gamma-lactone which is alkylated through enolate chemistry and ultimately transformed into the intended target compound. X-ray crystallography was used to corroborate the structures and stereochemistries of several intermediates.

N-t-Butoxycarbonyl-O-sulfonyl-substituted hydroxylamines react with soft enolates to yield O-t-butoxycarbonylamino derivatives rather than the expected Boc-protected amino acids. The reaction is limited to enolates of β-dicarbonyl compounds. Decarboxylation of the resultant tricarbonyl compound affords malonyl α-alkyl O-t-butoxycarbonylamino derivatives.

Cannabinoid CB1 receptor agonists exhibit potent analgesic effects in rodents and humans, but their clinical utility as analgesic drugs is often limited by centrally mediated side effects. We report herein the preparation of N-methyl-3-(tetrahydro-2H-pyran-4-yl)-2,3,4,9-tetrahydro-1H-carbazole-6-carboxamides as a novel class of hCB1/hCB2 dual agonists with attractive physicochemical properties. More specifically, (R)-N,9-dimethyl-N-(4-(methylamino)-4-oxobutyl)-3-(tetrahydro-2H-pyran-4-yl)-2,3,4,9-tetrahydro-1H-carbazole-6-carboxamide, displayed an extremely low level of CNS penetration (Rat Cbr/Cplasma = 0.005 or 0.5%) and was devoid of CNS side effects during pharmaco-dynamic testing.

Introduction - The Myc proteins are transcription factors that have essential roles in cell growth and proliferation by both positively and negatively regulating gene expression. Mutation, amplification, or activation of the MYC oncogene family is one of the most frequent events associated with cancer. In acute myeloid leukemia (AML), c-Myc is commonly activated and plays an important role in the initiation and maintenance of the disease. In particular, c-Myc is upregulated by activating mutations of the Flt3 receptor tyrosine kinase, one of the most prevalent types of mutations in AML, and also by the AML-associated fusion proteins AML1-ETO, PML/RARα, and PLZF/RARα. It has also been shown that c-Myc is negatively regulated by C/EBPα, a transcription factor essential for granulocytic differentiation, and that c-Myc expression is elevated in myeloid leukemias in which C/EBPα is mutated. Additionally, c-Myc is stabilized in AML with mutations leading to aberrant cytoplasmic localization of nucleophosmin (NPM), the most frequent genetic alteration in AML without karyotypic aberrations. Importantly, the MYC gene itself, located at 8q24, has been found to be one of the most commonly amplified regions in AML. Lastly, the importance of c-Myc in myeloid leukemogenesis has been further demonstrated by the induction of myeloid leukemias in mouse models overexpressing c-Myc in bone marrow progenitors. Methods - In the current study, we disrupt MYC transcription in AML blasts, by interfering with chromatin-dependent signal transduction to RNA polymerase, specifically by inhibiting the acetyl-lysine recognition domains (bromodomains, specifically BRD4) of putative coactivator proteins implicated in transcriptional initiation and elongation. Results - Following extensive chemical optimization and biological characterization, we identified two advanced pre-clinical candidates, EP11313 and EP11336. These compounds have excellent affinity for BRD4 and achieve high in-vivo exposure in animal models. Both agents possess drug-like physical characteristics, and their pharmacologic properties compared favorably to the BRD4 inhibitor IBET-762 (GSK525762A). Respectively for IBET-762, EP11313 and EP11336 we calculated BRD4 IC50 (23, 7, 5 nM), BRD4 KD (55, 2, 6 nM), molecular weight (424, 415, 445 Da), solubility (194, 20, 85 μM), cLogP (1.8, 3.7, 3.0), PSA (81, 78, 98 Ǻ2), MDR-MDCK Efflux ratio BA/AB (27.9, 1.3, 1.9) and MDR-MDCK Papp (1.1, 7.3, 10.2). In vitro, both molecules have nanomolar anti-leukemic activity across a panel c-myc dysregulated AML cell lines (OCI-AML2, OCI-AML3, KG-1a, HL-60, MV-411 and NB-4). Growth inhibition was variable and context dependent (GI50 range: 265 nM - 1618 nM). Following a brief incubation in-vitro, both EP11313 and EP11336 lead to activation of caspase 3 and initiation of apoptotic cell death. Over-expression of c-myc is known to impair myeloid differentiation in response to the retinoid all-trans-retinoic acid (ATRA) in AML, considering this and the research interests of our group in broadening the anti-leukemic effects of ATRA, we showed that ATRA combined with bromodomain inhibition led to greater cell kill in vitro than was observed for ATRA, or either bromodomain inhibitor tested alone (see figure). Conclusions - Both EP11313 and EP11336 are currently in late pre-clinical development, and are being optimized for first in man studies in AML and other tumor types. Updated information on the in-vivo activity of these compounds and mechanism of action in AML will be presented. Figure 1. The BET bromodomain inhibitors EP11313 and EP11336, impair the viability of AML blasts in vitro and have synergistic activity when combined with the retinoid all-trans -retinoic acid (AtRA). MV-411 cells were incubated with the indicated concentrations of EP11313, EP11336 and AtRA for 48 hours. Cell viability was measured using a bioluminescence assay (CellTiter-Glo¨, left) and induction of caspase 3, was measured by FACS (right). Growth inhibition (GI) in OCI-AML3 cells was calculated using linear extrapolation (top). Figure 1. The BET bromodomain inhibitors EP11313 and EP11336, impair the viability of AML blasts in vitro and have synergistic activity when combined with the retinoid all-trans -retinoic acid (AtRA). MV-411 cells were incubated with the indicated concentrations of EP11313, EP11336 and AtRA for 48 hours. Cell viability was measured using a bioluminescence assay (CellTiter-Glo¨, left) and induction of caspase 3, was measured by FACS (right). Growth inhibition (GI) in OCI-AML3 cells was calculated using linear extrapolation (top). Disclosures Johnstone: Epigenetix: Employment. Albert:Epigenetix: Employment. Collard:Epigenetix: Employment.

N-t-Butoxycarbonyl-O-sulfonyl-substituted hydroxylamines react with soft enolates to yield O-t-butoxycarbonylamino derivatives rather than the expected Boc-protected amino acids. The reaction is limited to enolates of β-dicarbonyl compounds. Decarboxylation of the resultant tricarbonyl compound affords malonyl α-alkyl O-t-butoxycarbonylamino derivatives.

The total synthesis of dysinosin A, a novel member of the aeruginosin group of marine natural products is discussed. The stereocontrolled synthesis also confirms the proposed structure and absolute stereochemistry of the natural product.

The structure and absolute configuration of the marine antithrombotic product dysinosin A was confirmed by total synthesis. The strategy involved disconnections to three subunits, of which two were synthesized from the readily available l-glutamic acid, d-leucine, and d-mannitol. The Grubbs olefin metathesis carbocyclization reaction was utilized to prepare two intermediates.