SAR-studies of γ-secretase modulators with PPARγ-agonistic and 5-lipoxygenase-inhibitory activity for Alzheimer's disease.

We present the design, synthesis and biological evaluation of compounds containing a 2-(benzylidene)hexanoic acid scaffold as multi-target directed γ-secretase-modulators. Broad structural variations were undertaken to elucidate the structure-activity-relationships at the 5-position of the aromatic core. Compound 13 showed the most potent activity profile with IC50 values of 0.79µM (Aß42), 0.3µM (5-lipoxygenase) and an EC50 value of 4.64µM for PPARγ-activation. This derivative is the first compound exhibiting low micromolar to nanomolar activities for these three targets. Combining γ-secretase-modulation, PPARγ-agonism and inhibition of 5-lipoxygenase in one compound could be a novel disease-modifying multi-target-strategy for Alzheimer's disease to concurrently address the causative amyloid pathology and secondary pathologies like chronic brain inflammation.

Vanillin-derived antiproliferative compounds influence Plk1 activity.

We synthesized a series of vanillin-derived compounds and analyzed them in HeLa cells for their effects on the proliferation of cancer cells. The molecules are derivatives of the lead compound SBE13, a potent inhibitor of the inactive conformation of human polo-like kinase 1 (Plk1). Some of the new designs were able to inhibit cancer cell proliferation to a similar extent as the lead structure. Two of the compounds ((({4-[(6-chloropyridin-3-yl)methoxy]-3-methoxyphenyl}methyl)(pyridin-4-ylmethyl)amine) and (({4-[(4-chlorophenyl)methoxy]-3-methoxyphenyl}methyl)(pyridin-4-ylmethyl)amine)) were much stronger in their capacity to reduce HeLa cell proliferation and turned out to potently induce apoptosis and reduce Plk1 kinase activity in vitro.

Understanding the antagonism of retinoblastoma protein dephosphorylation by PNUTS provides insights into the PP1 regulatory code.

The serine/threonine protein phosphatase 1 (PP1) dephosphorylates hundreds of key biological targets by associating with nearly 200 regulatory proteins to form highly specific holoenzymes. However, how these proteins direct PP1 specificity and the ability to predict how these PP1 interacting proteins bind PP1 from sequence alone is still missing. PP1 nuclear targeting subunit (PNUTS) is a PP1 targeting protein that, with PP1, plays a central role in the nucleus, where it regulates chromatin decondensation, RNA processing, and the phosphorylation state of fundamental cell cycle proteins, including the retinoblastoma protein (Rb), p53, and MDM2. The molecular function of PNUTS in these processes is completely unknown. Here, we show that PNUTS, which is intrinsically disordered in its free form, interacts strongly with PP1 in a highly extended manner. Unexpectedly, PNUTS blocks one of PP1's substrate binding grooves while leaving the active site accessible. This interaction site, which we have named the arginine site, allowed us to define unique PP1 binding motifs, which advances our ability to predict how more than a quarter of the known PP1 regulators bind PP1. Additionally, the structure shows how PNUTS inhibits the PP1-mediated dephosphorylation of critical substrates, especially Rb, by blocking their binding sites on PP1, insights that are providing strategies for selectively enhancing Rb activity.

SAR-study on a new class of imidazo[1,2-a]pyridine-based inhibitors of 5-lipoxygenase.

A novel class of 5-lipoxygenase (5-LO) inhibitors characterized by a central imidazo[1,2-a]pyridine scaffold, a cyclohexyl moiety and an aromatic system, is presented. This scaffold was identified in a virtual screening study and exhibits promising inhibitory potential on the 5-LO. Here, we investigate the structure-activity relationships of this compound class. With N-cyclohexyl-6-methyl-2-(4-morpholinophenyl)imidazo[1,2-a]pyridine-3-amine (14), we identified a potent 5-LO inhibitor (IC(50)=0.16µM (intact cells) and 0.1µM (cell-free)), which may possess potential as an effective lead compound intervening with inflammatory diseases and certain types of cancer.

SAR studies of acidic dual γ-secretase/PPARγ modulators.

A novel set of dual γ-secretase/PPARγ modulators characterized by a 2-benzyl hexanoic acid scaffold is presented. Synthetic efforts were focused on the variation of the substitution pattern of the central benzene. Finally, we obtained a new class of 2,5-disubstituted 2-benzylidene hexanoic acid derivatives, which act as dual γ-secretase/PPARγ modulators in the low micromolar range. We have explored broad SAR and successfully improved the dual pharmacological activity and the selectivity profile against potential off-targets such as NOTCH and COX. Compound 17 showed an IC(50) Aß42=2.4 µM and an EC(50) PPARγ=7.2 µM and could be a valuable tool to further evaluate the concept of dual γ-secretase/PPARγ modulators in animal models of Alzheimer's disease.

Discovery and biological evaluation of a novel class of dual microsomal prostaglandin E2 synthase-1/5-lipoxygenase inhibitors based on 2-[(4,6-diphenethoxypyrimidin-2-yl)thio]hexanoic acid.

Various inflammatory diseases are associated with the excessive formation of leukotrienes (LTs) and prostaglandins (PGs). Herein, we present a novel class of dual inhibitors of 5-lipoxygenase (5-LO) and microsomal prostaglandin E(2) synthase-1 (mPGES-1), key enzymes in the formation of LTs and PGE(2), respectively. On the basis of the structure of 2-[(4,6-diphenethoxypyrimidin-2-yl)thio]hexanoic acid (1), we performed a detailed SAR analysis, and mechanistic studies were carried out to elucidate the mode of 5-LO inhibition. Interestingly, the pyrimidine ring including the thioether of 1 could be replaced by a simple benzyl or a benzylidene moiety yielding a novel series of bioactive 2-benzylidene- and 2-benzylhexanoic acids exemplified by 2-(2,3-diphenethoxybenzylidene)hexanoic acid, 29 (IC(50) 5-LO = 0.8 µM; mPGES-1 = 1.1 µM). Importantly, none of the novel bioactive derivatives strongly inhibited cyclooxygenase activities. Together, we provide novel promising lead compounds for the treatment of inflammatory diseases valuable for further investigations in vivo.

A novel class of dual mPGES-1/5-LO inhibitors based on the α-naphthyl pirinixic acid scaffold.

Dual inhibition of microsomal prostaglandin E(2) synthase-1 (mPGES-1) and 5-lipoxygenase (5-LO) represents a promising strategy in the development of novel anti-inflammatory drugs targeting the arachidonic acid cascade. Herein, a class of α-naphthyl pirinixic acids is characterized as dual mPGES-1/5-LO inhibitors. Systematic structural variation was focused on the lipophilic backbone of the scaffold and yielded detailed structure-activity relationships (SAR) with compound 16 (IC(50) mPGES-1=0.94 µM; IC(50) 5-LO=0.1 µM) showing the most favorable in vitro pharmacological profile.

Design, synthesis, and biological evaluation of a novel class of gamma-secretase modulators with PPARgamma activity.

We present a novel class of dual modulators of gamma-secretase and peroxisome proliferator-activated receptor gamma (PPARgamma) based on the structure of 2-(bis(phenethoxy)pyrimidine-2-ylthio)hexanoic acid 8 (IC(50)(Abeta42) = 22.8 microM, EC(50)(PPARgamma) = 8.3 microM). The modulation of both targets with approved drugs (i.e., amyloid-beta 42 (Abeta42)-lowering NSAIDs for gamma-secretase and glitazones for PPARgamma) has demonstrated beneficial effects in in vitro and in vivo models of Alzheimer's disease (AD). However, although NSAIDs and PPARgamma agonists share similar structural features, no druglike compounds with dual activities as gamma-secretase modulators (GSMs) and PPARgamma agonists have been designed so far. On the basis of our initial lead structure 8, we present the structure-activity relationships (SARs) of broad structural variations. A significant improvement was reached by the introduction of p-trifluoromethyl substituents at the phenyl residues yielding compound 16 (IC(50)(Abeta42) = 6.0 microM, EC(50)(PPARgamma) = 11.0 microM) and the replacement of the two phenyl residues of 8 by cyclohexyl yielding compound 22 (IC(50)(Abeta42) = 5.1 microM, EC(50)(PPARgamma) = 6.6 microM).