Gnanasambandam Kumaravel

Piperazine derivatives of [1,2,4]triazolo[1,5-a][1,3,5]triazine as potent and selective adenosine A2a receptor antagonists.

The [1,2,4]triazolo[1,5-a]triazine derivative 3, more commonly known in the field of adenosine research as ZM-241385, has previously been demonstrated to be a potent and selective adenosine A2a receptor antagonist, although with limited oral bioavailability. This [1,2,4]triazolo[1,5-a]triazine core structure has now been improved by incorporating various piperazine derivatives. With some preliminary optimization, the A2a binding affinity of some of the best piperazine derivatives is almost as good as that of compound 3. The selectivity level over the adenosine A1 receptor subtype for some of the more active analogues is also fairly high, > 400-fold in some cases. Many compounds within this piperazine series of [1,2,4]triazolo[1,5-a]triazine have now been shown to have good oral bioavailability in the rat, with some as high as 89% (compound 35). More significantly, some piperazines derivatives of [1,2,4]triazolo[1,5-a]triazine also possessed good oral efficacy in rodent models of Parkinsons disease. For instance, compound 34 was orally active in the rat catalepsy model at 3 mg/kg. In the 6-hydroxydopamine-lesioned rat model, this compound was also quite effective, with a minimum effective dose of 3 mg/kg po.

19F NMR MONITORING OF A SNAR REACTION ON SOLID SUPPORT

Gel-phase 19F and MAS 19F and 13C NMR for monitoring the progress of an on-resin SNAr reaction is demonstrated.

Small Molecule Inhibition of the TNF Family Cytokine CD40 Ligand Through a Subunit Fracture Mechanism

BIO8898 is one of several synthetic organic molecules that have recently been reported to inhibit receptor binding and function of the constitutively trimeric tumor necrosis factor (TNF) family cytokine CD40 ligand (CD40L, aka CD154). Small molecule inhibitors of protein-protein interfaces are relatively rare, and their discovery is often very challenging. Therefore, to understand how BIO8898 achieves this feat, we characterized its mechanism of action using biochemical assays and X-ray crystallography. BIO8898 inhibited soluble CD40L binding to CD40-Ig with a potency of IC(50) = 25 μM and inhibited CD40L-dependent apoptosis in a cellular assay. A co-crystal structure of BIO8898 with CD40L revealed that one inhibitor molecule binds per protein trimer. Surprisingly, the compound binds not at the surface of the protein but by intercalating deeply between two subunits of the homotrimeric cytokine, disrupting a constitutive protein-protein interface and breaking the proteins 3-fold symmetry. The compound forms several hydrogen bonds with the protein, within an otherwise hydrophobic binding pocket. In addition to the translational splitting of the trimer, binding of BIO8898 was accompanied by additional local and longer-range conformational perturbations of the protein, both in the core and in a surface loop. Binding of BIO8898 is reversible, and the resulting complex is stable and does not lead to detectable dissociation of the protein trimer. Our results suggest that a set of core aromatic residues that are conserved across a subset of TNF family cytokines might represent a generic hot-spot for the induced-fit binding of trimer-disrupting small molecules.

Synapto-depressive effects of amyloid beta require PICK1

Amyloid beta (Aβ), a key component in the pathophysiology of Alzheimers disease, is thought to target excitatory synapses early in the disease. However, the mechanism by which Aβ weakens synapses is not well understood. Here we showed that the PDZ domain protein, protein interacting with C kinase 1 (PICK1), was required for Aβ to weaken synapses. In mice lacking PICK1, elevations of Aβ failed to depress synaptic transmission in cultured brain slices. In dissociated cultured neurons, Aβ failed to reduce surface α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptor subunit 2, a subunit of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptors that binds with PICK1 through a PDZ ligand–domain interaction. Lastly, a novel small molecule (BIO922) discovered through structure‐based drug design that targets the specific interactions between GluA2 and PICK1 blocked the effects of Aβ on synapses and surface receptors. We concluded that GluA2–PICK1 interactions are a key component of the effects of Aβ on synapses.

Discovery of BIIB042, a Potent, Selective, and Orally Bioavailable γ-Secretase Modulator.

We have investigated a novel series of acid-derived γ-secretase modulators as a potential treatment of Alzheimers disease. Optimization based on cellular potency and brain pharmacodynamics after oral dosing led to the discovery of 10a (BIIB042). Compound 10a is a potent γ-secretase modulator, which lowered Aβ42, increased Aβ38, but had little to no effect on Aβ40 levels both in vitro and in vivo. In addition, compound 10a did not affect Notch signaling in our in vitro assessment. Compound 10a demonstrated excellent pharmacokinetic parameters in multiple species. Oral administration of 10a significantly reduced brain Aβ42 levels in CF-1 mice and Fischer rats, as well as plasma Aβ42 levels in cynomolgus monkeys. Compound 10a was selected as a candidate for preclinical safety evaluation.

Discovery of 4-aminomethylphenylacetic acids as γ-secretase modulators via a scaffold design approach.

Starting from literature examples of nonsteroidal anti-inflammatory drugs (NSAIDs)-type carboxylic acid γ-secretase modulators (GSMs) and using a scaffold design approach, we identified 4-aminomethylphenylacetic acid 4 with a desirable γ-secretase modulation profile. Scaffold optimization led to the discovery of a novel chemical series, represented by 6b, having improved brain penetration. Further SAR studies provided analog 6q that exhibited a good pharmacological profile. Oral administration of 6q significantly reduced brain Aβ42 levels in mice and rats.

Stereochemistry activity relationship of orally active tetralin S1P agonist prodrugs

Modifying FTY720, an immunosuppressant modulator, led to a new series of well phosphorylated tetralin analogs as potent S1P1 receptor agonists. The stereochemistry effect of tetralin ring was probed, and (-)-(R)-2-amino-2-((S)-6-octyl-1,2,3,4-tetrahydronaphthalen-2-yl)propan-1-ol was identified as a good SphK2 substrate and potent S1P1 agonist with good oral bioavailability.