ABSTRACT
Studies of 17 analoges of 3 (SJA6017) in an in silico calpain model are reconciled to measured IC(50) values against ovine calpain. The studies validate the potential of the "model" and criteria established for inhibition as a tool to select structures for synthesis to test as calpain inhibitors. Using this screening methodology of virtual libraries led us to synthesize several inhibitors including macrocycle 33, which in vitro sheep eye lens culture experiments showed to substantially slow opacification.
Subject(s)
Calpain/antagonists & inhibitors , Cataract/prevention & control , Dipeptides/chemistry , Macrocyclic Compounds/chemistry , Models, Molecular , Amino Acid Sequence , Animals , Calpain/chemistry , Calpain/genetics , Catalytic Domain , Databases, Factual , Dipeptides/chemical synthesis , Dipeptides/pharmacology , Lens, Crystalline/drug effects , Lens, Crystalline/pathology , Macrocyclic Compounds/chemical synthesis , Macrocyclic Compounds/pharmacology , Molecular Sequence Data , Mutation , Protein Conformation , Sheep , Structure-Activity Relationship , Tissue Culture TechniquesABSTRACT
The design and elaboration of a series of macrocyclic templates that exhibit a propensity to adopt a beta-strand-like peptide-backbone conformation led to potent and selective inhibitors of calpain 2. Macrocycle 1 retarded calcium-induced opacification in an ovine-lens culture assay and is a lead compound for the development of a drug for cataract treatment. Cbz=carbobenzyloxy.
Subject(s)
Calpain/antagonists & inhibitors , Cysteine Proteinase Inhibitors/chemistry , Models, Molecular , Animals , Calpain/metabolism , Cataract/chemically induced , Cataract/drug therapy , Cysteine Proteinase Inhibitors/chemical synthesis , Cysteine Proteinase Inhibitors/pharmacology , Heterocyclic Compounds/chemical synthesis , Heterocyclic Compounds/chemistry , Inhibitory Concentration 50 , Lens, Crystalline/metabolism , Macrocyclic Compounds/chemical synthesis , Macrocyclic Compounds/chemistry , Macrocyclic Compounds/pharmacology , Sheep , Structure-Activity RelationshipABSTRACT
The photoswitchable N-terminal diazo and triazene-dipeptide aldehydes 8a-d, 10a,b, and 17a,b present predominantly as the (E)-isomer, which purportedly binds deep in the S3 pocket of calpain. All compounds are potent inhibitors of m-calpain, with 8b being the most active (IC50 of 35 nM). The diazo-containing inhibitors 8a, 8c, and 10a were irradiated at 340 nm to give a photostationary state enriched in the (Z)-isomer, and in all cases, these were less active. The most water soluble triazene 17a (IC50 of 90 nM) retards calpain-induced cataract formation in lens culture.
Subject(s)
Aldehydes/chemical synthesis , Azo Compounds/chemical synthesis , Calpain/antagonists & inhibitors , Cataract/drug therapy , Dipeptides/chemical synthesis , Sulfonamides/chemical synthesis , Triazenes/chemical synthesis , Ultraviolet Rays , Aldehydes/chemistry , Aldehydes/pharmacology , Animals , Azo Compounds/chemistry , Azo Compounds/pharmacology , Calpain/metabolism , Cataract/enzymology , Culture Techniques , Dipeptides/chemistry , Dipeptides/pharmacology , Humans , Lens, Crystalline/drug effects , Models, Molecular , Protein Binding , Protein Structure, Tertiary , Sheep , Stereoisomerism , Structure-Activity Relationship , Sulfonamides/chemistry , Sulfonamides/pharmacology , Triazenes/chemistry , Triazenes/pharmacologyABSTRACT
A new cyclic pentapeptide, chrysosporide (1), was isolated from a New Zealand sample of the mycoparasitic fungus Sepedonium chrysospermum by bioactivity-guided fractionation. The planar structure was deduced by detailed spectroscopic analysis, and the absolute configurations of the amino acid residues were defined by Marfey's method. As both enantiomers of Leu occurred in chrysosporide, molecular mechanics calculations were applied to the analysis to distinguish between the possible structural isomers. Only the lowest energy conformers of the cyclo-(L-Val-D-Ala-L-Leu-L-Leu-D-Leu) isomer were in agreement with the observed NOEs, suggesting that this was the most probable amino acid sequence for chrysosporide (1).
Subject(s)
Ascomycota/chemistry , Peptides, Cyclic/chemistry , Peptides, Cyclic/isolation & purification , Amino Acid Sequence , Animals , Crystallography, X-Ray , Drug Screening Assays, Antitumor , Leukemia P388 , Mice , Models, Chemical , Molecular Structure , New Zealand , Peptides, Cyclic/pharmacology , Protein Conformation , StereoisomerismABSTRACT
In the course of the development of calpain inhibitors, we report the synthesis of eight-membered cyclic pseudo dipeptides closely related to the known inhibitor SJA6017. The ring closure was effected by metathesis of the diallyl-substituted dipeptides 6 and 7. The formation of the dipeptides under kinetic control leads to the preferential formation of the unlike diastereomer 7 over the like diastereomer 6. The relative configuration of the diastereomers was determined by NMR and modeling studies of the related cyclic compounds 8 and 9 and their derivatives. The compounds proved not to inhibit calpain.
