Exploration of amino alcohol derivatives as novel, potent, and highly selective sphingosine-1-phosphate receptor subtype-1 agonists.

In pursuit of a potent and highly selective sphingosine-1-phosphate receptor agonists with an improved in vivo conversion of the precursor to the active phospho-drug, we have utilized previously reported phenylamide and phenylimidazole scaffolds to identify a selectivity enhancing moiety (SEM) and selectivity enhancing orientation (SEO) within both pharmacophores. SEM and SEO have allowed for over 100 to 500-fold improvement in selectivity for S1P receptor subtype 1 over subtype 3. Utility of SEM and SEO and further SAR study allowed for discovery of a potent and selective preclinical candidate PPI-4955 (21b) with an excellent in vivo potency and dose responsiveness and markedly improved overall in vivo pharmacodynamic properties upon oral administration.

Design, synthesis and selection of DNA-encoded small-molecule libraries.

Biochemical combinatorial techniques such as phage display, RNA display and oligonucleotide aptamers have proven to be reliable methods for generation of ligands to protein targets. Adapting these techniques to small synthetic molecules has been a long-sought goal. We report the synthesis and interrogation of an 800-million-member DNA-encoded library in which small molecules are covalently attached to an encoding oligonucleotide. The library was assembled by a combination of chemical and enzymatic synthesis, and interrogated by affinity selection. We describe methods for the selection and deconvolution of the chemical display library, and the discovery of inhibitors for two enzymes: Aurora A kinase and p38 MAP kinase.

Synthesis and evaluation of arylalkoxy- and biarylalkoxy-phenylamide and phenylimidazoles as potent and selective sphingosine-1-phosphate receptor subtype-1 agonists.

In pursuit of potent and selective sphingosine-1-phosphate receptor agonists, we have utilized previously reported phenylamide and phenylimidazole scaffolds to explore extensive side-chain modifications to generate new molecular entities. A number of designed molecules demonstrate good selectivity and excellent in vitro and in vivo potency in both mouse and rat models. Oral administration of the lead molecule 11c (PPI-4667) demonstrated potent and dose-responsive lymphopenia.

Synthesis and evaluation of alkoxy-phenylamides and alkoxy-phenylimidazoles as potent sphingosine-1-phosphate receptor subtype-1 agonists.

In the design of potent and selective sphingosine-1-phosphate receptor agonists, we were able to identify two series of molecules based on phenylamide and phenylimidazole analogs of FTY-720. Several designed molecules in these scaffolds have demonstrated selectivity for S1P receptor subtype 1 versus 3 and excellent in vivo activity in mouse. Two molecules PPI-4621 (4b) and PPI-4691 (10a), demonstrated dose responsive lymphopenia, when administered orally.

Solution structures of cyclic melanocortin agonists and antagonists by NMR.

The melanocortin receptors are involved in many physiological functions, including pigmentation, sexual function, feeding behavior, and energy homeostasis, making them potential targets for drugs to treat obesity, sexual dysfunction, etc. Understanding the conformational basis of the receptor-ligand interactions is crucial to the design of potent and selective ligands for these receptors. The solution structures of the cyclic melanocortin agonists, partial agonist, and antagonists MTII, VJH085, SHU9119, MK5, and MK9 were determined by two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy at pH 4.5 and 25 degrees C in water (90% H(2)O/10% D(2)O). The overall backbone structures of these cyclic alpha-melanocyte-stimulating hormone (alpha-MSH) analogues around the message sequence (His(6)-D-Phe(7)/D-Nal(2')(7)-Arg(8)-Trp(9)) were similar and reasonably well defined. beta-Turns spanning His(6) and D-Phe(7)/D-Nal(2')(7) were identified in all analogues, and an amphiphilic molecular surface was obtained for the message sequence residues in most structures within the NMR ensembles. The beta-turn, which most closely resembles a type II beta-turn, leads to stacking between the aromatic rings of His(6) and D-Phe(7) in MTII and VJH085. However, no aromatic stacking between His(6) and D-Nal(2')(7) was found in structures of the D-Nal(2')(7)-containing analogues. The difference in the side-chain dispositions of His(6) and D-Nal(2')(7) may be responsible for the reduced potency or antagonist activity of the D-Nal(2')(7)-containing analogues. In addition, our results suggest that the side-chain orientations may also modulate the receptor selectivity. The information found in this study will be useful for the further design of ligands for melanocortin receptors.

Novel cyclic templates of alpha-MSH give highly selective and potent antagonists/agonists for human melanocortin-3/4 receptors.

In an effort to develop highly selective and potent agonists and/or antagonists for the hMC3 and hMC4 receptors, a new approach involving the use of linker arms and a backbone to side chain cyclization strategy was employed. Three key analogues were identified to have the required selectivity and potency at the hMC3 or hMC4 receptors, implicated to play pivotal roles in energy homeostasis and other biological effects. The novel cyclic peptide (O)C-CH(2)-CH(2)-C(O)-c-[His(6)-D-Phe(7)-Arg(8)-Trp(9)-Lys(10)]-NH(2) (1) was found to be a highly selective and potent agonist of the hMC4 receptor. Structure-activity studies have shown that replacing the succinyl linker arm of 1 by an o-phthalic acid group and substituting a D-Nal(2')(7) residue in place of D-Phe(7) results in a potent antagonist 7 at the hMC4 receptor. Furthermore, increasing the 23-membered lactam ring of 1 by one carbon atom (succinyl --> glutaric acid linker) gives a highly selective and potent antagonist 9 for the hMC3 receptor. Analogues 1, 7, and 9 therefore represent the first examples of a class of cyclic melanotropin ligands with high selectivity and defined biological activities at the physiologically important hMC3 and hMC4 receptors.