Discovery of a 1-Methyl-3,4-dihydronaphthalene-Based Sphingosine-1-Phosphate (S1P) Receptor Agonist Ceralifimod (ONO-4641). A S1P1 and S1P5 Selective Agonist for the Treatment of Autoimmune Diseases.

The discovery of 1-({6-[(2-methoxy-4-propylbenzyl)oxy]-1-methyl-3,4-dihydronaphthalen-2-yl}methyl)azetidine-3-carboxylic acid 13n (ceralifimod, ONO-4641), a sphingosine-1-phosphate (S1P) receptor agonist selective for S1P1 and S1P5, is described. While it has been revealed that the modulation of the S1P1 receptor is an effective way to treat autoimmune diseases such as relapsing-remitting multiple sclerosis (RRMS), it was also reported that activation of the S1P3 receptor is implicated in some undesirable effects. We carried out a structure-activity relationship (SAR) study of hit compound 6 with an amino acid moiety in the hydrophilic head region. Following identification of a lead compound with a dihydronaphthalene central core by inducing conformational constraint, optimization of the lipophilic tail region led to the discovery of 13n as a clinical candidate that exhibited >30 000-fold selectivity for S1P1 over S1P3 and was potent in a peripheral lymphocyte lowering (PLL) test in mice (ED50 = 0.029 mg/kg, 24 h after oral dosing).

K+ excretion: the other purpose for puddling behavior in Japanese Papilio butterflies.

To elucidate the purpose of butterfly puddling, we measured the amounts of Na+, K+, Ca2+, and Mg2+ that were absorbed or excreted during puddling by male Japanese Papilio butterflies through a urine test. All of the butterflies that sipped water with a Na+ concentration of 13 mM absorbed Na+ and excreted K+, although certain butterflies that sipped solutions with high concentrations of Na+ excreted Na+. According to the Na+ concentrations observed in naturally occurring water sources, water with a Na+ concentration of up to 10 mM appears to be optimal for the health of male Japanese Papilio butterflies. The molar ratio of K+ to Na+ observed in leaves was 43.94 and that observed in flower nectars was 10.93. The Na+ amount in 100 g of host plant leaves ranged from 2.11 to 16.40 mg, and the amount in 100 g of flower nectar ranged from 1.24 to 108.21 mg. Differences in host plants did not explain the differences in the frequency of puddling observed for different Japanese Papilio species. The amounts of Na+, K+, Ca2+, and Mg2+ in the meconium of both male and female butterflies were also measured, and both males and females excreted more K+ than the other three ions. Thus, the fluid that was excreted by butterflies at emergence also had a role in the excretion of the excessive K+ in their bodies. The quantities of Na+ and K+ observed in butterfly eggs were approximately 0.50 µg and 4.15 µg, respectively; thus, female butterflies required more K+ than male butterflies. Therefore, female butterflies did not puddle to excrete K+. In conclusion, the purpose of puddling for male Papilio butterflies is not only to absorb Na+ to correct deficiencies but also to excrete excessive K+.

Japanese Papilio butterflies puddle using Na+ detected by contact chemosensilla in the proboscis.

Many butterflies acquire nutrients from non-nectar sources such as puddles. To better understand how male Papilio butterflies identify suitable sites for puddling, we used behavioral and electrophysiological methods to examine the responses of Japanese Papilio butterflies to Na(+), K(+), Ca(2+), and Mg(2+). Based on behavioral analyses, these butterflies preferred a 10-mM Na(+) solution to K(+), Ca(2+), and Mg(2+) solutions of the same concentration and among a tested range of 1 mM to 1 M NaCl. We also measured the ion concentrations of solutions sampled from puddling sites in the field. Na(+) concentrations of the samples were up to 6 mM, slightly lower than that preferred by butterflies in the behavioral experiments. Butterflies that sipped the 10 mM Na(+) solution from the experimental trays did not continue to puddle on the ground. Additionally, butterflies puddled at sites where the concentrations of K(+), Ca(2+), and/or Mg(2+) were higher than that of Na(+). This suggests that K(+), Ca(2+), and Mg(2+) do not interfere with the detection of Na(+) by the Papilio butterfly. Using an electrophysiological method, tip recordings, receptor neurons in contact chemosensilla inside the proboscis evoked regularly firing impulses to 1, 10, and 100 mM NaCl solutions but not to CaCl(2) or MgCl(2). The dose-response patterns to the NaCl solutions were different among the neurons, which were classified into three types. These results showed that Japanese Papilio butterflies puddle using Na(+) detected by the contact chemosensilla in the proboscis, which measure its concentration.

Prevention of GVHD and graft rejection by a new S1P receptor agonist, W-061, in rat small bowel transplantation.

BACKGROUND: In small bowel transplantation (SBTx), inhibition of both graft-versus-host disease (GVHD) and allograft rejection is necessary. METHODS: We investigated the potency of a new sphingosine-1-phosphate receptor agonist, W-061, for these two immune responses in SBTx. W-061 has a completely different molecular structure from FTY720. Heterotopic SBTx was performed from Wistar-Furth (WF) into (WF×ACI) F1 rats as a GVHD model or F1 to WF rats as a rejection model. Recipients were orally given 3 mg/kg/day W-061 for 14 days after SBTx. Recipient survival, body weight, histopathology, lymphocyte subpopulations, and the cytokine profile were evaluated. RESULTS: W-061 treatment significantly prolonged graft survival over 100 days in four out of six recipients in the GVHD group and over 60 days in three out of six recipients in the rejection group. W-061 strongly inhibited GVHD and rejection as seen histopathologically in comparison with untreated control rats. W-061 caused a significant reduction in donor-derived T cells in target organs and infiltrating T cells in allografts by promoting these cells to home into the secondary lymphoid tissues and sequestrating those cells there. W-061 significantly decreased production of interferon-γ in target organs and allografts. CONCLUSION: Therefore, these data suggest that W-061 has considerable potential as a new therapeutic immunosuppressant in patients with SBTx.

Structure-activity relationship studies of S1P agonists with a dihydronaphthalene scaffold.

Structure-activity relationship (SAR) of sphingosine-1-phosphate receptor agonists with a dihydronaphthalene scaffold was investigated. Compound 1 was modified to improve S1P(1) agonistic activity and in vivo peripheral lymphocyte lowering (PLL) activity without impairing selectivity over S1P(3) agonistic activity. A detailed SAR study of the terminal lipophilic part revealed that the introduction of substituents on the propylene linker and the terminal benzene ring influences in vitro and PLL activities. Compound 6n bearing a (S)-methyl group at the 2-position on the propylene linker and chlorine at the para-position on the terminal benzene ring showed potent hS1P(1) agonistic activity with excellent selectivity over hS1P(3) and in vivo PLL activity in mice.

Therapeutic effects of novel sphingosine-1-phosphate receptor agonist W-061 in murine DSS colitis.

Although IL-17 is a pro-inflammatory cytokine reportedly involved in various autoimmune inflammatory disorders, its role remains unclear in murine models of colitis. Acute colitis was induced by 2.5% dextran sodium sulfate (DSS) treatment for 5 days. A novel sphingosine-1-phosphate receptor agonist W-061, a prototype of ONO-4641, was orally administered daily, and histopathological analysis was performed on the colon. The number of lymphocytes and their cytokine production were also evaluated in spleen, mesenteric lymph node, Peyer's patch and lamina propria of the colon. Daily administration of W-061 resulted in improvement of DSS-induced colitis, and significantly reduced the number of CD4+ T cells in the colonic lamina propria. Numbers of both Th17 and Th1 cells were reduced by W-061 treatment. W-061, however, had no influence on the number of Treg cells in lamina propria. Thus, Th17 and Th1 cells in lamina propria were thought to be the key subsets in the pathogenesis of DSS-induced colitis. In conclusion, W-061 may be a novel therapeutic strategy to ameliorate acute aggravation of inflammatory bowel diseases.

Discovery of S1P agonists with a dihydronaphthalene scaffold.

Structure-activity relationship of sphingosine-1-phosphate receptor agonists was examined. Cinnamyl derivative 1 was modified to improve S1P(1) agonistic activity as well as selectivity over S1P(3) agonistic activity. Dihydronaphthalene derivative 10d was identified as a potent S1P(1) receptor agonist with high selectivity against S1P(3) and enhanced efficacy in lowering peripheral lymphocyte counts in mice.

Structure-activity relationship studies of sphingosine-1-phosphate receptor agonists with N-cinnamyl-ß-alanine moiety.

Structure-activity relationship of sphingosine-1-phosphate receptor agonist was examined. In terms of reducing the flexibility of molecule, hit compound 1 was modified to improve S1P(1) agonistic activity as well as selectivity over S1P(3) agonistic activity. Novel S1P agonists with cinnamyl scaffold or 1,2,5,6-tetrahydropyridine scaffold were identified.