In medicinal chemistry, purification and characterization of organic compounds is an ever-growing challenge, with an increasing number of compounds being synthesized at a decreased scale of preparation. In response to this trend, we developed a parallel medicinal chemistry (PMC)-tailored platform, coupling automated purification to mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR) on a range of synthetic scales (similar to 3.0-75.0 mu mol). Here, the generation and acquisition of 1.7 mm NMR samples is fully integrated into a high-throughput automated workflow, processing 36 000 compounds yearly. Utilizing dead volume, which is inaccessible in conventional liquid handling, NMR samples are generated on as little as 10 mu g without consuming material prioritized for biological assays. As miniaturized PMC synthesis becomes the industry standard, we can now obtain quality NMR spectra from limited material. Paired with automated structure verification, this platform has the potential to allow NMR to become as important for high-throughput analysis as ultrahigh performance liquid chromatography (UPLC)-MS.

To gain further insight into the conformational properties of small cyclic peptides that bind to the G-protein coupled receptor C5aR1, we report here for the first time the elucidation of three peptide solution conformations using residual dipolar couplings and NMR temperature coefficients. Each of these peptides varies by at least one amino acid, adopts a different intramolecular hydrogen bonding pattern, and has a different solution conformation. The solution conformations were used in combination with a homology structure of C5aR1 as a design template for increasing the potency of peptide leads for the C5a receptor. This study provides a framework for using RDC solution conformations to guide the design of peptide mimetics that emulate the target bound state in solution to minimize the strain energy of the bound conformation and improve potency of the peptide for the target.

This annual review is the sixth of its kind since 2016 (see references). Our objective is to explore and share articles which we deem influential and significant in the field of biotransformation and bioactivation. These fields are constantly evolving with new molecular structures and discoveries of corresponding pathways for metabolism that impact relevant drug development with respect to efficacy and safety. Based on the selected articles, we created three sections: (1) drug design, (2) metabolites and drug metabolizing enzymes, and (3) bioactivation and safety (Table 1). Unlike in years past, more biotransformation experts have joined and contributed to this effort while striving to maintain a balance of authors from academic and industry settings.[Table: see text].

An experimental approach is described for late-stage lead diversification of frontrunner drug candidates using nanomole-scale amounts of lead compounds for structure-activity relationship development. The process utilizes C-H bond activation methods to explore chemical space by transforming candidates into newly functionalized leads. A key to success is the utilization of microcryoprobe nuclear magnetic resonance (NMR) spectroscopy, which permits the use of low amounts of lead compounds (1-5 μmol). The approach delivers multiple analogues from a single lead at nanomole-scale amounts as DMSO-d6 stock solutions with a known structure and concentration for in vitro pharmacology and absorption, distribution, metabolism, and excretion testing. To demonstrate the feasibility of this approach, we have used the antihistamine agent loratadine (1). Twenty-six analogues of loratadine were isolated and fully characterized by NMR. Informative SAR analogues were identified, which display potent affinity for the human histamine H1 receptor and improved metabolic stability.

C5a is a terminal product of the complement cascade that activates and attracts inflammatory cells including granulocytes, mast cells and macrophages via a specific GPCR, the C5a receptor (C5aR). Inhibition of C5a/C5aR interaction has been shown to be efficacious in several animal models of autoimmune diseases, including RA, SLE and asthma. This account reports the discovery of a new class of C5aR antagonists through high-throughput screening. The lead compounds in this series are selective and block C5a binding, C5a-promoted calcium flux in human neutrophils with nanomolar potency.

B-Raf kinase plays a critical role in the Raf-MEK-ERK signaling pathway and inhibitors of B-Raf could be used in the treatment of melanomas, colorectal cancer, and other Ras related human cancers. We have identified novel small molecule pyrazolo[1,5-a]pyrimidine derivatives as B-Raf kinase inhibitors. Structure-activity relationship was generated for various regions of the scaffold to improve the biochemical profile.

Our continued effort towards optimization of the pyrazolo[1,5-a]pyrimidine scaffold as B-Raf kinase inhibitors is described. Structure guided design was utilized to introduce kinase hinge region interacting groups in the 2-position of the scaffold. This strategy led to the identification of lead compound 9 with enhanced enzyme and cellular potency, while maintaining good selectivity over a number of kinases.

As part of our research effort to discover B-Raf kinase inhibitors, we prepared a series of C-3 substituted N-(3-(pyrazolo[1,5-a]pyrimidin-7-yl)phenyl)-3-(trifluoromethyl)benzamides. X-ray crystallography studies revealed that one of the more potent inhibitors (10n) bound to B-Raf kinase without forming a hinge-binding hydrogen bond. With basic amine residues appended to C-3 aryl residues, cellular activity and solubility were enhanced over previously described compounds of this class.

Through high throughput screening, substituted proline sulfonamide 6 was identified as HCV NS5b RNA-dependent RNA polymerase inhibitor. Optimization of various regions of the lead molecule resulted in compounds that displayed good potency and selectivity. The crystal structure of 6 and NS5b polymerase complex confirmed the binding near the active site region. The optimization approach and SAR are discussed in detail.

A novel class of HCV NS5B RNA dependent RNA polymerase inhibitors containing 2,3,4,9-tetrahydro-1H-carbazole and 1,2,3,4-tetrahydro-cyclopenta[b]indole scaffolds were designed and synthesized. Optimization of the aromatic region showed preference for 5,8-disubstitution pattern in both the scaffolds examined while favoring the n-propyl moiety for the C-1 position. 1,2,3,4-tetrahydro-cyclopenta[b]indole scaffold was slightly more potent than the corresponding 2,3,4,9-tetrahydro-1H-carbazole and analogue 36 displayed an IC50 of 550 nM against HCV NS5B enzyme.

A novel class of HCV NS5B RNA dependent RNA polymerase inhibitors containing 3,4-dihydro-1H-[1]-benzothieno[2,3-c]pyran and 3,4-dihydro-1H-pyrano[3,4-b]benzofuran scaffolds were designed and synthesized. Optimization of the alkyl substituent in the pyran ring showed preference for an n-propyl group, while 5,8-disubstitution pattern is preferred for the aromatic region. Analog 19 displayed potent activity with an IC(50) of 50 nM against HCV NS5B enzyme and was selective over a panel of polymerases.

The synthesis and structure-activity studies of a series of 6-substituted-4-anilino-[1,7]-naphthyridine-3-carbonitriles as inhibitors of Tpl2 kinase are described. The early exploratory work described here may lead to the discovery of compounds with significant therapeutic potential for treating rheumatoid arthritis and other inflammatory diseases.

L'invention concerne un procede de traitement, de prevention ou d'inhibition d'une infection virale d'un mammifere par l'hepatite C, qui consiste a mettre le mammifere en contact avec une quantite efficace d'un compose correspondant a la formule (I), les substitutions dans R1 - R13, m et Y etant definis dans la specification.