Design, synthesis, and evaluation of nonpeptidic inhibitors of human rhinovirus 3C protease.
The design, synthesis, and biological evaluation of reversible, nonpeptidic inhibitors of human rhinovirus (HRV) 3C protease (3CP) are reported. A novel series of 2,3-dioxindoles (isatins) were designed that utilized a combination of protein structure-based drug design, molecular modeling, and structure-activity relationship (SAR). The C-2 carbonyl of isatin was envisioned to react in the active site of HRV 3CP with the cysteine responsible for catalytic proteolysis, thus forming a stabilized transition state mimic. Molecular-modeling experiments using the apo crystal structure of human rhinovirus-serotype 14 (HRV-14) 3CP and a peptide substrate model allowed us to design recognition features into the P1 and P2 subsites, respectively, from the 5- and 1-positions of isatin. Attempts to optimize recognition properties in the P1 subsite using SAR at the 5-position were performed. In addition, a series of ab initio calculations were carried out on several 5-substituted isatins to investigate the stability of sulfide adducts at C-3. The inhibitors were prepared by general synthetic methods, starting with commercially available 5-substituted isatins in nearly every case. All compounds were tested for inhibition of purified HRV-14 3CP. Compounds 8, 14, and 19 were found to have excellent selectivity for HRV-14 3CP compared to other proteolytic enzymes, including chymotrypsin and cathepsin B. Selected compounds were assayed for antiviral activity against HRV-14-infected HI-HeLa cells. A 2.8 A cocrystal structure of derivative 19 covalently bound to human rhinovirus-serotype 2 (HRV-2) 3CP was solved and revealed that the isatin was situated in essentially the same conformation as modeled.
Webber
S E
SE
Agouron Pharmaceuticals, Inc., San Diego, California 92121, USA.
Tikhe
J
J
Worland
S T
ST
Fuhrman
S A
SA
Hendrickson
T F
TF
Matthews
D A
DA
Love
R A
RA
Patick
A K
AK
Meador
J W
JW
Ferre
R A
RA
Brown
E L
EL
DeLisle
D M
DM
Ford
C E
CE
Binford
S L
SL
D000086042:3C Viral Proteases; D000998:Antiviral Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D011480:Protease Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D013816:Thermodynamics; D014764:Viral Proteins
D000998:Antiviral Agents; D011480:Protease Inhibitors; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases