Prospects for Antibacterial Discovery and Development.

The rising prevalence of multidrug-resistant bacteria is an urgent health crisis that can only be countered through renewed investment in the discovery and development of antibiotics. There is no panacea for the antibacterial resistance crisis; instead, a multifaceted approach is called for. In this Perspective we make the case that, in the face of evolving clinical needs and enabling technologies, numerous validated antibacterial targets and associated lead molecules deserve a second look.

Toward Orally Absorbed Prodrugs of the Antibiotic Aztreonam. Design of Novel Prodrugs of Sulfate Containing Drugs. Part 2.

Aztreonam, first discovered in 1980, is an FDA approved, intravenous, monocyclic beta-lactam antibiotic. Aztreonam is active against Gram-negative bacteria and is still used today. The oral bioavailability of aztreonam in humans is less than 1%.

Orally Absorbed Derivatives of the β-Lactamase Inhibitor Avibactam. Design of Novel Prodrugs of Sulfate Containing Drugs.

Only one FDA-approved β-lactamase inhibitor has ever been orally available: clavulanic acid, approved in 1984. Avibactam, approved by FDA in 2015, is the first of a new class of BLIs called diazabicyclooctanes, or "DBOs". This class has much broader coverage than clavulanic acid but can only be administered by intravenous injection.

Selective reduction of peptide isothiazolidin-3-ones.

Isothiazolidinones are a rare but potentially important chemical moiety in biochemistry. We report the identification of several thiol, phosphinate, and carbon nucleophiles that form covalent adducts by addition to the sulfenamide sulfur. This reduction is selective for isothiazolidinones over similar peptide disulfides.

Aminoethylenes: a tetrahedral intermediate isostere yielding potent inhibitors of the aspartyl protease BACE-1.

A series of novel beta-site amyloid precursor protein cleaving enzyme (BACE-1) inhibitors containing an aminoethylene (AE) tetrahedral intermediate isostere were synthesized and evaluated in comparison to corresponding hydroxyethylene (HE) compounds. Enzymatic inhibitory values were similar for both isosteres, as were structure-activity relationships with respect to stereochemical preference and substituent variation (P2/P3, P1, and P2'); however, the AE compounds were markedly more potent in a cell-based assay for reduction of beta-secretase activity. The incorporation of preferred P2/P3, P1, and P2' substituents into the AE pharmacophore yielded compound 7, which possessed enzymatic and cell assay IC(50)s of 26 nM and 180 nM, respectively.

Identification of potent and novel small-molecule inhibitors of caspase-3.

The design and synthesis of a series of novel, reversible, small molecule inhibitors of caspase-3 are described.

Combinatorial modification of natural products: synthesis and in vitro analysis of derivatives of thiazole peptide antibiotic GE2270 A: A-ring modifications.

Thiazole peptide GE2270 A (1) possesses potent antimicrobial activity against many gram-positive pathogens, including methicillin resistant Staphylococcus aureus (S. aureus, MRSA; MIC(90)=0.06 microg/mL) and vancomycin resistant Enterococcus spp.

In situ assembly of enzyme inhibitors using extended tethering.

Cysteine aspartyl protease-3 (caspase-3) is a mediator of apoptosis and a therapeutic target for a wide range of diseases. Using a dynamic combinatorial technology, 'extended tethering', we identified unique nonpeptidic inhibitors for this enzyme. Extended tethering allowed the identification of ligands that bind to discrete regions of caspase-3 and also helped direct the assembly of these ligands into small-molecule inhibitors.

Identification of potent and selective small-molecule inhibitors of caspase-3 through the use of extended tethering and structure-based drug design.

The design, synthesis, and in vitro activities of a series of potent and selective small-molecule inhibitors of caspase-3 are described. From extended tethering, a salicylic acid fragment was identified as having binding affinity for the S(4) pocket of caspase-3. X-ray crystallography and molecular modeling of the initial tethering hit resulted in the synthesis of 4, which reversibly inhibited caspase-3 with a K(i) = 40 nM.

Solid-Phase Synthesis of beta-Sultams.

Solid-phase synthesis of beta-sultams amenable for construction of sulfonyl beta-lactam analogue combinatorial libraries is reported. Imine intermediates generated from polymer-immobilized amino acids and aldehydes are reacted with (chlorosulfonyl)acetates in the presence of pyridine to afford the solid-phase-tethered beta-sultam products. The latter can be released from support by acidic cleavage (TFA) or photocleavage, depending on the nature of the linker employed (acid-labile or photolabile linkers).