Increasing selectivity of CC chemokine receptor 8 antagonists by engineering nondesolvation related interactions with the intended and off-target binding sites.

The metabolic stability and selectivity of a series of CCR8 antagonists against binding to the hERG ion channel and cytochrome Cyp2D6 are studied by principal component analysis. It is demonstrated that an efficient way of increasing metabolic stability and selectivity of this series is to decrease compound lipophilicity by engineering nondesolvation related attractive interactions with CCR8, as rationalized by three-dimensional receptor models. Although such polar interactions led to increased compound selectivity, such a strategy could also jeopardize the DMPK profile of compounds. However, once increased potency is found, the lipophilicity can be readjusted by engineering hydrophobic substituents that fit to CCR8 but do not fit to hERG. Several such lipophilic fragments are identified by two-dimensional fragment-based QSAR analysis. Electrophysiological measurements and site-directed mutagenesis studies indicated that the repulsive interactions of these fragments with hERG are caused by steric hindrances with residue F656.

Identification and optimisation of a series of substituted 5-pyridin-2-yl-thiophene-2-hydroxamic acids as potent histone deacetylase (HDAC) inhibitors.

Further investigation of a series of thienyl-based hydroxamic acids that included ADS100380 and ADS102550 led to the identification of the 5-pyridin-2-yl-thiophene-2-hydroxamic acid 3c, which possessed modest HDAC inhibitory activity. Substitution at the 5- and 6-positions of the pyridyl ring of compound 3c provided compounds 5a-g, 7a, b, 9, and 13a. Compound 5b demonstrated improved potency, in vitro DMPK profile, and rat oral bioavailability, compared to ADS102550. Functionalisation of the pendent phenyl group of compounds 5b, 5e and 13a provided analogues that possessed excellent enzyme inhibition and anti-proliferative activity.

Synthesis of a non-heme template for attaching four peptides: an approach to artificial iron(II)-containing peroxidases.

We are developing all-synthetic model cofactor-protein complexes in order to define the parameters controlling non-natural cofactor activity. The long-term objective is to establish the theoretical and practical basis for designing novel enzymes. A non-heme pentadentate ligand (N4Py) is being developed as a template for the site-specific attachment of a designed four-helix bundle. Previously, we attached two unprotected peptides via CH(2)Cl handles to N4Py. In the presence of hydrogen peroxide, the iron(II) complex of this ligand (2a) generates an Fe(III)OOH intermediate (3a) that can oxidize a wide variety of organic compounds. Here, we describe the synthesis of 27, a N4Py derivative in which four three-carbon spacers have been introduced, and show that four copies of an unprotected, single-cysteine peptide can be coupled via a thioether linkage to the ligand. In addition, a divergent synthesis route to tetrabromide ligand 1b has also been developed, providing the opportunity to prepare alternative pentadentate ligands efficiently by four cross-coupling reactions on a single molecule. Also, two of the four bromides of 1b can be selectively addressed by magnesium-bromide exchange.