Reversible male contraception by targeted inhibition of serine/threonine kinase 33.

Men or mice with homozygous serine/threonine kinase 33 () mutations are sterile owing to defective sperm morphology and motility. To chemically evaluate STK33 for male contraception with STK33-specific inhibitors, we screened our multibillion-compound collection of DNA-encoded chemical libraries, uncovered potent STK33-specific inhibitors, determined the STK33 kinase domain structure bound with a truncated hit CDD-2211, and generated an optimized hit CDD-2807 that demonstrates nanomolar cellular potency (half-maximal inhibitory concentration = 9.2 nanomolar) and favorable metabolic stability.

Identification of potent pan-ephrin receptor kinase inhibitors using DNA-encoded chemistry technology.

EPH receptors (EPHs), the largest family of tyrosine kinases, phosphorylate downstream substrates upon binding of ephrin cell surface-associated ligands. In a large cohort of endometriotic lesions from individuals with endometriosis, we found that and expressions are increased in endometriotic lesions relative to normal eutopic endometrium. Because signaling through EPHs is associated with increased cell migration and invasion, we hypothesized that chemical inhibition of EPHA2/4 could have therapeutic value.

CYP3A Mediates an Unusual C(sp)-C(sp) Bond Cleavage via Ipso-Addition of Oxygen in Drug Metabolism.

Mammalian cytochrome P450 drug-metabolizing enzymes rarely cleave carbon-carbon (C-C) bonds and the mechanisms of such cleavages are largely unknown. We identified two unusual cleavages of non-polar, unstrained C(sp)-C(sp) bonds in the FDA-approved tyrosine kinase inhibitor pexidartinib that are mediated by CYP3A4/5, the major human phase I drug metabolizing enzymes. Using a synthetic ketone, we rule out the Baeyer-Villiger oxidation mechanism that is commonly invoked to address P450-mediated C-C bond cleavages.

Concise Syntheses of Microsomal Metabolites of a Potent OXE (Oxoeicosanoid) Receptor Antagonist.

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is the most potent eosinophil chemoattractant among lipid mediators, and its actions are mediated by the selective oxoeicosanoid (OXE) receptor. Our group previously developed a highly potent indole-based OXE antagonist, S-C025, with an IC value of 120 pM. S-C025 was converted to a number of metabolites in the presence of monkey liver microsomes.

Advancing ASMS with LC-MS/MS for the discovery of novel PDCL2 ligands from DNA-encoded chemical library selections.

Background: A safe, effective, and reversible nonhormonal male contraceptive drug is greatly needed for male contraception as well as for circumventing the side effects of female hormonal contraceptives. Phosducin-like 2 (PDCL2) is a testis-specific phosphoprotein in mice and humans. We recently found that male PDCL2 knockout mice are sterile due to globozoospermia caused by impaired sperm head formation, indicating that PDCL2 is a potential target for male contraception.

A unified strategy for the total syntheses of eribulin and a macrolactam analogue of halichondrin B.

A unified synthetic route for the total syntheses of eribulin and a macrolactam analog of halichondrin B is described. The key to the success of the current synthetic approach includes the employment of our reverse approach for the construction of cyclic ether structural motifs and a modified intramolecular cyclization reaction between alkyl iodide and aldehyde functionalities to establish the all-carbon macrocyclic framework of eribulin. These syntheses, together with our previous work on the total syntheses of halichondrin B and norhalichondrin B, demonstrate and validate the powerful reverse approach in the construction of cyclic ether structural motifs.

The testis-specific E3 ubiquitin ligase RNF133 is required for fecundity in mice.

Background: Ubiquitination is a post-translational modification required for a number of physiological functions regulating protein homeostasis, such as protein degradation. The endoplasmic reticulum (ER) quality control system recognizes and degrades proteins no longer needed in the ER through the ubiquitin-proteasome pathway. E2 and E3 enzymes containing a transmembrane domain have been shown to function in ER quality control.

Metabolism of anti-inflammatory OXE (oxoeicosanoid) receptor antagonists by nonhuman primates.

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is the only product of the proinflammatory 5-lipoxygenase pathway with potent chemoattractant effects for human eosinophils, suggesting an important role in eosinophilic diseases such as asthma. 5-Oxo-ETE, acting through its selective OXE receptor, induces dermal eosinophilia in both humans and monkeys. To block its effects, we designed selective indole-based OXE antagonists containing hexyl (S-230) or phenylhexyl (S-C025 and S-Y048) side chains, which inhibit allergen-induced dermal and pulmonary inflammation in monkeys, suggesting that they may be useful therapeutic agents in humans.

A Highly Convergent Total Synthesis of Norhalichondrin B.

A new synthetic strategy for the total synthesis of norhalichondrin B featuring a highly convergent approach and our recently disclosed reverse approach for the synthesis of cyclic ether structural motifs is disclosed. Resulting in the shortest route to norhalichondrin B disclosed thus far, the reported total synthesis was achieved through the synthesis of two almost equally complex fragments whose coupling and short elaboration sequence featured an essential epimerization of the C16 stereocenter occurring concurrently with a simple acid-induced deprotection, a tactic based on a prior study along the synthetic route. This unprecedented strategy within the halichondrin family of natural products could find practical application to the synthesis of other more or less complex natural or designed halichondrin analogues.

Targeting the OXE receptor with a selective antagonist inhibits allergen-induced pulmonary inflammation in non-human primates.

Background And Purpose: The 5-lipoxygenase product, 5-oxo-ETE (5-oxo-6,8,11,14-eicosatetraenoic acid), is a potent chemoattractant for eosinophils and neutrophils. However, little is known about its pathophysiological role because of the lack of a rodent ortholog of the oxoeicosanoid (OXE) receptor. The present study aimed to determine whether the selective OXE receptor antagonist S-Y048 can inhibit allergen-induced pulmonary inflammation in a monkey model of asthma.

A Reverse Approach to the Total Synthesis of Halichondrin B.

A new strategy is described for the total synthesis of halichondrin B featuring reversal of the sequential construction of a number of its cyclic ethers from the classical approach by instead forming C-O bonds first followed by C-C bond formation. Employing the Nicholas reaction to generate linear ethers as precursors for the total synthesis of halichondrin B and other members of the halichondrin and eribulin families of compounds, this novel approach provides new opportunities for the development of improved syntheses of these complex and valuable compounds. In this Article, we report the syntheses of defined fragments , , , and .

Design, Synthesis, and Biological Evaluation of Tubulysin Analogues, Linker-Drugs, and Antibody-Drug Conjugates, Insights into Structure-Activity Relationships, and Tubulysin-Tubulin Binding Derived from X-ray Crystallographic Analysis.

Molecular design, synthesis, and biological evaluation of tubulysin analogues, linker-drugs, and antibody-drug conjugates are described. Among the new discoveries reported is the identification of new potent analogues within the tubulysin family that carry a C11 alkyl ether substituent, rather than the usual ester structural motif at that position, a fact that endows the former with higher plasma stability than that of the latter. Also described herein are X-ray crystallographic analysis studies of two tubulin-tubulysin complexes formed within the α/β interface between two tubulin heterodimers and two highly potent tubulysin analogues, one of which exhibited a different binding mode to the one previously reported for tubulysin M.

Novel highly potent OXE receptor antagonists with prolonged plasma lifetimes that are converted to active metabolites in vivo in monkeys.

Background And Purpose: The 5-lipoxygenase product 5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-oxo-ETE), acting through the OXE receptor, is a potent eosinophil chemoattractant that may be an important proinflammatory mediator in eosinophilic diseases such as asthma. We previously identified a series of indole-based OXE receptor antagonists that rapidly appear in the blood following oral administration but have limited lifetimes. The objective of this study was to increase the potency and plasma half-lives of these compounds and thereby identify the optimal candidate for future preclinical studies in monkeys, as rodents do not have an OXE receptor orthologue.

Inhibition of allergen-induced dermal eosinophilia by an oxoeicosanoid receptor antagonist in non-human primates.

Background And Purpose: 5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE), acting via the OXE receptor, is unique among 5-lipoxygenase products in its ability to directly induce human eosinophil migration, suggesting its involvement in eosinophilic diseases. To address this hypothesis, we synthesized selective indole-based OXE receptor antagonists. Because rodents lack an OXE receptor orthologue, we sought to determine whether these antagonists could attenuate allergen-induced skin eosinophilia in sensitized monkeys.

Novel Highly Potent and Metabolically Resistant Oxoeicosanoid (OXE) Receptor Antagonists That Block the Actions of the Granulocyte Chemoattractant 5-Oxo-6,8,11,14-Eicosatetraenoic Acid (5-oxo-ETE).

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is a potent lipid mediator that induces tissue eosinophilia via the selective OXE receptor (OXE-R), which is an attractive therapeutic target in eosinophilic diseases. We previously identified indole OXE-R antagonists that block 5-oxo-ETE-induced primate eosinophil activation. Although these compounds possess good oral absorption, their plasma levels decline rapidly due to extensive oxidation of their hexyl side chain.

Metabolism and pharmacokinetics of a potent N-acylindole antagonist of the OXE receptor for the eosinophil chemoattractant 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) in rats and monkeys.

We previously identified the indole 264 as a potent in vitro antagonist of the human OXE receptor that mediates the actions of the powerful eosinophil chemoattractant 5-oxo-ETE. No antagonists of this receptor are currently commercially available or are being tested in clinical studies. The lack of a rodent ortholog of the OXE receptor has hampered progress in this area because of the unavailability of commonly used mouse or rat animal models.

Structure-activity relationship study of β-oxidation resistant indole-based 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) receptor antagonists.

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is formed from 5S-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE) by the 5-lipoxygenase (5-LO) pathway under conditions associated with oxidative stress. 5-Oxo-ETE is an important pro-inflammatory mediator, which stimulates the migration of eosinophils via a selective G-protein coupled receptor, known as the OXE receptor (OXE-R). Previously, we designed and synthesized structural mimics of 5-oxo-ETE such as 1 using an indole scaffold.

In vivo α-hydroxylation of a 2-alkylindole antagonist of the OXE receptor for the eosinophil chemoattractant 5-oxo-6,8,11,14-eicosatetraenoic acid in monkeys.

We have developed a selective indole antagonist (230) targeting the OXE receptor for the potent eosinophil chemoattractant 5-oxo-ETE (5-oxo-6,8,11,14-eicosatetraenoic acid), that may be useful for the treatment of eosinophilic diseases such as asthma. In previous studies we identified ω2-oxidation of the hexyl side chain of racemic 230 as a major metabolic route in monkeys, but also obtained evidence for another pathway that appeared to involve hydroxylation of the hexyl side chain close to the indole. The present study was designed to investigate the metabolism of the active S-enantiomer of 230 (S230) and to identify the novel hydroxy metabolite and its chirality.

Pharmacokinetics and Metabolism of Selective Oxoeicosanoid (OXE) Receptor Antagonists and Their Effects on 5-Oxo-6,8,11,14-eicosatetraenoic Acid (5-Oxo-ETE)-Induced Granulocyte Activation in Monkeys.

The potent eosinophil chemoattractant 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is a 5-lipoxygenase product that acts via the selective OXE receptor, which is present in many species, but not rodents. We previously reported that the indole 230 is a potent human OXE receptor antagonist. The objective of the present study was to determine whether the monkey would be a suitable animal model to investigate its pharmaceutical potential.

Biosynthesis and actions of 5-oxoeicosatetraenoic acid (5-oxo-ETE) on feline granulocytes.

The 5-lipoxygenase product 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is the most powerful human eosinophil chemoattractant among lipid mediators and could play a major pathophysiological role in eosinophilic diseases such as asthma. Its actions are mediated by the OXE receptor, orthologs of which are found in many species from humans to fish, but not rodents. The unavailability of rodent models to examine the pathophysiological roles of 5-oxo-ETE and the OXE receptor has substantially hampered progress in this area.

Two Potent OXE-R Antagonists: Assignment of Stereochemistry.

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is formed by the oxidation of 5-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-HETE), which is a major metabolite of enzymatic oxidation of arachidonic acid (AA). 5-Oxo-ETE is the most potent lipid chemoattractant for human eosinophils. Its actions are mediated by the selective OXE receptor, which is therefore an attractive target in eosinophilic diseases such as allergic rhinitis and asthma.

Base-dependent formation of cis and trans olefins and their application in the synthesis of 5-oxo-ETE receptor antagonists.

5-Oxo-ETE is the most potent eosinophil chemoattractant among lipid mediators. We have developed two 5-oxo-ETE receptor antagonists. In the course of the work, we have developed a procedure to selectively introduce a cis and trans double bond in an alkyl side chain.

Inhibition of 5-oxo-6,8,11,14-eicosatetraenoic acid-induced activation of neutrophils and eosinophils by novel indole OXE receptor antagonists.

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is a 5-lipoxygenase product that is a potent granulocyte chemoattractant, which induces the infiltration of eosinophils into human skin when injected intradermally. It could therefore be an important proinflammatory mediator in eosinophilic diseases such as asthma and allergic rhinitis, and the OXE receptor, which mediates its actions, is therefore an attractive drug target. Using a structure-based approach in which substituents mimicking the essential polar (C1-C5) and hydrophobic (C15-C20) regions of 5-oxo-ETE were incorporated on an indole scaffold, we identified two potent selective OXE antagonists with IC50 values of about 30 nM.