Discovery of ONO-8590580: A novel, potent and selective GABAA α5 negative allosteric modulator for the treatment of cognitive disorders.

The identification and SAR development of a series of negative allosteric modulators of the GABAA α5 receptor is described. This novel series of compounds was optimised to provide analogues with high GABAA α5 binding affinity, high α5 negative allosteric modulatory activity, good functional subtype selectivity and low microsomal turnover, culminating in identification of ONO-8590580.

Efficacy and immunomodulatory actions of ONO-4641, a novel selective agonist for sphingosine 1-phosphate receptors 1 and 5, in preclinical models of multiple sclerosis.

ONO-4641 is a next-generation sphingosine 1-phosphate (S1P) receptor agonist selective for S1P receptors 1 and 5. The objective of the study was to characterize the immunomodulatory effects of ONO-4641 using preclinical data. ONO-4641 was tested in both in-vitro pharmacological studies as well as in-vivo models of transient or relapsing-remitting experimental autoimmune encephalomyelitis (EAE). In vitro, ONO-4641 showed highly potent agonistic activities versus S1P receptors 1 and 5 [half maximal effective concentration (EC(50) ) values of 0·0273 and 0·334 nM, respectively], and had profound S1P receptor 1 down-regulating effects on the cell membrane. ONO-4641 decreased peripheral blood lymphocyte counts in rats by inhibiting lymphocyte egress from secondary lymphoid tissues. In a rat experimental autoimmune encephalomyelitis (EAE) model, ONO-4641 suppressed the onset of disease and inhibited lymphocyte infiltration into the spinal cord in a dose-dependent manner at doses of 0·03 and 0·1 mg/kg. Furthermore, ONO-4641 prevented relapse of disease in a non-obese diabetic mouse model of relapsing-remitting EAE. These observations suggest that ONO-4641 may provide therapeutic benefits in the treatment of multiple sclerosis.

Potent, low-molecular-weight non-peptide inhibitors of malarial aspartyl protease plasmepsin II.

A number of single-digit nanomolar, low-molecular-weight plasmepsin II aspartyl protease inhibitors have been identified using combinatorial chemistry and structure-based design. By identifying multiple, small-molecule inhibitors using the parallel synthesis of several focused libraries, it was possible to select for compounds with desirable characteristics including enzyme specificity and minimal binding to serum proteins. The best inhibitors identified have Ki's of 2-10 nM, molecular weights between 594 and 650 Da, between 3- and 15-fold selectivity toward plasmepsin II over cathepsin D, the most closely related human protease, good calculated log P values (2.86-4.56), and no apparent binding to human serum albumin at 1 mg/mL in an in vitro assay. These compounds represent the most potent non-peptide plasmepsin II inhibitors reported to date.

Effect of a new bombesin receptor antagonist, (E)-alkene bombesin isostere, on amylase release from rat pancreatic acini.

The short-chain pseudopeptide, [D-Phe6, Leu13 psi (CH2NH)Leu14]bombesin(6-14) (RDI), is reported to be a potent antagonist of bombesin, and development of this type of compound has greatly contributed to the investigation of biological actions of bombesin and its related peptides. We recently synthesized (E)-alkene bombesin isostere by replacing the peptide bond with an (E)-double bond: [D-Phe6, Leu13 psi [(E)CH = CH]Leu14] bombesin(6-14) (EABI). The present study examined the effect of EABI on amylase release from rat pancreatic acini. EABI showed no agonistic activity at concentrations up to 1 microM, and RBI showed slight agonistic activity at concentrations > 10 nM. EABI caused a dose-dependent inhibition of amylase release stimulated by 0.1 nM bombesin, with an IC50 of 6.7 +/- 1.7 nM, and induced almost-complete inhibition at 0.3 microM. RDI caused a dose-dependent inhibition of amylase release, with an IC50 of 68.7 +/- 16 nM. EABI caused a parallel and rightward shift of the entire dose-response curve of bombesin-stimulated amylase release, and the degree of the shift was dependent on the concentrations of EABI. EABI (100 nM) and RDI (100 nM) inhibited amylase releases stimulated by gastrin-releasing peptide (1 nM) and neuromedin-C (1 nM). In contrast, amylase release stimulated by cholecystokinin octapeptide (0.1 nM), carbachol (10 microM), vasoactive intestinal peptide (1 nM), and gastrin-17 (10 nM) was not inhibited by EABI and RDI. The results indicate that EABI is a potent and specific bombesin receptor antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of structural modulation on biological activity of bombesin analogues with (E)-alkene bond.

The specific bombesin receptor antagonist, (E)-alkene bombesin isostere (EABI-1), [D-Phe6,Leu13psi[(E)CH=CH]Leu14]bombesin(6-14) is a potent antagonist in terms of inhibition of bombesin-stimulated amylase release from rat pancreatic acini. This study examined the effects of EABI-1 (L-L diastereomer) and three novel bombesin analogues on amylase release in rat pancreatic acini. EABI-2 is a L-D diastereomer of EABI-1. EABI-3 is an analogue, of which leucine at position 13 of EABI-1 was replaced with valine. EABI-4 is a L-D diastereomer of EABI-3 (L-L). The order of agonist potency was EABI-2>EABI-3>EABI-4. EABI-1 showed no agonist activity at concentrations up to 100nM. On the other hand, all of four analogues had antagonist activity. The order of antagonist potency was EABI-1>EABI-3>EABI-4>EABI-2. EABI-1 was a complete antagonist, EABI-2 and EABI-3 were partial agonists, and EABI-4 had a weak agonist effect. The present study provides a useful information on the future development of peptide analogues for anticancer agents and biological tools for investigating actions of bombesin family peptides.

Novel low molecular weight spirodiketopiperazine derivatives potently inhibit R5 HIV-1 infection through their antagonistic effects on CCR5.

Novel low molecular weight spirodiketopiperazine derivatives which potently inhibit R5 human immunodeficiency virus type 1 (HIV-1) infection through their antagonistic effects on CCR5 were identified. One such compound E913 (M(r) 484) specifically blocked the binding of macrophage inflammatory protein-1alpha (MIP-1alpha) to CCR5 (IC(50) 0.002 microm) and MIP-1alpha-elicited cellular Ca(2+) mobilization (IC(50) approximately 0.02 microm). E913 potently inhibited the replication of laboratory and primary R5 HIV-1 strains as well as various multidrug-resistant monocyte/macrophage tropic (R5) HIV-1 at IC(50) values of 0.03 to 0.06 microm. E913 was inactive against T cell tropic (X4) HIV-1; however, when combined with a CXCR4 antagonist AMD-3100, E913 potently and synergistically inhibited the replication of dualtropic HIV-1 and a 50:50 mixture of R5 and X4 HIV-1. Antagonism in anti-HIV-1 activity was not seen when E913 was combined with the reverse transcriptase inhibitor zidovudine or protease inhibitors. E913 proved to compete with the binding of antibodies to CCR5 which recognize the C-terminal half of the second extracellular loop (ECL2B) of CCR5. E913 and its analogs are acid-resistant and orally bioavailable in rodents. These data warrant that spirodiketopiperazine derivatives be further developed as potential therapeutics for HIV-1 infection.