New sialyl Lewis(x) mimic containing an alpha-substituted beta(3)-amino acid spacer

A highly convergent and efficient synthesis of a new sialyl Lewis(x) (sLe(x)) mimic, which was predicted by computational studies to fulfil the spacial requirements for a selectin antagonist, has been developed. With a beta(2,3)-amino acid residue l-galactose (bioisostere of the l-fucose moiety present in the natural sLe(x)) and succinate are linked, leading to a mimic of sLe(x) that contains all the required pharmacophores, namely the 3- and 4-hydroxy group of l-fucose, the 4- and 6-hydroxy group of d-galactose and the carboxylic acid of N-acetylneuraminic acid. The key step of the synthesis involves a tandem reaction consisting of a N-deprotection and a suitable O-->N intramolecular acyl migration reaction which is promoted by cerium ammonium nitrate (CAN). Finally, the new sialyl Lewis(x) mimic was biologically evaluated in a competitive binding assay.     

Production of a complement inhibitor possessing sialyl Lewis X moieties by in vitro glycosylation technology

Recombinant soluble human complement receptor type 1 (sCR1) is a highly glycosylated glycoprotein intended for use as a drug to treat ischemia-reperfusion injury and other complement-mediated diseases and injuries. sCR1-sLe(x) produced in the FT-VI-expressing mutant CHO cell line LEC11 exists as a heterogeneous mixture of glycoforms, a fraction of which include structures with one or more antennae terminated by the sialyl Lewis X (sLe(x)) [Neu5Acalpha2-3Galbeta1-4(Fucalpha1-3)GlcNAc]) epitope. Such multivalent presentation of sLe(x) was shown previously to effectively target sCR1 to activated endothelial cells expressing E-selectin. Here, we describe the use of the soluble, recombinant alpha2-3 sialyltransferase ST3Gal-III and the alpha1-3 fucosyltransferase FT-VI in vitro to introduce sLe(x) moieties onto the N-glycan chains of sCR1 overexpressed in standard CHO cell lines. The product (sCR1-S/F) of these in vitro enzymatic glycan remodeling reactions performed at the 10-g scale has approximately 14 N-glycan chains per sCR1 molecule, comprised of biantennary (90%), triantennary (8.5%), and tetraantennary (1.5%) structures, nearly all of whose antennae terminate with sLe(x) moieties. sCR1-S/F retained complement inhibitory activity and, in comparison with sCR1-sLe(x) produced in the LEC11 cell line, contained twice the number of sLe(x) moieties per mole glycoprotein, exhibited a twofold increase in area under the intravenous clearance curve in a rat pharmacokinetic model, and exhibited a 10-fold increase in affinity for E-selectin in an in vitro binding assay. These results demonstrate that in vitro glycosylation of the sCR1 drug product reduces heterogeneity of the glycan profile, improves pharmacokinetics, and enhances carbohydrate-mediated binding to E-selectin.     

Selectin/glycoconjugate binding assays for the identification and optimization of selectin antagonists.

In this study we describe ELISA-type P- and L-selectin binding assays for the analysis of selectin antagonists. A biotinylated polyacrylamide-type glycoconjugate containing sialyl Lewis A (sLe(a)-polymer) is utilized as a synthetic ligand for both selectins analogous to the E-selectin assay we have developed recently. Following precomplexation of sLe(a)-polymer with streptavidin-peroxidase, the complex is added to microtiter plates coated with the recombinant selectins. Binding of sLe(a)-polymer to the immobilized selectins is measured by the peroxidase reaction. SLe(a)-polymer was found to bind to P- and L-selectin in a cation-dependent manner. The interaction of the polymer was blocked by neutralizing anti-P- and anti-L-selectin antibody, respectively. The reference compounds heparin and fucoidan inhibited in both assays. Sialyl Lewis X (sLe(x)) blocked binding to L-selectin by 46% at 3 mM, whereas no inhibition was observed in the P-selectin assay up to 3 mM. Control polymers containing sialic acid or beta-d-glucose instead of sLe(a) weakly bound or failed to bind to the selectins. Both assays are rapid to perform and of low variability. The P-selectin assay was successfully employed to identify and optimize novel carbohydrate-based P-selectin antagonists. The P-, L-, and E-selectin assays were used to determine the fine selectivity of several sLe(x)-related selectin antagonists. These studies together suggest that sLe(a)-polymer-based selectin assays are well suited for primary screening and the characterization of selectin antagonists.     

Polymerized liposome assemblies: bifunctional macromolecular selectin inhibitors mimicking physiological selectin ligands

Monomeric sialyl Lewis(X) (sLe(x)) and sLe(x)-like oligosaccharides are minimal structures capable of supporting selectin binding in vitro. However, their weak binding interactions do not correlate with the high-affinity binding interactions witnessed in vivo. The polyvalent display of carbohydrate groups found on cell surface glycoprotein structures may contribute to the enhanced binding strength of selectin-mediated adhesion. Detailed biochemical analyses of physiological selectin ligands have revealed a complicated composition of molecules that bind to the selectins in vivo and suggest that there are other requirements for tight binding beyond simple carbohydrate multimerization. In an effort to mimic the high-affinity binding, polyvalent scaffolds that contain multicomponent displays of selectin-binding ligands have been synthesized. Here, we demonstrate that the presentation of additional anionic functional groups in the form of sulfate esters, on a polymerized liposome surface containing a multimeric array of sLe(x)-like oligosaccharides, generates a highly potent, bifunctional macromolecular assembly. This assembly inhibits L-, E-, and P-selectin binding to GlyCAM-1, a physiological ligand better than sLe(x)-like liposomes without additional anionic charge. These multivalent arrays are 4 orders of magnitude better than the monovalent carbohydrate. Liposomes displaying 3'-sulfo Lewis(X)-like oligosaccharides, on the other hand, show slight loss of binding with introduction of additional anionic functional groups for E- and P-selectin and negligible change for L-selectin. The ability to rapidly and systematically vary the composition of these assemblies is a distinguishing feature of this methodology and may be applied to the study of other systems where composite binding determinants are important for high-affinity binding.     

Discovery of substituted 4-anilino-2-(2-pyridyl)pyrimidines as a new series of apoptosis inducers using a cell- and caspase-based high throughput screening assay. Part 1: structure-activity relationships of the 4-anilino group

A series of 4-anilino-2-(2-pyridyl)pyrimidines has been discovered as a new class of potent inducers of apoptosis using a cell-based HTS assay. Compound 5a was found to arrest T47D cells in G2/M and induced apoptosis. SAR studies showed that a small and electron-donating group at the meta-position of the anilino ring is important for activity. A 20-fold increase in potency, from hit compound 4-(3-methoxyanilino)-2-(2-pyridinyl)-6-(trifluoromethyl)pyrimidine (5a) to lead compound 4-(2,5-dimethoxyanilino)-2-(2-pyridinyl)-6-(trifluoromethyl)pyrimidine (5l), was obtained through the SAR studies. Compound 5l is highly active with an EC50 value of 18 nM in the caspase activation assay in T47D breast cells. Interestingly, 5a and other meta-mono-substituted compounds were active against T47D cells but were not active against H1299 and HT29 cells, while 5l and other 2,5-disubstituted compounds were active against all the three cells. In a tubulin polymerization assay, compound 5l inhibited tubulin polymerization with an IC50 value of < 0.5 microM, while 5a was not active up to 50 microM.     

The alpha (1,3)-fucosyltransferase Fuc-TIV,but not Fuc-TVII,generates sialyl Lewis X-like epitopes preferentially on glycolipids

Fuc-TIV and Fuc-TVII are the two alpha(1, 3)-fucosyltransferases in myeloid cells responsible for the biosynthesis of sialyl Lewis X (sLe(x)), the minimal ligand structure for the selectins. We have compared the ability of Fuc-TIV and Fuc-TVII to generate sLe(x)-like epitopes in transfected Chinese hamster ovary (CHO)-Pro(-)5 cells expressing the P-selectin glycoprotein ligand-1 and the core-2 branching enzyme C2GnT. We found that mouse Fuc-TIV and Fuc-TVII can generate similar levels of cell surface sLe(x). Surprisingly however, Fuc-TIV-generated sLe(x) was resistant to proteinase K and trypsin treatment and could be removed from cells by delipidation with chloroform/methanol, whereas 80-90% of Fuc-TVII-generated sLe(x) was protease-sensitive, and most of it resistant to delipidation. Despite similar levels of sLe(x) on the cell surface, Fuc-TVII transfectants adhered to immobilized E-selectin-IgG under static and flow conditions better than Fuc-TIV transfectants. Binding was mainly protease sensitive, indicating that glycoproteins were more efficient ligands than glycolipids. In summary, we conclude that the two fucosyltransferases differ in their in vivo specificity for acceptor substrates with Fuc-TVII generating sLe(x) preferentially on glycoproteins, whereas most of the Fuc-TIV-generated sLe(x) is found on glycolipids. Interestingly, the non-catalytic portion of Fuc-TIV in a Fuc-TIV/VII chimeric enzyme mediated the specificity for glycolipid substrates.     

sLea and sLex expression in colorectal cancer: implications for tumourigenesis and disease prognosis

The glycoconjugates expressed by cancer cells frequently contain sialylated oligosaccharide chains. Among these oligosaccharides the sialyl Lewis a (sLe(a)) and sialyl Lewis x (sLe(x)) antigens are found to be overexpressed in tumours of different origin. The current study assesses sLe(a) and sLe(x) expression in different colorectal specimens in order to establish the correlation of these biomarkers with both malignant transformation of colorectal mucosa and the progression of colorectal cancer (CRC). Healthy disease-free and inflammatory mucosa specimens showed no presence of the antigens. sLe(a) was expressed in 6.7% of the healthy tissue from CRC patients, in 20.8% of the adenomas, and in 33.3% and 42.6% of the transitional tissue and tumour tissue, respectively. sLe(x) expression was observed in 6.7% of the healthy tissue from CRC patients, in 27.0% of the adenomas, and in 25.6% and 74.8% of the transitional and the tumour tissue, respectively. The expression of the sLe(a) and sLe(x) antigens was correlated in adenomas, as well as in healthy and tumour tissue from CRC. Moreover, the high expression of sLe(x) in adenomas was correlated with a high degree of dysplasia (p=0.042). Finally, the survival analysis suggested that sLe(a) expression may be a prognostic factor for predicting disease-free survival in colorectal cancer (p=0.012).     

Novel 3,5-diaryl pyrazolines and pyrazole as low-density lipoprotein (LDL) oxidation inhibitor

Compounds 4a-j and 5 were synthesized by cyclocondensation of 3a-j and hydrazine and showed significant LDL-antioxidant activities in the TBARS assay, the lag time of conjugated diene production, the relative electrophoretic mobility (REM) of ox-LDL, the apoB-100 fragmentation, and the macrophage-mediated LDL oxidation. Among compounds 4a-j and 5, 4a was found to be the most active compound as an inhibitor of LDL oxidation and 4a (IC50 = 0.1 microM) was 6-fold more potent than probucol (IC50 = 0.6 microM) in the TBARS assay.     

Resolution, configurational assignment, and enantiopharmacology of 2-amino-3-[3-hydroxy-5-(2-methyl-2H- tetrazol-5-yl)isoxazol-4-yl]propionic acid, a potent GluR3- and GluR4-preferring AMPA receptor agonist

We have previously shown that (RS)-2-amino-3-[3-hydroxy-5-(2-methyl-2H-tetrazol-5-yl)isoxazol -4-yl] propionic acid (2-Me-Tet-AMPA) is a selective agonist at (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors, markedly more potent than AMPA itself, whereas the isomeric compound 1-Me-Tet-AMPA is essentially inactive. We here report the enantiopharmacology of 2-Me-Tet-AMPA in radioligand binding and cortical wedge electrophysiological assay systems, and using cloned AMPA (GluR1-4) and kainic acid (KA) (GluR5, 6, and KA2) receptor subtypes expressed in Xenopus oocytes. 2-Me-Tet-AMPA was resolved using preparative chiral HPLC. Zwitterion (-)-2-Me-Tet-AMPA was assigned the (R)-configuration based on an X-ray crystallographic analysis supported by the elution order of (-)- and (+)-2-Me-Tet-AMPA using four different chiral HPLC columns and by circular dichroism spectra. None of the compounds tested showed detectable affinity for N-methyl-D-aspartic acid (NMDA) receptor sites, and (R)-2-Me-Tet-AMPA was essentially inactive in all of the test systems used. Whereas (S)-2-Me-Tet-AMPA showed low affinity (IC(50) = 11 microM) in the [(3)H]KA binding assay, it was significantly more potent (IC(50) = 0.009 microM) than AMPA (IC(50) = 0.039 microM) in the [(3)H]AMPA binding assay, and in agreement with these findings, (S)-2-Me-Tet-AMPA (EC(50) = 0.11 microM) was markedly more potent than AMPA (EC(50) = 3.5 microM) in the electrophysiological cortical wedge model. In contrast to AMPA, which showed comparable potencies (EC(50) = 1.3-3.5 microM) at receptors formed by the AMPA receptor subunits (GluR1-4) in Xenopus oocytes, more potent effects and a substantially higher degree of subunit selectivity were observed for (S)-2-Me-Tet-AMPA: GluR1o (EC(50) = 0.16 microM), GluR1o/GluR2i (EC(50) = 0.12 microM), GluR3o (EC(50) = 0.014 microM) and GluR4o (EC(50) = 0.009 microM). At the KA-preferring receptors GluR5 and GluR6/KA2, (S)-2-Me-Tet-AMPA showed much weaker agonist effects (EC(50) = 8.7 and 15.3 microM, respectively). It is concluded that (S)-2-Me-Tet-AMPA is a subunit-selective and highly potent AMPA receptor agonist and a potentially useful tool for studies of physiological AMPA receptor subtypes.     

Glycomic mapping of pseudomucinous human ovarian cyst glycoproteins: identification of Lewis and sialyl Lewis glycotopes

Expression of sialyl Lewis x (sLe(x)) and sialyl Lewis a (sLe(a)) on cell-surface glycoproteins endows cells with the ability to adhere to E-, P-, and L-selectins present on endothelia, platelets, or leukocytes. Special arrangements of these glycotopes in cancers are thought to play a key role in metastasis. Previous studies have mostly described membrane-bound sLe(x) and sLe(a) activities. In this report, the major O-glycans of the secreted human ovarian cyst sialoglycoproteins from a Le(a+) nonsecretor individual (human ovarian cyst sample 350) were characterized by MS/MS analyses and immuno-/lectin-chemical assays. The results showed that HOC 350 carries a large number of epitopes for sLe(x), sLe(a), and Le(a) reactive antibodies. Advanced MS/MS sequencing coupled with mild periodate oxidation and exoglycosidase digestions further revealed that the O-glycans from HOC 350 are mostly of core 1 and 2 structures, extended and branched on the 3-arm with both type I and type II chains, complete with variable degrees of terminal sialylation and/or fucosylation to yield the sLe(x) or sLe(a) epitopes. Thus, the underlying core and peripheral backbone structures are similar to that of a previously proposed composite structural model for nonsialylated human ovarian cysts O-glycans, but with some notable distinguishing structural features in addition to sialylation.     

Low-density lipoprotein (LDL)-antioxidant lignans from Myristica fragrans seeds

Six diarylbutane lignans 1-5 and one aryltetralin lignan 6 were isolated from the methanol (95%) extracts of Myristica fragrans seeds and then 7-methyl ether diarylbutane lignan 4 has proven to be new a compound. Their compounds 1-7 were evaluated for LDL-antioxidant activity to identify the most potent LDL-antioxidant 3 with an IC50 value of 2.6 microM in TBARS assay. Due to its potency, compound 3 was tested for complementary in vitro investigations, such as lag time (140 min at 1.0 microM), relative electrophoretic mobility (REM) of ox-LDL (inhibition of 80% at 20 microM and 72% at 10 microM), and fragmentation of apoB-100 (inhibition of 93% at 20 microM) on copper-mediated LDL oxidation. In macrophage-mediated LDL oxidation, the TBARS formation was also inhibited by compound 3.     

A novel glycosulfopeptide binds to P-selectin and inhibits leukocyte adhesion to P-selectin.

P-selectin glycoprotein ligand-1 (PSGL-1) is a dimeric membrane mucin on leukocytes that binds selectins. The molecular features of PSGL-1 that determine this high affinity binding are unclear. Here we demonstrate the in vitro synthesis of a novel glycosulfopeptide (GSP-6) modeled after the extreme N terminus of PSGL-1, which has been predicted to be important for P-selectin binding. GSP-6 contains three tyrosine sulfate (TyrSO(3)) residues and a monosialylated, core 2-based O-glycan with a sialyl Lewis x (C2-O-sLe(x)) motif at a specific Thr residue. GSP-6 binds tightly to immobilized P-selectin, whereas glycopeptides lacking either TyrSO(3) or C2-O-sLe(x) do not detectably bind. Remarkably, an isomeric glycosulfopeptide to GSP-6, termed GSP-6', which contains sLe(x) on an extended core 1-based O-glycan, does not bind immobilized P-selectin. Equilibrium gel filtration analysis revealed that GSP-6 binds to soluble P-selectin with a K(d) of approximately 350 nM. GSP-6 (<5 microM) substantially inhibits neutrophil adhesion to P-selectin in vitro, whereas free sLe(x) (5 mM) only slightly inhibits adhesion. In contrast to the inherent heterogeneity of post-translational modifications of recombinant proteins, glycosulfopeptides permit the placement of sulfate groups and glycans of precise structure at defined positions on a polypeptide. This approach should expedite the probing of structure-function relationships in sulfated and glycosylated proteins, and may facilitate development of novel drugs to treat inflammatory diseases involving P-selectin-mediated leukocyte adhesion.     

Synthesis and in vitro anti-HIV activities of didanosine prodrugs

A series of prodrugs of didanosine were synthesized in an effort to enhance the anti-HIV activity. The 5'-OH function of didanosine was esterified with different aryl piperazine acetic acid derivatives and evaluated for anti-HIV-1 activity in MT-4 cell line using the MTT assay method. Among the synthesized compounds, (tetrahydro-5-(1,6-dihydro-6-oxopurin-9-yl)furan-2-yl)methyl 2-(4-(4-chlorophenyl)piperazin-1-yl)acetate (4b) was found to be the most potent compound with EC50 of 0.64 microM and was not toxic to the MT-4 cells up to 1000 microM with a selectivity index of > 1562. Compound 4b was found to be seven times more potent than the parent drug didanosine (EC50 of 4.8 microM) in vitro. In vitro hydrolysis of the various esters in human plasma indicated that these agents were relatively stable toward plasma esterases with t1/2 ranging from 20-60 min.     

Discovery of 5-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7-phenyl-(E)-2,3,6,7-tetrahydro-1,4-thiazepines as a new series of apoptosis inducers using a cell- and caspase-based HTS assay

We report the discovery of 5-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7-(4-methylphenyl)-(E)-2,3,6,7-tetrahydro-1,4-thiazepine (2a) as an inducer of apoptosis using our proprietary cell- and caspase-based HTS assay. Through structure activity relationship (SAR) studies, 5-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7-(2-methoxy-4-(methylthio)phenyl)-(E)-2,3,6,7-tetrahydro-1,4-thiazepine (5d) was identified as a potent apoptosis inducer with an EC(50) value of 0.08 microM in T47D cells, which was >15-fold more potent than screening hit 2a. Compound 5d also was found to be highly active in a growth inhibition assay with a GI(50) value of 0.05 microM in T47D cells and to function as an inhibitor of tubulin polymerization.     

Affinity and kinetics of sialyl Lewis-X and core-2 based oligosaccharides binding to L- and P-selectin

Soluble oligosaccharide mimetics of natural selectin ligands act as competitive inhibitors of leukocyte adhesion in models of inflammation. We quantified the binding of simple oligosaccharides based on sialyl Lewis-X (sLe(X)) and complex molecules with the core-2 structure to L- and P-selectin, under both static and fluid flow conditions. Isolated human neutrophils were employed to mimic the physiological valency of selectins and selectin ligands. Surface plasmon resonance studies quantified binding kinetics. We observed the following: (i) The functional group at the anomeric position of carbohydrates plays an important role during selectin recognition, since sLe(X) and sialyl Lewis-a (sLe(a)) were approximately 5-7-fold poorer inhibitors of L-selectin mediated cell adhesion compared to their methyl glycosides. (ii) Despite their homology to physiological glycans, the putative carbohydrate epitopes of GlyCAM-1 and PSGL-1 bound selectins with low affinity comparable to that of sLe(X)-selectin interactions. Thus, besides the carbohydrate portion, the protein core of GlyCAM-1 or the presentation of carbohydrates in clusters on this glycoprotein may contribute to selectin recognition. (iii) A compound Galbeta1,4(Fucalpha1,3)GlcNAcbeta1,6(GalNAcbeta1,3)GalNAcalpha-OMe was identified which blocked L- and P-selectin binding at 30-100-fold lower doses than sLe(X). (iv) Surface plasmon resonance experiments determined that an sLe(X) analogue (TBC1269) competitively inhibited, via steric/allosteric mechanisms, the binding of two anti-P-selectin function blocking antibodies that recognized different epitopes of P-selectin. (v) TBC1269 bound P-selectin via both calcium-dependent and -independent mechanisms, with K(D) of approximately 111.4 microM. The measured on- and off-rates were high (k(off) > 3 s(-)(1), k(on) > 27,000 M(-)(1) s(-)(1)). Similar binding kinetics are expected for sLe(X)-selectin interactions. Taken together, our study provides new insight into the kinetics and mechanisms of carbohydrate interaction with selectins.     

Pre-clinical evaluation of an sLe x-glycosylated complement inhibitory protein in a non-human primate model of reperfused stroke

BACKGROUND: Soluble complement receptor-1 (sCR1), a potent complement inhibitor, confers neuroprotection in a murine stroke model. Additional neuroprotective benefit is achieved by sLe x-glycosylation of sCR1. In an effort to translate sCR1-sLe x to clinical trials, we evaluated this agent in a primate stroke model. METHODS: Adult male baboons randomly received either sCR1-sLe x or vehicle. Stroke volume was assessed on day 3, and neurological examinations were conducted daily. Complement activity (CH50) was measured at 30 minute, 2, 6, 12 hour, 3, and 10 days post-ischemia. RESULTS: The experiment was terminated prematurely following an interim analysis. In a preliminary cohort (n = 3 per arm), infarct volume was greater in the treated animals. No difference in neurological score was found between groups. CH50 levels were significantly reduced in the sCR1sLe x-treated groups. A hypotensive response was also observed in animals treated with sCR1-sLe x. Conclusions Further work is necessary to explain the hypotensive response observed in primates prior to further clinical development of sCR1-sLe x.     

Sialyl Lewis(x)-mediated, PSGL-1-independent rolling adhesion on P-selectin

Selectin-mediated cell adhesion is an essential component of the inflammatory response. In an attempt to unambiguously identify molecular features of ligands that are necessary to support rolling adhesion on P-selectin, we have used a reconstituted ("cell-free") system in which ligand-coated beads are perfused over soluble P-selectin surfaces. We find that beads coated with the saccharides sialyl Lewis(x) (sLe(x)), sialyl Lewis(a) (sLe(a)), and sulfated Lewis(x) (HSO(3)Le(x) support rolling adhesion on P-selectin surfaces. Although it has been suggested that glycosylation and sulfation of P-selectin glycoprotein ligand-1 (PSGL-1) is required for high-affinity binding and rolling on P-selectin, our findings indicate that sulfation of N-terminal tyrosine residues is not required for binding or rolling. However, beads coated with a tyrosine-sulfated, sLe(x)-modified, PSGL-1-Fc chimera support slower rolling on P-selectin than beads coated with sLe(x) alone, suggesting that sulfation improves rolling adhesion by modulating binding to P-selectin. In addition, we find it is not necessary that P-selectin carbohydrate ligands be multivalent for robust rolling to occur. Our results demonstrate that beads coated with monovalent sLe(x), exhibiting a more sparse distribution of carbohydrate than a similar amount of the multivalent form, are sufficient to yield rolling adhesion. The relative abilities of various ligands to support rolling on P-selectin are quantitatively examined among themselves and in comparison to human neutrophils. Using stop-time distributions, rolling dynamics at video frame rate resolution, and the average and variance of the rolling velocity, we find that P-selectin ligands display the following quantitative trend, in order of decreasing ability to support rolling adhesion on P-selectin: PSGL-1-Fc > sLe(a) approximately sLe(x) > HSO(3)Le(x).     

Discovery of highly potent small molecule Hepatitis C Virus entry inhibitors

Novel, highly potent small molecule HCV entry inhibitors are reported. The SAR exploration of a hit molecule identified from screening of a compound library led to the identification of highly potent compounds with IC(50) values of <5 nM in the tissue culture HCV infectious assay.