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[Image: see text] The selectivity of histone deacetylase inhibitors (HDACis) is greatly impacted by the zinc binding groups. In an effort to search for novel zinc binding groups, we applied a parallel medicinal chemistry (PMC) strategy to quickly synthesize substituted benzamide libraries. We discovered a series containing 2-substituted benzamides as the zinc binding group which afforded highly selective and potent HDAC3 inhibitors, exemplified by compound 16 with a 2-methylthiobenzamide. Compound 16 inhibited HDAC3 with an IC(50) of 30 nM and with unprecedented selectivity of >300-fold over all other HDAC isoforms. Interestingly, a subtle change of the 2-methylthio to a 2-hydroxy benzamide in 20 retains HDAC3 potency but loses all selectivity over HDAC 1 and 2. This significant difference in selectivity was rationalized by X-ray crystal structures of HDACis 16 and 20 bound to HDAC2, revealing different binding modes to the catalytic zinc ion. This series of HDAC3 selective inhibitors served as tool compounds for investigating the minimal set of HDAC isoforms that must be inhibited for the HIV latency activation in a Jurkat 2C4 cell model and potentially as leads for selective HDAC3 inhibitors for other indications.

[Image: see text] HIV persistence in latently infected, resting CD4(+) T cells is broadly considered a barrier to eradicate HIV. Activation of the provirus using latency-reversing agents (LRAs) followed by immune-mediated clearance to purge reservoirs has been touted as a promising therapeutic approach. Histone deacetylases (HDACs) and histone acetyltransferases (HATs) control the acetylation level of lysine residues in histones to regulate the gene transcription. Several clinical HDAC inhibitors had been examined as LRAs, which induced HIV activation in vitro and in vivo. Here we report the discovery of a series of selective and potent class I HDAC inhibitors based on aryl ketones as a zinc binding group, which reversed HIV latency using a Jurkat model of HIV latency in 2C4 cells. The SAR led to the discovery of a highly selective class I HDAC inhibitor 10 with excellent potency. HDACi 10 induces the HIV gag P24 protein in patient latent CD4(+) T cells.

Bruton's tyrosine kinase (BTK) is a Tec family kinase with a well-defined role in the B cell receptor (BCR) pathway. It has become an attractive kinase target for selective B cell inhibition, and for the treatment of B cell related diseases. Many BTK inhibitors have been discovered for the treatment of cancer and rheumatoid arthritis, including a series of BTK inhibitors based on 8-amino-imidazo[1,5-a]pyrazine we recently reported. The X-ray crystal structures of BTK with inhibitors were also published, which provided great help for the SAR design. Here we report our SAR work introducing ring constraints for the 3-position piperidine amides on the BTK inhibitors based on 8-amino-imidazo[1,5-a]pyrazine. This modification improved the potency in BTK inhibitions, as well as the PK profile and the off-target selectivity. The dose-dependent efficacy of two BTK inhibitors was observed in the rat collagen induced arthritis (CIA) model.

[Image: see text] The emergence and evolution of new immunological cancer therapies has sparked a rapidly growing interest in discovering novel pathways to treat cancer. Toward this aim, a novel series of pyrrolidine derivatives (compound 5) were identified as potent inhibitors of ERK1/2 with excellent kinase selectivity and dual mechanism of action but suffered from poor pharmacokinetics (PK). The challenge of PK was overcome by the discovery of a novel 3(S)-thiomethyl pyrrolidine analog 7. Lead optimization through focused structure–activity relationship led to the discovery of a clinical candidate MK-8353 suitable for twice daily oral dosing as a potential new cancer therapeutic.

We report further expansion of the structure activity relationship (SAR) on the triaryl bis sulfone class of compounds (I), which are potent CB2 receptor ligands with excellent selectivity over the CB1 receptor. This study was extended to B ring changes, followed by simultaneous optimization of the A-, B-, and C-rings. Compound 42 has excellent CB2 potency, selectivity and rat exposure.

The triaryl bis-sulfone 1 was modified by converting the aryl A-ring to a piperidine ring. The piperidine ring was further elaborated to a spirocyclopropyl piperidine moiety. The effect on CB2 binding potency, rat calcium channel affinity, and CYP 2C9 inhibition is described.

Knife cuts ventral or medial to the striatum were used to interrupt some of the principal connections of this structure. All of the cuts depleted striatal dopamine and produced aphagia and adipsia but there was no indication that the two classes of effects were always correlated. Cuts medial to the striatum produced the most severe DA depletions, persistent aphagia and adipsia, and the full complement of deficits in responding to glucoprivic and hydrational challenges that characterize rats that have recovered from lateral hypothalamic lesions. Cuts ventral to posterior portions of the striatum produced comparable periods of aphagia and adipsia (but few of the persisting impairments in responsiveness to regulatory challenges) even though their effect on striatal DA was relatively small (the average depletion was 51% compared to 89% for rats with cuts medial to the striatum). A second group of rats with cuts below more anterior aspects of the striatum sustained severe DA depletions (70%) but only very brief periods of aphagia and adipsia and only slight deficits in responding to osmotic challenges. The effects of the DA depleting cuts were compared with the behavioral consequences of coronal cuts in the midbrain tegmentum which selectively depleted hypothalamic norepinephrine. These cuts did not produce reliable effects on either food or water intake but abolished the normal feeding response to 2-deoxy-d-glucose without affecting the response to insulin. A correlational analysis of the biochemical and behavioral results of our cuts indicated a significant positive relationship between drinking in response to cellular thirst stimuli and hypothalamic NE as well as striatal DA. The postoperative body weights of our experimental animals were positively correlated with striatal dopamine and negatively related to hypothalamic norepinephrine.

Parasagittal knife cuts along the lateral border of the diencephalon (PS), coronal cuts accross the lateral (LMFB) or medial (MMFB) components of the medial forebrain bundle reproduce most of the persisting deficits in responding to glucoprivic and hydrational challenges that characterize rats with lateral hypothalamic lesions or intracranial injections of 6-hydroxydopamine (60HDA). Each of these cuts produced a different pattern of regulatory deficits, suggesting that individual components of the LH syndrome may be mediated by different neural substrates. This interpretation is supported by the results of our correlational analysis of the relationships between specific behavioral and biochemical effects of our cuts. For example, feeding responses to insulin were reliably correlated with striatal DA concentrations but feeding responses to 2-deoxy-d-glucose (2DG) were not. Water intake during periods of food deprivation was reliably correlated with striatal DA but water intake after an experimental osmotic challenge was not. Only one of the common persisting deficits (impaired feeding response to peripheral injections of insulin) was positively correlated with the duration of aphagia and adipsia.

Knife cuts were made that preferentially interrupted (a) the nigrostriatal pathway; (b) pallidofugal projections to the lower brainstem; (c) caudate-pallidal interconnections; and (d) fibers entering or leaving the striatum ventrally. The effects of these cuts on conditioned (shuttle box) avoidance, passive avoidance, swimming escape, sucrose-rewarded alley running, locomotor activity, and various measures of sensory-motor function were examined. The norepinephrine, dopamine and serotonin content of the striatum, residual forebrain and hypothalamus were determined following the completion of behavioral testing. The pattern of results suggests that striatal functions which are significantly influenced by several afferent and efferent connections are essential for the acquisition and, perhaps, execution of complex behavior in appetitive as well as aversive test paradigms. A special role for the dopaminergic afferents to the striatum was not established in these tests.

Aphagia and adipsia of equivalent duration were produced by knife cuts along the lateral border of the hypothalamus (PH cuts), or the medial surface of the globus pallidus (MP cuts) in male albino rats. Striatal dopamine (DA) was reduced by 75% in animals with PH cuts but only 50% by MP cuts. Hypothalamic norepinephrine was reduced 25% by PH cuts and was unaffected by MP cuts. Aphagia and adipsia were positively correlated with DA depletions only in rats with PH cuts. Presurgical catecholamine depletions produced by chronic injections of alpha-methyl-p-tyrosine did not alter the duration of aphagia or adipsia resulting from these knife cuts. However, following recovery of ingestive behavior, rats with PH and MP cuts were supersensitive to the anorexic effects of the dopamine-beta-hydroxylase inhibitor, diethyldithiocarbamate. Exaggerated anorexia was also observed after DA blockade by haloperidol or alpha-adrenergic blockade by phenoxybenzamine. The most pronounced effects of catecholamine blockade were observed in rats with PH cuts.