Cobalt-Catalyzed Z to E Isomerization of Alkenes: An Approach to (E)-ß-Substituted Styrenes.

An efficient cobalt-catalyzed Z to E isomerization of ß-substituted styrenes using the amido-diphosphine ligand was developed, delivering the (E)-isomers with good functional tolerance and high stereoselectivity. The reaction could be scaled up to gram-scale with a catalyst loading of 0.1 mol %, using a mixture of (Z)- and (E)-alkene as the starting material. Preliminary mechanistic studies indicated that cobalt(I)-hydride and a benzylic-cobalt species were probably involved in the reaction, as supported by experiments and DFT calculations.

Design, synthesis and biological evaluation of novel 2-sulfonylindoles as potential anti-inflammatory therapeutic agents for treatment of acute lung injury.

Acute lung injury (ALI) is primarily driven by inflammation that severely impacts lung function. Novel 2-sulfonylindoles were recently shown to exhibit anti-inflammatory activity through the inhibition of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production. Here, we synthesized 31 compounds which contained 2-sulfonylindole structure. The compounds 8a, 9g, 9h and 9k exhibited dose-dependent anti-inflammatory activity in vitro. Structural-activity relationship analysis revealed that the introduction of sulfonyl group in indole nucleus may be successful to obtain new anti-inflammatory structures and leads. The compounds 9h and 9k also decreased liposaccharide (LPS)-induced IL-6, IL-1ß and vascular cell adhesion molecule-1 (VCAM-1) mRNA expression, both in vitro and in an in vivo model of ALI. Furthermore, the compounds 9h and 9k at a high dose (20 mg/kg) significantly protected against LPS-induced ALI in mice. These results show that compounds 9h and 9k could be a promising lead structure for the treatment of ALI.

Design, Synthesis, and Structure-Activity Relationship Analysis of Thiazolo[3,2-a]pyrimidine Derivatives with Anti-inflammatory Activity in Acute Lung Injury.

Acute lung injury (ALI) has a high lethality rate, and interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) contribute most to tissue deterioration in cases of ALI. In this study, we designed and synthesized a new series of thiazolo[3,2-a]pyrimidine derivatives based on a previously identified lead compound, and we evaluated their anti-inflammatory activities. Structure-activity relationship studies led to the discovery of two highly potent inhibitors. The two promising compounds were found to inhibit lipopolysaccharide (LPS)-induced IL-6 and TNF-α release in a dose-dependent manner in mouse primary peritoneal macrophages (MPMs). Furthermore, administration of these compounds resulted in lung histopathological improvements and attenuated LPS-induced ALI in vivo. Taken together, these data indicate that these novel thiazolo[3,2-a]pyrimidine derivatives could be developed as candidate drugs for the treatment of ALI.

Structure-based discovery of LpxC inhibitors.

The emergence and spread of multidrug-resistant (MDR) Gram negative bacteria presents a serious threat for public health. Novel antimicrobials that could overcome the resistance problems are urgently needed. UDP-3-O-(R-3-hydroxymyristol)-N-acetylglucosamine deacetylase (LpxC) is a cytosolic zinc-based deacetylase that catalyzes the first committed step in the biosynthesis of lipid A, which is essential for the survival of Gram-negative bacteria. Our efforts toward the discovery of novel LpxC inhibitors are presented herein.

Design, Synthesis, and Structure-Activity Relationship Study of Novel Indole-2-carboxamide Derivatives as Anti-inflammatory Agents for the Treatment of Sepsis.

Sepsis is characterized by a systemic inflammatory response syndrome. Derivatives of indole have been reported to exhibit diverse biological activities. This study reports on the design and synthesis of a new series of indole-2-carboxamide derivatives, which are screened for their anti-inflammatory activities in RAW 264.7 macrophages. A majority of these derivatives effectively inhibited lipopolysaccharides (LPS)-induced expression of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Preliminary structure-activity relationship analysis was also conducted. The results indicate that the most promising compounds in the prepared series were 14f and 14g. They were found to effectively reduce LPS-induced pulmonary inflammation and overexpression of a series of inflammatory mediators. Furthermore, in vivo administration of 14f and 14g resulted in remarkable lung histopathological improvements in mice without toxicity in organs. Taken together, these data indicate that the newly discovered indole-2-carboxamide derivatives could be particularly useful for further treatment in inflammatory diseases.

From bacterial genomes to novel antibacterial agents: discovery, characterization, and antibacterial activity of compounds that bind to HI0065 (YjeE) from Haemophilus influenzae.

As part of a fully integrated and comprehensive strategy to discover novel antibacterial agents, NMR- and mass spectrometry-based affinity selection screens were performed to identify compounds that bind to protein targets uniquely found in bacteria and encoded by genes essential for microbial viability. A biphenyl acid lead series emerged from an NMR-based screen with the Haemophilus influenzae protein HI0065, a member of a family of probable ATP-binding proteins found exclusively in eubacteria. The structure-activity relationships developed around the NMR-derived biphenyl acid lead were consistent with on-target antibacterial activity as the Staphylococcus aureus antibacterial activity of the series correlated extremely well with binding affinity to HI0065, while the correlation of binding affinity with B-cell cytotoxicity was relatively poor. Although further studies are needed to conclusively establish the mode of action of the biphenyl series, these compounds represent novel leads that can serve as the basis for the development of novel antibacterial agents that appear to work via an unprecedented mechanism of action. Overall, these results support the genomics-driven hypothesis that targeting bacterial essential gene products that are not present in eukaryotic cells can identify novel antibacterial agents.

Structure-based optimization of MurF inhibitors.

The D-Ala-D-Ala adding enzyme (MurF) from Streptococcus pneumoniae catalyzes the ATP-dependent formation of the UDP-MurNAc-pentapeptide, a critical component of the bacterial cell wall. MurF is a potential target for antibacterial design because it is unique to bacteria and performs an essential non-redundant function in the bacterial cell. The recent discovery and subsequent cocrystal structure determination of MurF in complex with a new class of inhibitors served as a catalyst to begin a medicinal chemistry program aimed at improving their potency. We report here a multidisciplinary approach to this effort that allowed for rapid generation of cocrystal structures, thereby providing the crystallographic information critical for driving the inhibitor optimization process. This effort resulted in the discovery of low-nanomolar inhibitors of this bacterial enzyme.

Structure-based characterization and optimization of novel hydrophobic binding interactions in a series of pyrrolidine influenza neuraminidase inhibitors.

The structure-activity relationship (SAR) of a novel hydrophobic binding interaction within a subsite of the influenza neuraminidase (NA) active site was characterized and optimized for a series of trisubstituted pyrrolidine inhibitors modified at the 4-position. Previously, potent inhibitors have targeted this subsite with hydrophilic substituents such as amines and guanidines. Inhibitor-bound crystal structures revealed that hydrophobic substituents with sp(2) hybridization could achieve optimal interactions by virtue of a low-energy binding conformation and favorable pi-stacking interactions with the residue Glu119. From a lead methyl ester, investigation of five-membered heteroaromatic substituents at C-4 produced a 3-pyrazolyl analogue that improved activity by making a targeted hydrogen bond with Trp178. The SAR of substituted vinyl substituents at C-4 produced a Z-propenyl analogue with improved activity over the lead methyl ester. The C-1 ethyl ester prodrugs of the substituted C-4 vinyl analogues gave compounds with excellent oral bioavailability (F > 60%) when dosed in rat.

Synthesis and antibacterial activity of 5-methoxy- and 5-hydroxy-6-fluoro-1,8-naphthyridone-3-carboxylic acid derivatives.

A series of 5-methoxy- and 5-hydroxy-6-fluoro-1,8-naphthyridone-3-carboxylic acid derivatives were prepared and evaluated for cell-free bacterial protein synthesis inhibition and whole cell antibacterial activity. When compared to the analogous 5-hydrogen compounds, the presence of the 5-OH group negatively affects biochemical potency. However, a tolerance of the 5-methoxy group is indicated. Only moderate whole cell antibacterial activity is seen, but this could be due to poor cellular penetration. Because only a few 7-position variants were made for this study, further investigation into this novel series combining a broader range of 7-amino derivatives with these 5-position modifications is warranted.

Synthesis and biological evaluation of 6,7-disubstituted 4-aminopyrido[2,3-d]pyrimidines as adenosine kinase inhibitors.

The synthesis and structure-activity relationship of a series of 6,7-disubstituted 4-aminopyrido[2,3-d]pyrimidines as novel non-nucleoside adenosine kinase inhibitors is described. A variety of substituents, primarily aryl, at the C6 and C7 positions of the pyridopyrimidine core were found to yield analogues that are potent inhibitors of adenosine kinase. In contrast to the 5,7-disubstituted and 5,6,7-trisubstituted pyridopyrimidine series, these analogues exhibited only modest potency to inhibit AK in intact cells.

Novel inhibitors of bacterial protein synthesis: structure-activity relationships for 1,8-naphthyridine derivatives incorporating position 3 and 4 variants.

Structure-activity relationships for a recently discovered novel ribosome inhibitor (NRI) class of antibacterials were investigated. Preliminary efforts to optimize protein synthesis inhibitory activity of the series through modification of positions 3 and 4 of the naphthyridone lead template resulted in the identification of several biochemically potent analogues. A lack of corresponding whole cell antibacterial activity is thought to be a consequence of poor cellular penetration as evidenced by the enhancement of activity observed for a lead analogue tested in the presence of a cell permeabilizing agent.

5,6,7-trisubstituted 4-aminopyrido[2,3-d]pyrimidines as novel inhibitors of adenosine kinase.

The synthesis and structure-activity relationship of a series of 5,6,7-trisubstituted 4-aminopyrido[2,3-d]pyrimidines as novel nonnucleoside adenosine kinase inhibitors is described. A variety of alkyl, aryl, and heteroaryl substituents were found to be tolerated at the C5, C6, and C7 positions of the pyridopyrimidine core. These studies have led to the identification of analogues that are potent inhibitors of adenosine kinase with in vivo analgesic activity.

Influenza neuraminidase inhibitors: structure-based design of a novel inhibitor series.

Combinatorial and structure-based medicinal chemistry strategies were used together to advance a lead compound with an activity of K(i) = 58 microM via a potency enhancement of >70 000-fold to an analogue with an activity of K(i) = 0.8 nM against influenza neuraminidase (A/Tokyo/67). Lead optimization was initiated using molecular modeling and combinatorial chemistry. Protein crystal structures revealed that inconsistent structure-activity relationship (SAR) data resulted from different binding orientations of the inhibitor core five-membered rings from one series to another. Binding modes for a series of compounds showed up to a 180 degrees variation in orientation of the five-membered ring within the active site. Potent analogues were only achieved with chemical series that were observed to bind in the same orientation and yielded consistent SAR. In one series, consistent binding was obtained by an unprecedented occupation of a negatively charged binding pocket by a neutral methyl ester unit. The structural rationale for this novel SAR variation, based on protein crystallographic data, is given.