The origin of the anomalous H8 chemical shifts observed in 'H-NMR spectra of oligonucleotides cross-linked at a GpG sequence with c i .~-[ P t ( N H~)~1~ ' has been investigated and clarified. The main contributions that distinguish the H8 resonances of the two platinum-ligating guanines from other GH8 signals and from each other are: (a) the inductive effect of platinum binding which we have recently quantified as a downfield shift of 0.48 f 0.07 ppm (M. H. Fouchet, D. Lemaire, J. Kozelka and J.-C. Chottard, unpublished results); (b) the ring-current effect of one GpG guanine on the H8 resonance of the other guanine, which is negative (shielding) for the 5'-H8 and positive (deshielding) for the 3'-H8 in single-stranded adducts, but has the opposite sign in double-stranded adducts; (c) a deshielding polarization effect of the phosphate 5' to the GpG unit. The different signs of the ringcurrent effects in single-stranded and double-stranded oligonucleotides originate from the orientation of the guanines in the cis-[Pt(NH3),(Gua),]~ ' moiety (Gua, guanine), which is left-handed helicoidal in single strands and right-handed helicoidal in double strands. In the platinated dinucleotides (cis-[Pt(NH,),(GpG)]+, cis-[Pt(NH3),{d(GpG)}]+ and cis-[Pt(NH,),{d(pCpG))I), the guanines assume either the left-handed or the right-handed arrangement, depending on the sugar moiety (ribose or deoxyribose), protonation state at N1 and, in the solid state, on crystal forces. This work shows that chemical shifts contain valuable structural information which is complementary to that extracted from correlated spectroscopy and nuclear Overhauser spectroscopy data.The antitumor drug cis-diamminedichloroplatinum(I1) binds to DNA, the preferential binding sites being GpG and ApG sequences [l]. These dinucleotides form, with the platinum residue, a macrochelate in which the two N7 atoms are covalently bound to platinum. NMR studies on oligonucleotides (as models for DNA) have been used in order to elucidate the structural changes imposed on DNA by platinum binding [l]. In these studies, spectral changes were interpreted in terms of structural deformation of the helicoidal oligonucleotide geometry. Unfortunately, the most spectacular and easily detectable spectral changes observed upon platination, large shifts of some proton and phosphorus resonances, could only be interpreted to a limited extent [2-41, because the origin of these shifts is not easy to discern.The most striking change in the 'H-NMR spectra of oligonucleotides upon platinum binding to GpG or ApG sequences is a downfield shift of the GpG and ApG H8 protons. These downfield shifts are different in single-stranded and double-stranded adducts, and for single \Wands the\ are dependent on whether or not the GpG or ApG dinuclcotide is preceeded by a free phosphate group or by another nucleotide (Table 1). There is no obvious relationship between thechemical shift (6) values for HX and the adduct types listed in Table 1, yet they must contain valuable structural information. In this w...

Optimization of the screening hit 1 led to the identification of novel 1,5-naphthyridine aminothiazole and pyrazole derivatives, which are potent and selective inhibitors of the transforming growth factor-beta type I receptor, ALK5. Compounds 15 and 19, which inhibited ALK5 autophosphorylation with IC50 = 6 and 4 nM, respectively, showed potent activities in both binding and cellular assays and exhibited selectivity over p38 mitogen-activated protein kinase. The X-ray crystal structure of 19 in complex with human ALK5 is described, confirming the binding mode proposed from docking studies.

The peroxisome proliferator activated receptors PPARalpha, PPARgamma, and PPARdelta are ligand-activated transcription factors that play a key role in lipid homeostasis. The fibrates raise circulating levels of high-density lipoprotein cholesterol and lower levels of triglycerides in part through their activity as PPARalpha agonists; however, the low potency and restricted selectivity of the fibrates may limit their efficacy, and it would be desirable to develop more potent and selective PPARalpha agonists. Modification of the selective PPARdelta agonist 1 (GW501516) so as to incorporate the 2-aryl-2-methylpropionic acid group of the fibrates led to a marked shift in potency and selectivity toward PPARalpha agonism. Optimization of the series gave 25a, which shows EC50 = 4 nM on PPARalpha and at least 500-fold selectivity versus PPARdelta and PPARgamma. Compound 25a (GW590735) has been progressed to clinical trials for the treatment of diseases of lipid imbalance.

RIP1 kinase regulates necroptosis and inflammation and may play an important role in contributing to a variety of human pathologies, including inflammatory and neurological diseases. Currently, RIP1 kinase inhibitors have advanced into early clinical trials for evaluation in inflammatory diseases such as psoriasis, rheumatoid arthritis, and ulcerative colitis and neurological diseases such as amyotrophic lateral sclerosis and Alzheimer's disease. In this paper, we report on the design of potent and highly selective dihydropyrazole (DHP) RIP1 kinase inhibitors starting from a high-throughput screen and the leadoptimization of this series from a lead with minimal rat oral exposure to the identification of dihydropyrazole 77 with good pharmacokinetic profiles in multiple species. Additionally, we identified a potent murine RIP1 kinase inhibitor 76 as a valuable in vivo tool molecule suitable for evaluating the role of RIP1 kinase in chronic models of disease. DHP 76 showed efficacy in mouse models of both multiple sclerosis and human retinitis pigmentosa.