Herein we present the outcome of a high throughput screening (HTS) campaign-based strategy for the rapid identification and optimization of selective and general chemotypes for both kappa (κ) opioid receptor (KOR) activation and inhibition. In this program, we have developed potent antagonists (IC50 < 120 nM) or agonists of high binding affinity (Ki < 3 nM). In contrast to many important KOR ligands, the compounds presented here are highly modular, readily synthesized and, in most cases, achiral. The four new chemotypes hold promise for further development into chemical tools for studying the KOR or as potential therapeutic lead candidates.

Herein we report that N-alkyl-octahydroisoquinolin-1-one-8-carboxamides are a novel class of readily-synthesized, selective ϰ-opioid receptor (KOR) ligands. A striking feature of this class of compounds is the absence of any basic nitrogen atoms. Many of these compounds have demonstrated exclusive affinity for the KOR over not only the δ-opioid receptor (DOR) and the μ-opioid receptor (MOR), but 38 other GPCR targets as well. The general binding affinity of this class of compounds for the KOR combined with a streamlined route for analog synthesis provide strong motivation for pursuing this interesting new scaffold as a basis toward new probes targeting the KOR.

Emerging resistance to existing antibiotics is an inevitable matter of concern in the treatment of bacterial infection. Naturally occurring unique class of natural antibiotic, platensimycin, a secondary metabolite from Streptomyces platensis, is an excellent breakthrough in recent antibiotic research with unique structural pattern and significant antibacterial activity. β-Ketoacyl-(acyl-carrier-protein (ACP)) synthase (FabF) whose Gram-positive bacteria need to biosynthesize cell membranes is the target of inhibition of platensimycin. So, isolation, retrosynthetic analysis, synthesis of platensimycin, and analogues of platensimycin synthesized till today are the objectives of this review which may be helpful to further investigate and to reveal untouched area on this molecule and to obtain a potential antibacterial lead with enhanced significant antibacterial activity.

The target of this study, the PfM18 aspartyl aminopeptidase (PfM18AAP), is the only AAP present in the genome of the malaria parasite Plasmodium falciparum. PfM18AAP is a metallo-exopeptidase that exclusively cleaves N-terminal acidic amino acids glutamate and aspartate. It is expressed in parasite cytoplasm and may function in concert with other aminopeptidases in protein degradation, of, for example, hemoglobin. Previous antisense knockdown experiments identified a lethal phenotype associated with PfM18AAP suggesting that it is a valid target for new anti-malaria therapies. To identify inhibitors of PfM18AAP function, a fluorescence enzymatic assay was developed using recombinant PfM18AAP enzyme and a fluorogenic peptide substrate (H-Glu-NHMec). This was screened against the Molecular Libraries Probe Production Centers Network (MLPCN) collection of ~292,000 compounds (the Molecular Libraries Small Molecule Repository (MLSMR)). A Cathepsin L1 (CTSL1) enzyme-based assay was developed and used as a counterscreen to identify compounds with nonspecific activity. Enzymology and phenotypic assays were used to determine mechanism of action and efficacy of selective and potent compounds identified from HTS. Two structurally related compounds, CID 6852389 and CID 23724194, yield micromolar potency and are inactive in CTSL1 titration experiments (IC50 >59.6 μM). As measured by Ki assay, both compounds demonstrate micromolar non-competitive inhibition in the PfM18AAP enzyme assay. Both CID 6852389 and CID 23724194 demonstrate potency in malaria growth assays (IC50 4 μM and 1.3 μM, respectively).

A concise route to functionalized 14-membered macrolides related to erythronolide A was achieved. Key steps include the simultaneous formation of bis[allenic] substrates, efficient macrolactonization, highly stereoselective oxidation to the corresponding bis[spirodiepoxide], and nucleophilic spirodiepoxide opening. The structure and reactivity of these macrolides, and the strategy that led to their evaluation, are discussed.