Werner Skuballa

Pharmacological profile of a novel carbacyclin derivative with high metabolic stability and oral activity in the rat.

A novel carbacyclin derivative (16S)-13,14-dehydro-16,20-dimethyl-3-oxa-18,18,19,19-tetradehydro- 6a- carbaprostaglandin-I2 (3-oxa-analogue) has been synthesized in order to find chemically and metabolically stable prostacyclin-mimetics with a potency equal or even superior to PGI2. The 3-oxa-analogue was found to be stabilized against beta-oxidation, a main metabolic degradation step also for chemically stable PGI2-analogues. The compound is orally available and displays a long duration of 4.5-48 h of antiaggregatory and hypotensive action. The 3-oxa-analogue inhibits ADP-induced platelet aggregation with an IC50 of 3.0 nM. Following intravenous application the 3-oxa-analogue lowers diastolic blood pressure in a dose dependent manner, the ED20 being 0.1-0.2 micrograms/kg after injection and less than or equal to 0.05 micrograms/kg/min after infusion respectively. In vivo platelet aggregation is inhibited after i.v. infusion of the 3-oxa-analogue with an IC50 of 0.037 micrograms/kg/min. As compared to Iloprost, the 3-oxa-analogue is 5-12 fold more potent with respect to in vivo hypotensive and anti-aggregatory effects. The results of the present studies indicate that the 3-oxa-analogue has a pharmacological profile comparable to prostacyclin (PGI2) and Iloprost. Due to the fact that the 3-oxa-analogue is chemically and metabolically stable, long term oral treatment can be achieved in clinical conditions in which PGI2 and Iloprost have already been shown to be therapeutically useful principles.

Stable 9ß- or 11α-halogen-15-cyclohexyl-prostaglandins with high affinity to the PGD2-receptor

Various chemically stable prostaglandin analogues were studied for their affinity towards the PGD2-receptor in human platelet membranes in order to define the requirements for specific ligand binding to this receptor. On replacing the 11- or 9-hydroxyl groups of PGF2 alpha by an 11 alpha- or 9 beta-chloro- or fluoro atom, stable prostaglandin analogues were obtained, which showed high affinity towards the PGD2-receptor. The lower side chain consisted of a 15-cyclohexyl group or of the natural 15-n-pentyl group, other substitutents decreased the affinity substantially. The highest PGD2-mimetic activity with a relative affinity of 0.5 to the PGD2-receptor was found in 9-deoxy-9 beta-chloro-16,17,18,19,20-pentanor-15-cyclohexyl-PGF2 alpha (ZK 110 841, compound 16 in Table 1). ZK 110 841 is a chemically stable crystalline substance, which is orally active and which might thus turn out to be an interesting tool for the study of PGD2-receptor interactions. Some other prostaglandin as well as prostacyclin analogues with a 15-cyclohexyl or 15-n-pentyl group exhibited in addition to their known high affinity to the PGE2-receptor of human uterine membranes or the PGI2-receptor of human platelets also affinities to the PGD2-receptor. Generally, the receptor affinities correlate with the activities as stimulators of adenylate cyclase and inhibitors of thrombin induced elevation of cytoplasmic free calcium as well as their ability to inhibit ADP-induced platelet aggregation. The PGI2-character regarding the effector systems prevails in compounds with affinity to both the PGI2- and PGD2-receptor. Compounds which bind to the PGE2- and PGD2-receptor show a flat dose response curve regarding platelet activation suggesting a mixture of pro- and antiaggregatory properties within these molecules.

Chemistry of Stable Prostacyclin Analogues: Synthesis of Iloprost

The discovery of prostacyclin (PGI2) and its potent inhibitory action on platelet aggregation in 1976 by S. Moncada, R. Gryglewski, S. Bunting and J.R. Vane [1], has not only revolutionized concepts in cardiovascular research but has also made this important molecule a target for intensive biological and chemical research.

Synthesis of a chemically and metabolically stable and biologically potent PGD2-analogue

Abstract The metabolic labile α-chain of the PGD2-annlogue 2 (ZK 110841) can be stabilized by introduction of an β-oxygen-atom resulting in 3 (ZK 118182), which has a much higher and longer lasting biological activity on oral application in rats. The synthetic methodology for the synthesis of 3-oxa Z -Δ5,6-prostaglandins will be discussed.

Synthesis of 6,9-homo-prostacyclin a stable prostacyclin analog☆

Abstract A stable prostacyclin analog was synthesized starting from an intermediate of the Corey prostaglandin synthesis.

The identification of a small molecule inhibitor that specifically reduces T cell-mediated adaptive but not LPS-mediated innate immunity by T cell membrane–monocyte contact bioassay

Proinflammatory cytokines such as TNFalpha and IL-1beta are produced in lesional skin of chronic plaque psoriasis patients, and at other sites of chronic inflammation such as arthritic joints. They play vital roles in maintaining inflammation. It has recently been suggested that activated T cell contact-mediated monocyte activation, leading to the production of proinflammatory cytokines, contributes to the pathogenesis of psoriasis and other chronic inflammatory diseases such as psoriatic arthritis and rheumatoid arthritis. Using a T cell membrane-monocyte contact bioassay, we have identified small molecule antagonists that differentially block anti-CD3/anti-CD28 activated T cell-mediated, but not LPS-stimulated, TNFalpha production from monocytes. We selected several kinase inhibitors from the Berlex/Schering kinase library and tested the effect of these compounds in blocking TNFalpha production in the T cell membrane-monocyte contact bioassay. We have demonstrated that one compound BLX-1, from a p38 MAP kinase inhibitor project, inhibited T cell-mediated TNFalpha production from monocytes by about 80%, without any effect on TNFalpha production from LPS-stimulated monocytes. Other BLX-1 analogs showed 32-83% inhibition of TNFalpha production with LPS stimulation as compared to almost 100% inhibition of T cell-mediated TNFalpha production. In contrast, PKC inhibitors BLX-5, Go6983, and Ro-31-8220, inhibited TNFalpha production from both activated T cell membrane- and LPS-stimulated monocytes to the same extent (in the range of 50-100% inhibition). Therefore, the activated T cell membrane-monocyte contact bioassay can be used to screen small molecule antagonists that specifically target adaptive but not LPS-mediated innate immunity. Small molecule TNFalpha inhibitors interfering specifically with activated T cell contact-mediated TNFalpha production from monocytes, but not with LPS-mediated TNFalpha production of myeloid cells, are predicted to have an improved side-effect profile and thus may provide more favorable therapeutics for the treatment of T cell-mediated inflammatory diseases.

Synthesis of potent 6-oxo and 9-fluoro-PGE1-derivatives and their biological properties

Abstract The synthesis of the biologically potent 6-oxo-PGE 1 analog 18 and its 9-fluoro-derivative 21 as well as their biological data are presented.

Synthesis of prostacyclin analogs stabilized by acceptor substituents at the 5-position

The chemically labile natural prostacyclin (PGI2) 1 can be stabilized by introduction of an electron withdrawing 5-substituent like cyano, formyl, carboxy or alkoxycarbonyl resulting e.g. in 5-cyano-16-methyl-prostacyclin (nileprost) 6, a potent ulcer healing agent.

Novel prostanoid thromboxane A2 agonists

The chemistry and biology of novel TXA2(TP)-receptor agonists based on the prostanoid skeleton is described and structure-activity-relationships are discussed. One compound,(5Z,13E), (9R,15R)-9-fluoro-15-hydroxy-16-phenoxy-17,18,19,20-tetranor- 5,13-prostadienoic acid (33), was identified which is 10 times more potent than the standard TP-receptor against U 46619.

In vitro effects of PGF2α and a metabolically stable derivative on 20α-hydroxysteroid-dehydrogenase activity in corpora lutea isolated from pseudopregnant rat ovaries

Abstract Single intact corpora lutea were isolated from pseudopregnant rat ovaries stimulated with PMSG and HCG. The activity of 20α-hydroxvsteroid-dehydrogenase (20α-OH-SDH) was measured at various stages of pseudopregnancy. The influence of PGF2α or a metabolically stable PGF2α-derivative on this enzyme in vitro was assessed. 20α-OH-SDH activity was low from day 6 to 8, started to rise on day 10 and reached a maximum on day 14 after administration of HCG. The enzyme could be stimulated by the PGF2α -derivative on day 10 and 11 but not on day 6, 8, when basal enzyme activity was still very low or on 12 and 14 of pseudopregnancy when the enzyme had already reached maximal levels. PGF2 or its derivative had no effect on enzyme activity in α cytosolic fraction indicating that particulate cell constituents were required for this process. PGE2 as well as cycloheximide (an inhibitor of protein biosynthesis) were without influence on enzyme stimulation. dB-cAMP but not dB-cGMP decreased enzyme activity. Ca2+-ions were required for the stimulation of 20α-OH-SDH activity. It is concluded that PGF2 or its stable derivative may modulate ovarian steroid Metabolism by acute stimulation of luteal 20α-OH-SDH.