The effects of synthetic prostaglandin analogs on canine hepatic bile flow.

The synthetic prostaglandin analogs 16, 16-dimethyl PGF2 alpha and 16, 16-dimethyl PGE2 were administered to dogs with chronic biliary and gastric fistulas. The effects of 16, 16 diMePGF2 alpha and 16, 16 diMePGE2 were evaluated on bile flow and composition and bile adenosine 3', 5' monophosphate (cyclic AMP) secretion. 16, 16 diMePGF2 alpha in doses of 0.125 and 0.25 microgram-kg-min significantly increased hepatic bile flow. The choleresis was characterized by increased chloride and bicarbonate secretion. Measurement by radioimmunoassay of bile cyclic AMP concentration demonstrated no evident increase in bile cyclic AMP secretion associated with the choleresis produced by 16, 16 diMePGF2 alpha. The administration of 16, 16 diMePGE2 in a dose range 0.01 to 1.0 microgram-kg-min did not significantly alter bile flow rates or composition. Bile erythritol-14C clearance, a measure of canalicular bile flow, was significantly increased by PGF2 alpha but not by 16, 16-dimethyl PGF2 alpha, suggesting that the mechanism of action of PGF2 alpha in stimulating hepatic bile flow may be different from that involved in 16, 16-dimethyl PGF2 alpha choleresis. The results of this study indicate that the synthetic PGF2 alpha analog produces a choleretic response not mediated by adenylate cyclase and associated with increased chloride and bicarbonate secretion.     

High performance liquid chromatography of synthetic analogs of prostaglandin E

High-performance liquid chromatography was used for separation, identification and purification of synthetic analogues of prostaglandin E, about 30 various samples being analysed. Basing on the data obtained, recommendation are given on the preparative HPLC separation (up to 300 mg scale) of structural isomers and epimers of synthetic prostaglandins.     

Some biological effects of prostaglandin endoperoxide analogs.

The effects of two methano-epoxy analogs of the prostaglandin endoperoxides PGG₂ and PGH₂ were tested on human platelets and rabbit aorta strips. One of these analogs, 9α, 11α-methano-epoxy-15- hydroxy-prosta-5, 13-dienoic acid, was 3.7 times more potent than the endoperoxide, PGG₂, as aggregating agent and was 6.2 times more active than PGH₂ in eliciting contractions of the isolated rabbit aorta. The analog initiated the platelet release reaction, but was less active than the endoperoxide in this respect. Furthermore, the release of ¹⁴C-serotonin induced by this analog was inhibited by indomethacin, which indicated that generation of endoperoxide was required.The corresponding 9α, 11α, epoxy-methano-analog was less active than the 9α, 11α, methano-epoxy analog in the test systems employed.     

The synthesis of prostaglandin analogs containing hydroxycyclohexenyl rings

The synthesis of prostaglandin analogs incorporating the 3-hydroxycyclohexenyl moiety in place of the natural C₁₃–C₂₀ sidechain has been accomplished via copper-assisted conjugate addition of the cycloalkenyllithium to the cyclopentenone intermediates , and .     

Synthesis of macrolide prostaglandin analogs

Prostaglandin analogs of the E- and F₂α-functional type, which are constrined to conformations in which the side-chains are close in space and specifically aligned in the terminal portions by covalent bonding, have been synthesized. These analogs are 1, (ω-1)-macrolides. The syntheses proceed from aldehyde intermediate I $\text{via}$ the Emmon's condensation with dimethyl n-(dimethyl-t-butyl-silyloxy) 2-oxoalkylphosphonate anions (IIa or b). The macrolide closures were performed using 2,2′-dipyridyl disulfide. For the synthesis of 9-ketoprostaglandin macrolides, a free 9-hydroxy is available for oxidation after macrolide closure, so long as the 9-position is protected as the acetate rather than benzoate. Chiroptical data revealed that the conformations of the macrolide prostaglandins are unchanged (relative to the natural uncosntrained prostaglandins) in the vicinity of the five-membered ring and the allyl alcohol unit by the formation of the macrolide linkage.     

Evaluation of the role of the F prostaglandins in canine bile flow

Prostaglandin F_2α (PGF_2α) has been shown to be an effective stimulant of hepatic bile flow producing a specific chloride rich bile. Subsequent evaluation by radioimmunoassay has shown that prostaglandin F compounds are present in relatively large amounts in canine hepatic bile. This study evaluates the effect of PGF_2α administration and of prostaglandin synthetase inhibition by aspirin and indomethacin on bile flow and radioimmunoassayable prostaglandin F (iPGF) secretion. Chronic, canine bile fistula preparations were utilized and the enterohepatic circulation was maintained by intravenous bile salts. Bile volume and composition were evaluated by standard techniques as well as bile PGF concentration by radioimmunoassay during bile salt infusion and during bile salt and PGF_2α, aspirin and indomethacin infusion in varying doses. Both aspirin and PGF_2α were potent stimulatns of hepatic bile flow with aspirin producing a chloride rich bile similar to that produced by PGF_2α. PGF_2α produced dose related increases in bile iPGF concentration and output indicating that as the systemic concentration increases during infusion of PGF_2α the lipid appears in bile. Aspirin in the highest dose administered, decreased iPGF concentration in bile while output was unchanged. Indomethacin was ineffectual in consistently altering bile flow or iPGF secretion. This study demonstrates that iPGF is present in canine bile, that its concentration can be altered by prostaglandin infusion while prostaglandin synthetase inhibition has minimal effects on bile iPGF secretion.     

The synthesis of prostaglandin analogs containing hydroxycyclohexenyl rings.

The synthesis of prostaglandin analogs incorporating the 3-hydroxycyclohexenyl moiety in place of the natural C13-C20 side-chain has been accomplished via copper-assisted conjugate addition of the cycloalkenyllithium 2 to the cyclopentenous intermediates 4, 7 and 10.     

Synthesis of some aromatic prostaglandin analogs

Some aromatic prostaglandin analogs, having a benzene (2a, 2b) and a dimethoxybenzene (1) ring in place of the cyclopentane moiety, have been synthesized. The key intermediates in the syntheses were lactols 9 and 5, which were elaborated to the final products via two olefination reactions. Compound 2b was twice as potent as phenylbutazone and nine times as potent as aspirin in inhibiting prostaglandin synthetase activity.     

Synthesis of some aromatic prostaglandin analogs

Some aromatic prostaglandin analogs, having a benzene (2a, 2b) and a dimethoxybenzene (1) ring in place of the cyclopentane moiety, have been synthesized. The key intermediates in the syntheses were lactols 9 and 5, which were elaborated to the final products via two olefination reactions. Compound 2b was twice as potent as phenylbutazone and nine times as potent as aspirin in inhibiting prostaglandin synthetase activity.     

The effects of 11-methyl 16,16 dimethyl prostaglandin E2 on canine gastric acid secretion

11-Methyl 16,16 Dimethyl Prostaglandin E₂ (TM-PGE₂) at peak effectiveness inhibited acid output stimulated submaximally by histamine in the dog by 95 and 84% when administered by the intravenous and oral routes, respectively. Inhibition of secretion was maintained for hours following intravenous administration while with the oral route, secretory inhibition was still present at the end of two hours after administration of the drug. The degree of inhibition of acid secretion caused by TM-PGE₂, its duration of action and the lack of side effects observed following administration of this drug makes it a suitable compound for evaluation as an anti-secretory agent in man.     

Short-term effects of thalidomide analogs on hepatic glycogen and nitric oxide in endotoxin-challenged rats

Hepatic glycogen metabolism is altered by nitric oxide (NO) during endotoxic shock. Thalidomide analogs immunomodulate the endotoxin-induced cytokines which regulate the NO release. We analyzed the short-term effects of some thalidomide analogs on the hepatic glycogen store and on the plasma and hepatic NO in an acute model of endotoxic challenge in rat. An endotoxin dose selection was performed. Rats received vehicle, thalidomide or analogs orally and, two hours after last dose, they were injected with endotoxin (5 mg/kg). Animals were sacrificed 2 h after challenge. Liver glycogen was quantified by the anthrone technique. Plasma and hepatic NO was determined by Griess reagent and HPLC. Hepatic interferon-gamma, a NO co-inducer, was measured by ELISA. Endotoxin caused inverse dose-dependent effects on plasma NO and on glycogen.Thalidomide analogs showed short-term regulatory effects on glycogen, some of them increased it. Plasma NO was almost unaffected by analogs but hepatic NO was strikingly modulated. Analogs slightly up-regulated the liver interferon-gamma and two of them increased it significantly. Thalidomide analogs may be used as a pharmacological tool due to their short-term regulatory effects on glycogen and NO during endotoxic shock. Drugs that increase glycogen may improve liver injury in early sepsis.     

Inhibitory effects of bile acids and synthetic farnesoid X receptor agonists on rotavirus replication

Rotaviruses (group A rotaviruses) are the most important cause of severe gastroenteritis in infants and children worldwide. Currently, an antiviral drug is not available and information on therapeutic targets for antiviral development is limited for rotavirus infection. Previously, it was shown that lipid homeostasis is important in rotavirus replication. Since farnesoid X receptor (FXR) and its natural ligands bile acids (such as chenodeoxycholic acid [CDCA]) play major roles in cholesterol and lipid homeostasis, we examined the effects of bile acids and synthetic FXR agonists on rotavirus replication in association with cellular lipid levels. In a mouse model of rotavirus infection, effects of oral administration of CDCA on fecal rotavirus shedding were investigated. The results demonstrate the following. First, the intracellular contents of triglycerides were significantly increased by rotavirus infection. Second, CDCA, deoxycholic acid (DCA), and other synthetic FXR agonists, such as GW4064, significantly reduced rotavirus replication in cell culture in a dose-dependent manner. The reduction of virus replication correlated positively with activation of the FXR pathway and reduction of cellular triglyceride contents (r(2) = 0.95). Third, oral administration of CDCA significantly reduced fecal virus shedding in mice (P < 0.05). We conclude that bile acids and FXR agonists play important roles in the suppression of rotavirus replication. The inhibition mechanism is proposed to be the downregulation of lipid synthesis induced by rotavirus infection.     

Biological activities of prostaglandin H1 analogs

The influences of epoxymethano and epoxycarbonyl analogs of PGH1 on washed rabbit platelets, isolated smooth muscles and perfused heart preparations were investigated. On washed rabbit platelets, 11,9-epoxymethano and 11,9-epoxycarbonyl PGH1 produced a platelet aggregation whereas 9,11-epoxymethano and 9,11-epoxycarbonyl PGH1 produced an inhibition of arachidonic acid-induced platelet aggregation. On iso-ated rabbit thoracic aorta strips, 9,11-epoxycarbonyl PGH1 showed strong contracting activity (5 times as active as 11,9-epoxymethano PGH2 and 31 times as active as PGH2). All the analogs of PGH1 caused contraction of guinea pig tracheal muscle and caused an increase of perfusion pressure in guinea pig heart, though 11,9-epoxymethano and epoxycarbonyl PGH1 were far more active than 9,11-epoxymethano and epoxycarbonyl PGH1. Differences in biological activities between 11,9-epoxymethano and epoxycarbonyl PGH1 indicate that the orientation of functional groups at C9 and C11 influences biological activities.     

Metabolism of synthetic inositol trisphosphate analogs

A series of synthetic analogs was employed to explore structure-activity relationships in the metabolism of the second messenger inositol trisphosphate (IP3) in vascular tissue. Cytosolic IP3-5-phosphatase activity was purified approximately 240-fold from bovine aorta. All synthetic analogs tested were apparent competitive inhibitors of the 5-phosphatase activity. The order of potency was DL-1,3,4,5-IP3 greater than D-1,4,5-IP3 greater than DL-1,3,4-IP3 greater than L-1,4,5-IP3 greater than 1,3,5-IP3 greater than DL-6-methoxy-1,4,5-IP3 greater than DL-2,4,5-IP3 greater than DL-1,2,4-cyclohexane-P3. The least potent analogs had Ki values only 11 times higher than the apparent Km of the substrate D-1,4,5-[3H]IP3. However, only three synthetic compounds, DL-1,3,4,5-IP4, D-1,4,5-IP3, and DL-2,4,5-IP3, could serve as substrates for the 5-phosphatase. IP3 kinase activity in the same tissue exhibited considerably more selectivity with respect to inhibition by IP3 analogs. D-1,4,5-IP3 was about 30 times more potent than DL-1,3,4,5-IP4 and 100-1000 times more potent than the other compounds tested. The function of the IP3 receptor was evaluated by measuring labeled calcium mobilization in permeabilized bovine aortic smooth muscle cells in culture. While all analogs tested were full agonists, vast differences in potency were observed. D-1,4,5-IP3 was about 30 times more potent than DL-2,4,5-IP3 and 100-2000 times more potent than the other analogs tested. The results suggest that IP3-5-phosphatase activity is relatively nonselective in the binding of inositol polyphosphates, while IP3 kinase activity and the IP3 receptor exhibit great selectivity in the recognition of these compounds.     

Assay of kinins by their effects on canine femoral blood flow.

In pentobarbital anesthetized dogs, close arterial injections of bradykinin and kallidin elicit a dose related increase in femoral blood flow. Treatment with the kininase inhibitor BPP9alpha augments the femoral blood flow responses to bradykinin and kallidin by five and threefold respectively. The sensitivity of the preparation permits the detection of 0.5-1 ng of either bradykinin or kallidin in untreated dogs and as little as 0.1 ng of kinin peptides in animals receiving BPP9alpha. This sensitivity and the steepness of the dose response curves make this procedure suitable for the assay of kinins.     

The synthesis and biological activity of prostaglandin analogs containing spirocyclic rings

The synthesis of prostaglandin analogs ( - ) incorporating the spiro[3.3]hept-2-yl moeity in place of the natural C₁₆–C₂₀ side-chain has been accomplished via reaction of the mixed cuprate with cyclopentenone intermediates , , and . The biological activities of these new analogs are discussed.