Synthesis and evaluation of peptidyl Michael acceptors that inactivate human rhinovirus 3C protease and inhibit virus replication.
Human rhinovirus, the chief cause of the common cold, contains a positive-sense strand of RNA which is translated into a large polyprotein in infected cells. Cleavage of the latter to produce the mature viral proteins required for replication is catalyzed in large part by a virally encoded cysteine proteinase (3Cpro) which is highly selective for -Q approximately GP- cleavage sites. We synthesized peptidyl derivatives of vinylogous glutamine or methionine sulfone esters (e.g., Boc-Val-Leu-Phe-vGln-OR: R = Me, 1; R = Et, 2) and evaluated them as inhibitors of HRV-14 3C protease (3Cpro). Compounds 1 and 2 and several related tetra- and pentapeptide analogues rapidly inactivated 3Cpro with submicromolar IC50 values. Electrospray mass spectrometry confirmed the expected 1:1 stoichiometry of 3Cpro inactivation by 1, 2, and several other analogues. Compound 2 also proved to be useful for active site titration of 3Cpro, which has not been possible heretofore because of the lack of a suitable reagent. In contrast to 1, 2, and congeners, peptidyl Michael acceptors lacking a P4 residue have greatly reduced or negligible activity against 3Cpro, consistent with previously established structure-activity relationships for 3Cpro substrates. Hydrolysis of the P1 vinylogous glutamine ester to a carboxylic acid also decreased inhibitory activity considerably, consistent with the decreased reactivity of acrylic acids vs acrylic esters as Michael acceptors. Incorporating a vinylogous methionine sulfone ester in place of the corresponding glutamine derivative in 1 also reduced activity substantially. Compounds 1 and 2 and several of their analogues inhibited HRV replication in cell culture by 50% at low micromolar concentrations while showing little or no evidence of cytotoxicity at 10-fold higher concentrations. Peptidyl Michael acceptors and their analogues may prove useful as therapeutic agents for pathologies involving cysteine proteinase enzymes.
Kong
J S
JS
Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045-2506, USA.
Venkatraman
S
S
Furness
K
K
Nimkar
S
S
Shepherd
T A
TA
Wang
Q M
QM
Aubé
J
J
Hanzlik
R P
RP
D000086042:3C Viral Proteases; D000998:Antiviral Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000187:drug effects; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D015195:Drug Design; D005973:Glutamine / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D012229:Rhinovirus / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D013329:Structure-Activity Relationship; D014764:Viral Proteins; D014779:Virus Replication / Q000187:drug effects*
D000998:Antiviral Agents; D015853:Cysteine Proteinase Inhibitors; D010455:Peptides; D014764:Viral Proteins; D005973:Glutamine; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases