Exploration of the P1 residue in 3CL protease inhibitors leading to the discovery of a 2-tetrahydrofuran P1 replacement

The virally encoded 3C-like protease (3CLpro) is a well-validated drug target for the inhibition of coronaviruses including Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). Most inhibitors of 3CLpro are peptidomimetic, with a γ-lactam in place of Gln at the P1 position of the pseudopeptide chain. An effort was pursued to identify a viable alternative to the γ-lactam P1 mimetic which would improve physicochemical properties while retaining affinity for the target. Discovery of a 2-tetrahydrofuran as a suitable P1 replacement that is a potent enzymatic inhibitor of 3CLpro in SARS-CoV-2 virus is described herein.

EZH2 inhibition as a therapeutic strategy for lymphoma with EZH2-activating mutations

In eukaryotes, post-translational modification of histones is critical for regulation of chromatin structure and gene expression. EZH2 is the catalytic subunit of the polycomb repressive complex 2 (PRC2) and is involved in repressing gene expression through methylation of histone H3 on lysine 27 (H3K27). EZH2 overexpression is implicated in tumorigenesis and correlates with poor prognosis in several tumour types. Additionally, somatic heterozygous mutations of Y641 and A677 residues within the catalytic SET domain of EZH2 occur in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma. The Y641 residue is the most frequently mutated residue, with up to 22% of germinal centre B-cell DLBCL and follicular lymphoma harbouring mutations at this site. These lymphomas have increased H3K27 tri-methylation (H3K27me3) owing to altered substrate preferences of the mutant enzymes. However, it is unknown whether specific, direct inhibition of EZH2 methyltransferase activity will be effective in treating EZH2 mutant lymphomas. Here we demonstrate that GSK126, a potent, highly selective, S-adenosyl-methionine-competitive, small-molecule inhibitor of EZH2 methyltransferase activity, decreases global H3K27me3 levels and reactivates silenced PRC2 target genes. GSK126 effectively inhibits the proliferation of EZH2 mutant DLBCL cell lines and markedly inhibits the growth of EZH2 mutant DLBCL xenografts in mice. Together, these data demonstrate that pharmacological inhibition of EZH2 activity may provide a promising treatment for EZH2 mutant lymphoma.

Abstract 2939: Discovery and synthesis of highly potent and selective small molecule inhibitors of the histone methyltransferase EZH2

The histone methyltransferases are a group of enzymes which catalyze the transfer of a methyl group from the co-factor S-Adenosylmethionine (SAM) to the lysine and arginine residues of histone tails. This post-translational modification is a key event in maintaining gene expression patterns. In recent years, the relationships between aberrant histone methylation patterns and cancer progression have been recognized. These developments, along with an improved understanding of the underlying structural biology, have made histone methyltransferases highly attractive targets for therapeutic intervention. The histone lysine methyltransferase EZH2 (Enhancer of Zeste Homolog 2) is frequently over-expressed in a wide variety of cancerous tissues. There is a strong correlation between overexpression of EZH2 and aberrant transcriptional signaling in cells, ultimately resulting in poor clinical prognosis. Inhibition of EZH2 is expected to alter transcriptional expression and ultimately lead to an improved clinical outcome. This presentation will describe medicinal chemistry efforts in the development of highly potent and selective small molecule inhibitors of EZH2. The synthesis, SAR, and identification of a clinical candidate will be discussed.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2939. doi:1538-7445.AM2012-2939

An investigation of imidazole and oxazole syntheses using aryl-substituted TosMIC reagents

This article describes efficient and mild protocols for preparing polysubstituted imidazoles in a single pot from aryl-substituted tosylmethyl isocyanide (TosMIC) reagents and imines generated in situ. Traditional imine-forming reactions employing virtually any aldehyde and amine followed by addition of the TosMIC reagent delivers 1,4,5-trisubstituted imidazoles with predictable regiochemistry. Employing chiral amines and aldehydes, particularly those derived from alpha-amino acids, affords imidazoles with asymmetric centers appended to N-1 or C-5 with excellent retention of chiral purity. 1,4-Disubstituted imidazoles are also readily prepared by a simple variant of the above procedure. Selecting glyoxylic acid as the aldehyde component of this procedure leads to intermediates such as 48, which readily undergo decarboxylation and elimination of the tosyl moiety to deliver 1,4-disubstituted imidazoles in high yields. Alternatively, using NH(4)OH as the amine component in conjunction with a variety of aldehydes delivers 4, 5-disubstituted imidazoles in moderate to good yields in a single pot while avoiding the need for protecting groups. Finally, the facile preparation of mono- and disubstituted oxazoles from these TosMIC reagents and aldehydes is described.

Videographic Hirschberg measurement of simulated strabismic deviations

PURPOSE

To demonstrate the potential use of subpixel image processing methods to perform automated Hirschberg measurements of strabismic deviations using relatively inexpensive personal computer hardware; to determine if the method might allow screening for strabismus using full-face video images obtained from a distance of 1 meter.

METHODS

Strabismic deviations (< 25 prism diopters) were simulated by means of induced asymmetric fixation. A ring of coaxial infrared light-emitting diodes (LED) were used to generate first Purkinje reflexes. Computerized image analysis with subpixel processing was used to measure the locations of the first Purkinje reflexes and pupil centers of video images of 10 normal subjects, following the technique of the clinical Hirschberg test. The apparent strabismic deviation was calculated from the relative asymmetry of the center of the corneal reflex ring to the pupil center in each eye.

RESULTS

In 10 normal subjects, there was a statistically significant linear correlation of Hirschberg horizontal reflex deviation with asymmetric fixation pseudo-esotropia (0.85 > or = r2 > or = 0.99, P < 0.05).

CONCLUSIONS

The Hirschberg test is used manually to detect strabismus in infants and children but requires a highly skilled examiner. The image processing method described here requires no operator interpretation and may make the test more applicable. The results suggest that this technology may be appropriate for a screening instrument.

Epidemiological and clinical approach to the study of candidiasis caused by Candida albicans in heroin addicts in the Paris region: analysis of 35 observations

A study of 35 cases of deep-seated Candida albicans candidiasis, affecting heroin addicts in the Paris region, revealed that the lesions observed were mainly cutaneous (88 per cent) and ocular (65 per cent), along with a number of instances of osteoarticular and pleuropulmonary attacks. The clinical and epidemiological findings indicated the possibility that Candida albicans might be transmitted through the heroin. This paper also presents the diagnostic techniques, and the novelty of the clinical picture, in which cutaneous and ocular lesions are frequently associated (57 per cent).