ABSTRACT
Rapadocin is a novel rapamycin-inspired polyketide-tetrapeptide hybrid macrocycle that possesses highly potent and isoform-specific inhibitory activity against the human equilibrative nucleoside transporter 1 (hENT1). Rapadocin contains an epimerizable chiral center in phenylglycine and an olefin group, and can thus exist as a mixture of four stereoisomers. Herein, we report the first total synthesis of the four stereoisomers of rapadocin using two different synthetic strategies and the assignment of their structures. The inhibitory activity of each of the four synthetic isomers on both hENT1 and hENT2 was determined. It was found that the stereochemistry of phenylglycine played a more dominant role than the configuration of the olefin in the activity of rapadocin. These findings will guide the future design and development of rapadocin analogs as new modulators of adenosine signaling.
ABSTRACT
Rapamycin and FK506 are macrocyclic natural products with an extraordinary mode of action, in which they form binary complexes with FK506-binding protein (FKBP) through a shared FKBP-binding domain before forming ternary complexes with their respective targets, mechanistic target of rapamycin (mTOR) and calcineurin, respectively. Inspired by this, we sought to build a rapamycin-like macromolecule library to target new cellular proteins by replacing the effector domain of rapamycin with a combinatorial library of oligopeptides. We developed a robust macrocyclization method using ring-closing metathesis and synthesized a 45,000-compound library of hybrid macrocycles (named rapafucins) using optimized FKBP-binding domains. Screening of the rapafucin library in human cells led to the discovery of rapadocin, an inhibitor of nucleoside uptake. Rapadocin is a potent, isoform-specific and FKBP-dependent inhibitor of the equilibrative nucleoside transporter 1 and is efficacious in an animal model of kidney ischaemia reperfusion injury. Together, these results demonstrate that rapafucins are a new class of chemical probes and drug leads that can expand the repertoire of protein targets well beyond mTOR and calcineurin.
Subject(s)
Drug Discovery/methods , Macrolides/chemistry , Macrolides/metabolism , Protective Agents/chemistry , Protective Agents/metabolism , Acute Kidney Injury/metabolism , Acute Kidney Injury/prevention & control , Animals , Cell Line , Human Umbilical Vein Endothelial Cells , Humans , Mice , Proteome/metabolism , Reperfusion Injury/metabolism , Reperfusion Injury/prevention & control , Sirolimus/chemistry , Sirolimus/metabolism , Swine , TOR Serine-Threonine Kinases/chemistry , TOR Serine-Threonine Kinases/metabolism , Tacrolimus/chemistry , Tacrolimus/metabolism , Tacrolimus Binding Proteins/chemistry , Tacrolimus Binding Proteins/metabolismABSTRACT
A series of oxamyl dipeptides were optimized for pan caspase inhibition, anti-apoptotic cellular activity and in vivo efficacy. This structure-activity relationship study focused on the P4 oxamides and warhead moieties. Primarily on the basis of in vitro data, inhibitors were selected for study in a murine model of alpha-Fas-induced liver injury. IDN-6556 (1) was further profiled in additional in vivo models and pharmacokinetic studies. This first-in-class caspase inhibitor is now the subject of two Phase II clinical trials, evaluating its safety and efficacy for use in liver disease.
Subject(s)
Caspase Inhibitors , Liver Diseases/drug therapy , Pentanoic Acids/chemical synthesis , Adult , Alanine Transaminase/blood , Animals , Apoptosis/drug effects , Aspartate Aminotransferases/blood , Biological Availability , Caspase 3 , Cholestasis/drug therapy , Cholestasis/pathology , Clinical Trials, Phase I as Topic , Half-Life , Hepatitis C, Chronic/drug therapy , Hepatocytes/drug effects , Hepatocytes/pathology , Humans , Jurkat Cells , Liver/drug effects , Liver/pathology , Liver Diseases/enzymology , Liver Diseases/etiology , Mice , Pentanoic Acids/chemistry , Pentanoic Acids/pharmacology , Rats , Structure-Activity RelationshipABSTRACT
Various heterocyclic hetero-methyl ketones of the 1-naphthyloxyacetyl-Val-Asp backbone have been prepared. A study of their structure-activity relationship (SAR) related to caspase-1, -3, -6, and -8 is reported. Their efficacy in a cellular model of cell death is also discussed. Potent broad-spectrum caspase inhibitors have been identified.
Subject(s)
Caspase Inhibitors , Cell Death/drug effects , Cysteine Proteinase Inhibitors/pharmacology , Heterocyclic Compounds/pharmacology , Ketones/pharmacology , Animals , Aspartic Acid/chemistry , Cells, Cultured , Heterocyclic Compounds/chemical synthesis , Ketones/chemical synthesis , Mice , Models, Biological , Naphthols/chemistry , Structure-Activity Relationship , Valine/chemistryABSTRACT
Structural modifications were made to a previously described acyl dipeptide caspase inhibitor, leading to the oxamyl dipeptide series. Subsequent SAR studies directed toward the warhead, P2, and P4 regions of this novel peptidomimetic are described herein.
Subject(s)
Caspase Inhibitors , Dipeptides/chemical synthesis , Dipeptides/pharmacology , Apoptosis/drug effects , Carbamates , Cell Line , Humans , Inhibitory Concentration 50 , Kinetics , Neurodegenerative Diseases/drug therapy , Stroke/drug therapy , Structure-Activity RelationshipABSTRACT
Various aryloxy methyl ketones of the 1-naphthyloxyacetyl-Val-Asp backbone have been prepared. A systematic study of their structure-activity relationship (SAR) related to caspases 1, 3, 6, and 8 is reported. Highly potent irreversible broad-spectrum caspase inhibitors have been identified. Their efficacy in cellular models of cell death and inflammation are also discussed.
Subject(s)
Caspase Inhibitors , Cysteine Proteinase Inhibitors/chemistry , Cysteine Proteinase Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
A new structural class of broad spectrum caspase inhibitors was optimized for its activity against caspases 1, 3, 6, 7, and 8. The most potent compound had low nanomolar broad spectrum activity, in particular, single digit nanomolar inhibitory activity against caspase 8.
