Covalent and noncovalent strategies for targeting Lys102 in HIV-1 reverse transcriptase.

Reverse transcriptase (RT) is one of three key proteins responsible for the replication cycle of HIV-1 in the host. Several classes of inhibitors have been developed to target the enzyme, with non-nucleoside reverse transcriptase inhibitors forming first-line treatment. Previously, covalent RT inhibitors have been identified and found to bind irreversibly to commonly mutated residues such as Y181C.

Progress on the Pharmacological Targeting of Janus Pseudokinases.

The Janus kinases (JAKs) are key components of the JAK-STAT signaling pathway and are involved in myriad physiological processes. Though they are the molecular targets of many FDA-approved drugs, these drugs manifest adverse effects due in part to their inhibition of the requisite JAK kinase activity. However, the JAKs uniquely possess an integrated pseudokinase domain (JH2) that regulates the adjacent kinase domain (JH1).

Covalent Modification of the JH2 Domain of Janus Kinase 2.

Probe molecules that covalently modify the JAK2 pseudokinase domain (JH2) are reported. Selective targeting of JH2 domains over the kinase (JH1) domains is a necessary feature for ligands intended to evaluate JH2 domains as therapeutic targets. The JH2 domains of three Janus kinases (JAK1, JAK2, and TYK2) possess a cysteine residue in the catalytic loop that does not occur in their JH1 domains.

Insights on JAK2 Modulation by Potent, Selective, and Cell-Permeable Pseudokinase-Domain Ligands.

JAK2 is a non-receptor tyrosine kinase that regulates hematopoiesis through the JAK-STAT pathway. The pseudokinase domain (JH2) is an important regulator of the activity of the kinase domain (JH1). V617F mutation in JH2 has been associated with the pathogenesis of various myeloproliferative neoplasms, but JAK2 JH2 has been poorly explored as a pharmacological target.

Conversion of a False Virtual Screen Hit into Selective JAK2 JH2 Domain Binders Using Convergent Design Strategies.

The Janus kinase 2 (JAK2) pseudokinase domain (JH2) is an ATP-binding domain that regulates the activity of the catalytic tyrosine kinase domain (JH1). Dysregulation of JAK2 JH1 signaling caused by the V617F mutation in JH2 is implicated in various myeloproliferative neoplasms. To explore if JAK2 activity can be modulated by a small molecule binding to the ATP site in JH2, we have developed several ligand series aimed at selectively targeting the JAK2 JH2 domain.

Indoloxytriazines as binding molecules for the JAK2 JH2 pseudokinase domain and its V617F variant.

Small molecules that selectively bind to the pseudokinase JH2 domain over the JH1 kinase domain of JAK2 kinase are sought. Virtual screening led to the purchase of 17 compounds among which 9 were found to bind to V617F JAK2 JH2 with affinities of 40 - 300 μM in a fluorogenic assay. Ten analogues were then purchased yielding 9 additional active compounds.

SAR Matrices Enable Discovery of Mixed Efficacy μ-Opioid Receptor Agonist Peptidomimetics with Simplified Structures through an Aromatic-Amine Pharmacophore.

We previously described the development of potent μ-opioid receptor (MOR)-agonist/δ-opioid receptor (DOR)-antagonist peptidomimetic ligands as an approach toward effective analgesics with reduced side effects. In this series, a tetrahydroquinoline (THQ) or substituted phenyl is employed to link two key pharmacophore elements, a dimethyltyrosine amino acid and typically an aromatic pendant. Using new and previously reported analogues, we constructed a structure-activity relationship (SAR) matrix that probes the utility of previously reported amine pendants.

Aromatic-Amine Pendants Produce Highly Potent and Efficacious Mixed Efficacy μ-Opioid Receptor (MOR)/δ-Opioid Receptor (DOR) Peptidomimetics with Enhanced Metabolic Stability.

We previously reported a novel SAR campaign that converted a metabolically unstable series of μ-opioid receptor (MOR) agonist/δ-opioid receptor (DOR) antagonist bicyclic core peptidomimetics with promising analgesic activity and reduced abuse liabilities into a more stable series of benzylic core analogues. Herein, we expanded the SAR of that campaign and determined that the incorporation of amines into the benzylic pendant produces enhanced MOR-efficacy in this series, whereas the reincorporation of an aromatic ring into the pendant enhanced MOR-potency. Two compounds, which contain a piperidine () or an isoindoline () pendant, retained the desired opioid profile , possessed metabolic half-lives of greater than 1 h in mouse liver microsomes (MLMs), and were active antinociceptive agents in the acetic acid stretch assay (AASA) at subcutaneous doses of 1 mg/kg.

Structural Simplification of a Tetrahydroquinoline-Core Peptidomimetic μ-Opioid Receptor (MOR) Agonist/δ-Opioid Receptor (DOR) Antagonist Produces Improved Metabolic Stability.

We have previously reported a series of μ-opioid receptor (MOR) agonist/δ-opioid receptor (DOR) antagonist ligands to serve as potential nonaddictive opioid analgesics. These ligands have been shown to be active in vivo, do not manifest withdrawal syndromes or reward behavior in conditioned-place preference assays in mice, and do not produce dependence. Although these attributes are promising, these analogues exhibit poor metabolic stability in mouse liver microsomes, likely due to the central tetrahydroquinoline scaffold in this series.

5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells.

Plants of the Amaryllidaceae family produce a large variety of alkaloids and non-basic secondary metabolites, many of which are investigated for their promising anticancer activities. Of these, crinine-type alkaloids based on the 5,10b-ethanophenanthridine ring system were recently shown to be effective at inhibiting proliferation of cancer cells resistant to various pro-apoptotic stimuli and representing tumors with dismal prognoses refractory to current chemotherapy, such as glioma, melanoma, non-small-cell lung, esophageal, head and neck cancers, among others. Using this discovery as a starting point and taking advantage of a concise biomimetic route to the crinine skeleton, a collection of crinine analogues were synthetically prepared and evaluated against cancer cells.