Dihydroxylphenyl amides as inhibitors of the Hsp90 molecular chaperone.

Information from X-ray crystal structures were used to optimize the potency of a HTS hit in a Hsp90 competitive binding assay. A class of novel and potent small molecule Hsp90 inhibitors were thereby identified. Enantio-pure compounds 31 and 33 were potent in PGA-based competitive binding assay and inhibited proliferation of various human cancer cell lines in vitro, with IC(50) values averaging 20 nM.

Tricyclic benzimidazoles as potent poly(ADP-ribose) polymerase-1 inhibitors.

Novel tricyclic benzimidazole carboxamide poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors have been synthesized. Several compounds were found to be powerful chemopotentiators of temozolomide and topotecan in both A549 and LoVo cell lines. In vitro inhibition of PARP-1 was confirmed by direct measurement of NAD+ depletion and ADP-ribose polymer formation caused by chemically induced DNA damage.

Novel tricyclic poly(ADP-ribose) polymerase-1 inhibitors with potent anticancer chemopotentiating activity: design, synthesis, and X-ray cocrystal structure.

A series of novel compounds have been designed that are potent inhibitors of poly(ADP-ribose) polymerase-1 (PARP-1), and the activity and physical properties have been characterized. The new structural classes, 3,4,5,6-tetrahydro-1H-azepino[5,4,3-cd]indol-6-ones and 3,4-dihydropyrrolo[4,3,2-de]isoquinolin-5-(1H)-ones, have conformationally locked benzamide cores that specifically interact with the PARP-1 protein. The compounds have been evaluated with in vitro cellular assays that measure the ability of the PARP-1 inhibitors to enhance the effect of cytotoxic agents against cancer cell lines.

Design, synthesis, and biological evaluation of novel human 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAP) substrates.

The structure-based design, chemical synthesis, and biological evaluation of novel MTAP substrates are described. These compounds incorporate various C5'-moieties and are shown to have different k(cat)/K(m) values compared with the natural MTAP substrate (MTA).

Crystallographic identification of a noncompetitive inhibitor binding site on the hepatitis C virus NS5B RNA polymerase enzyme.

The virus-encoded nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) is an RNA-dependent RNA polymerase and is absolutely required for replication of the virus. NS5B exhibits significant differences from cellular polymerases and therefore has become an attractive target for anti-HCV therapy. Using a high-throughput screen, we discovered a novel NS5B inhibitor that binds to the enzyme noncompetitively with respect to nucleotide substrates. Here we report the crystal structure of NS5B complexed with this small molecule inhibitor. Unexpectedly, the inhibitor is bound within a narrow cleft on the protein's surface in the "thumb" domain, about 30 A from the enzyme's catalytic center. The interaction between this inhibitor and NS5B occurs without dramatic changes to the structure of the protein, and sequence analysis suggests that the binding site is conserved across known HCV genotypes. Possible mechanisms of inhibition include perturbation of protein dynamics, interference with RNA binding, and disruption of enzyme oligomerization.