Design and synthesis of pyrrolidine-5,5-trans-lactams (5-oxohexahydropyrrolo[3,2-b]pyrroles) as novel mechanism-based inhibitors of human cytomegalovirus protease. 2. Potency and chirality.
The stereospecific synthesis of a series of alpha-methylpyrrolidine-5,5-trans-lactam inhibitors of human cytomegalovirus (HCMV) protease is described. Examination of the SAR in this series has defined the size and chirality of the alpha-substituent, optimized the acyl substituent on the lactam nitrogen, and defined the steric constraint of this functionality. The SAR of the functionality on the pyrrolidine nitrogen of the trans-lactam has been investigated, and this has led to the discovery of potent serine protease inhibitors that are highly selective for the viral enzyme over the mammalian enzymes elastase, thrombin, and acetylcholine esterase. The mechanism of action of our lead compounds has been established by mass spectrometry, and enzymatic degradation of HCMV deltaAla protease acylated with these inhibitors showed that Ser 132 is the active site nucleophile. The crystal structure of HCMV protease was obtained and used to model the conformationally restricted, chiral (S)-proline-alpha-methyl-5,5-trans-lactams into the active site groove of the enzyme, enabling us to direct and rationalize the SAR in this series. The activity against HCMV deltaAla protease is the greatest with inhibitors based on the dansyl-(S)-proline alpha-methyl-5,5-trans-lactam template, which have low nanomolar activity against the viral enzyme.
Borthwick
Alan D
AD
Department of Medicinal Chemistry CVU UK, GlaxoSmithKline Research and Development, Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts SG1 2NY, UK. adb3028@glaxowellcome.co.uk
Crame
Andrew J
AJ
Ertl
Peter F
PF
Exall
Anne M
AM
Haley
Terry M
TM
Hart
Graham J
GJ
Mason
Andrew M
AM
Pennell
Andrew M K
AM
Singh
Onkar M P
OM
Weingarten
Gordon G
GG
Woolven
James M
JM
D000998:Antiviral Agents / Q000138:chemical synthesis* / Q000737:chemistry; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003587:Cytomegalovirus / Q000737:chemistry*; D007769:Lactams / Q000138:chemical synthesis* / Q000737:chemistry; D013058:Mass Spectrometry; D008958:Models, Molecular; D011480:Protease Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D000998:Antiviral Agents; D007769:Lactams; D011480:Protease Inhibitors; D011758:Pyrroles; D012697:Serine Endopeptidases; C071910:assemblin