Prostaglandin Synthetase Activity Research Articles

ChemInform Abstract: 7‐Aroyl‐2,3‐dihydrobenzo[b]furan‐3‐carboxylic Acids and 7‐Benzoyl‐2,3‐ dihydrobenzo[b]thiophene‐3‐carboxylic Acids as Analgesic Agents.

AbstractDie im Titel genannten Verbindungen (IV) werden durch Friedel‐Crafts‐ Aroylierung der nach verschiedenen Methoden hergestellten Dihydrobenzo‐[b]furane bzw. ‐thiophene (II) in mäßigen Ausbeuten erhalten und die Derivate (V) hergestellt.

Reproduction in the freshwater gastropod,Helisoma: involvement of prostaglandin in egg production

Summary The introduction of nanogram quantities of prostaglandin E2 (PGE2) into the female genital opening of mated animals was found to increase both the number of egg masses produced and the number of eggs per mass. The intrahaemocoelic administration of a thousand-fold higher concentration of PGE2 was without effect, suggesting an indirect role of prostaglandin(s) in the regulation of egg production. Prostaglandin (PG) synthetase activity in both the bursa copulatrix and ovotestis varied with the reproductive status. High PG synthetase activity was present in virgin animals, and lower activity was found in mated animals. Prostaglandins produced by the bursa copulatrix are proposed here to be involved in the production of a matedness factor, which acts upon the brain to initiate or modulate egg production. PG produced by the ovotestis may be involved in ovulation. A model is proposed for the involvement of PG in the regulation of reproduction in Helisoma.

7-Aroyl-2,3-dihydrobenzo[b]furan-3-carboxylic acids and 7-benzoyl-2,3-dihydrobenzo[b]thiophene-3-carboxylic acids as analgesic agents.

The synthesis of a series of 7-aroyl-2,3-dihydrobenzo[b]furan-3-carboxylic acids and 7-benzoyl-2,3-dihydrobenzo[b]thiophene-3-carboxylic acids is described. The isomeric 4-benzoyl-1,3-dihydrobenzo[c]furan-1-carboxylic acid was also prepared. Compounds were evaluated for analgesic activity in the mouse phenyl-p-quinone-induced writhing test. Selected compounds were tested for their ability to produce gastric damage in fasted mice and for inhibition of prostaglandin synthetase activity in vitro. Zomepirac was used as a reference. Structure-activity relationships are discussed. One of the compounds, 7-benzoyl-5-chloro-2,3-dihydrobenzo[b]furan-3-carboxylic acid (2c), combined potent analgesic activity with low gastric irritancy.

Prostaglandin synthetase activity in layers of the kindey of young rats receiving polyene antibiotics

Prostaglandin synthetase activity in layers of the kindey of young rats receiving polyene antibiotics

Prostaglandin-synthetase activity in developing toad ovary—I. Detection and properties

Prostaglandin-synthetase activity has been measured in the microsomal fraction of developing toad (Bufo melanostictus) ovary using arachidonic acid as the substrate. Indomethacin (0.74μM) and aspirin (0.35μM) inhibit this activity. The activity is maximum in immature ovary and its level gradually decreases with maturity of the organ till the breeding season arrives, when it rises again. Time course study shows that the activityin vitro becomes steady after 3 min of incubation in all the cases, except the immature ones in which it sharply declines. Soluble supernatant was found to contain some inhibitory factor(s), which is partially inactivated by heating at 100°C for 5 min (∼ 43%). Intraperitoneal injection of equine luteinizing hormone stimulates this enzyme activity in the mature ovary during non-breeding season. This suggests that similar to mammalians prostaglandin-synthetase, the toad ovary enzyme is also regulated by luteinizing hormone

Histochemische Lokalisation der Aktivität der Prostaglandinsynthetase in einigen Organen bei Sehwein und Meerschweinchen

The activity of prostaglandin synthetase was studied according to the histochemical method of Janszen and Nugteren (1971), in author's own modification, in the lungs, arteries and parotid gland of the pig and in the same organs of the guinea pig. Additionally, the seminal vesicles of guinea pig were subject to investigation. A high activity of this enzyme has been found in the endothelial cells of the arteries in both species and a lower activity in the non-striated muscles of the artery wall. A high enzymatic activity has been also observed in the epithelial cells lining the bronchi and bronchioles of the lungs and in the ductus parotidicus of the parotid gland in both species, as well as in the epithelial cells of seminal vesicles in the guinea pig. A weaker, but distinct activity, has been observed in the cells of vesicles of pig parotid gland, and in the cells of stroma of guinea pig seminal vesicles.

An ex vivo method for evaluating prostaglandin synthetase activity in cortical slices of mouse brain.

The release of prostaglandin E2 (PGE2) from cortical slices of mice into incubation medium is followed for 3 h and compared to PGE2 levels in the corresponding slice. Immediately after decapitation, the rate of PGE2 released into the incubation medium is elevated and a steady low rate of spontaneous release is gained within 1-2 h of incubation. PGE2 synthesis and release is blocked in a dose-dependent manner by either indomethacin (3 X 10(-6) -3 X 10(-4) M) or flufenamic acid (2.6 X 10(-6) M) either when added in vitro or administered in vivo. Full recovery of PGE2 synthesis is reached after 3 h incubation of slices following in vivo administration of indomethacin. In vivo administration of flufenamic acid results in prolonged inhibition of PGE2 released in vitro. The inhibition of PGE2 released by indomethacin is also correlated with the slice PGE2 content. Administration of lipopolysaccharide (LPS), a known activator of phospholipase A2, results in a fivefold increase in PGE2 and a twofold increase in 6-keto-PGF1 alpha released into the medium. The release of thromboxane B2 is not affected by LPS.

ChemInform Abstract: PLANT‐DERIVED CATALYSTS AND PRECURSORS FOR USE IN PROSTAGLANDIN SYNTHESIS

AbstractArachidonsäure (I) läßt sich enzymatisch katalysiert mit O, zum Endoperoxid PGG, (II) oxidativ cyclisieren, das mit Glutathion zum Dihydroxyprostaglandin PGE, (I11) ge‐ öffnet wird; dieses liefert mit KOH das Prostaglandin PGB, (IV).

Ascorbate-dependent lipid peroxidation in the human placenta and fetal membranes.

The ascorbate-dependent lipid peroxidation in the microsomal fraction of at term placentas and fetal membranes were studied. In preliminary experiments, the optimum conditions for the measurement of this reaction were determined. Lipid peroxidation was significantly higher in the chorion and amnion compared to the placenta. In both fetal membranes, but not in the placenta, the reaction was enhanced by arachidonic acid and inhibited by indomethacin. The results indicate that the ascorbate-dependent lipid peroxidation in the fetal membranes is specific for prostaglandin synthetase activity and that these tissues are a major site of prostaglandin synthesis.

Plant‐derived catalysts and precursors for use in prostaglandin synthesis

AbstractArachidonic acid derivatives such as prostaglandins, thromboxanes, leukotrienes and prostacyclin have been recognized to have significant pharmaceutical potential. Presently they are not available commercially in large amounts because their low concentrations in living tissues and multiple asymmetric carbon centers make the cost of their extraction or chemical synthesis prohibitively expensive. However, the theoretical feasibility of the commercial production of such C‐20 compounds by means of fermentative and enzyme engineering processes that bypass animal sources entirely has been demonstrated. The precursor, arachidonic acid, is present in microorganisms adaptable to large‐scale fermentation. For the purpose of this study, a model describing changes in arachidonic acid production by the red alga,Porphyridium cruentum, in response to induced lipogenesis and variation of light intensity and temperature was developed. In addition, the demonstration that immobilized microsomes containing prostaglandin synthetase activity in a stable amphiphilic gel eliminates the need for the expensive and time‐consuming enzyme recovery methods used previously. Furthermore, the ability of a leguminous enzyme to catalyze the synthesis of prostaglandin indicates that low cost catalysts and precursors of plant origin are available for the synthesis of such compounds.

Endocrinology of human parturition: a review.

The existing data on the hormonal factors involved in human parturition indicate that the steroid hormones, progesterone and the oestrogens, play only a facilitatory role in the initiation of labour. A definite role for fetal adrenal steroids in this process has yet to be established, and they too may serve only a facilitating function. The stimulation of the uterine muscle during labour results from an interaction of oxytocin and prostaglandin (PG) F2 alpha. Recent evidence suggests that oxytocin is most important for the initial phase of labour, whereas increased synthesis of PGF2 alpha is essential for the progression of labour. The role of PGE2 remains unclear, but this PG may play an important role in the ripening of the cervix which in turn is essential for successful parturition. The finding of maximal oxytocin receptor concentrations in the myometrium in labour adds strong support to the notion that oxytocin is the trigger for uterine contractions. The factors which control oxytocin receptor formation are therefore important; this may be one of the processes where the steroids play a crucial role. Oxytocin is also one of the stimuli that increase uterine PG synthesis; the coupling of oxytocin receptor occupancy and PG synthetase activity in uterine tissues may be another crucial factor in the mechanism of labour. The formation of gap junctions between the myometrial cells also seems essential for the synchronization and progression of myometrial activity. We propose, therefore, that the co-ordinating of oxytocin receptor formation, PG synthesis and gap junction formation is a key to the initiation and maintenance of human labour. The fetus may fulfil such a co-ordinating role through its influence on placental oestrogen production, through mechanical distention of the uterus, and through its secretion of neuro-hypophysial hormones and other stimulators of PG synthesis.

The Role of 17β-Estradiol in the Recovery from Oviductal Prolapse in Layers

Plasma 17β-estradiol concentrations, thecal estrogen content, and uterine prostaglandin synthetase activity were measured in healthy and prolapsed hens as well as in layers that recovered after exposure to low intensity lighting (250 or 50 lx). The effect of estradiol benzoate injections (100 ng, 3 × per week) in hens exposed to high intensity light (>500 lx) was also studied.Prolapsed hens had significantly lower plasma 17β-estradiol concentrations (60 ± 12 pg/ml; mean ± SEM) than recovered (374 ± 40 pg/ml) or healthy hens (475 ± 45 pg/ml). Theca cells from recovered hens had a significantly higher content of 17β-estradiol (.7 ng/5 × 105 cells) than theca cells from normal or prolapsed birds (.3 ng/5 × 105 cells). Microsomes prepared from the uteri of prolapsed hens converted significantly less arachidonic acid to prostaglandin metabolites (4.4%) than did microsomes from healthy or recovered birds (9.0%).Treatment of prolapsed hens with estradiol benzoate resulted in 89% of the birds recovering within 3 weeks compared to a 4% recovery rate in the controls. We conclude that restoration of peripheral 17β-estradiol concentrations to normal levels was concomitant with recovery in prolapsed birds, and suggest that the estrogen exerts its effect by raising the level of prostaglandin synthetase activity in the uterus.

Enhancement of renal medulla prostaglandin synthetase activity by dexamethasone treatment in the rat

We studied in rats the effect of dexamethasone (2.5 mg/kg per week) on the conversion of radiolabeled arachidonic acid to prostaglandins by renal medulla slices, microsomes, and homogenates. The steroid did not affect the rate of conversion of arachidonic acid to prostaglandins by renal medulla slices, but significantly increased the rate of conversion by both the microsomes and the 10,000 × g supernatatant of renal medulla homogenates. We conclude (a) that dexamethasone treatment increases the activity of renal medulla prostaglandin synthetase measured in broken cells preparations, and (b) that such a change in enzyme activity is not manifested by augmentation of prostaglandin synthesis in renal medulla slices incubated with exogenous arachidonic acid.

Separate and combined use of verapamil, aspirin and captopril in experimental chronic pulmonary hypertension.

In Wistar rats, rendered pulmonary hypertensive by chronic confinement in normobaric "hypoxic cages", impairment of transmembrane transport of calcium by Verapamil and blockage of the action of Angiotensin I converting enzyme by Captopril when applied simultaneously did not show an additive effect in reducing the rise of pulmonary artery pressure and decreasing the augmentation of right ventricular mass. Similarly, the action of Verapamil together with decrease of prostaglandin synthetase activity by Aspirin showed no additive effect. Although in this way the results of the present study failed to give substantial support to the idea of the existence of several mediators of hypoxic pulmonary vasoconstriction, they by no means deny this possibility.

Pharmacological Properties of a New Anti-Inflammatory Compound, α-(3,5-Di-Tert-Butyl-4-Hydroxybenzylidene)-γ-Butyrolactone (KME-4), and Its Inhibitory Effects on Prostaglandin Synthetase and 5-Lipoxygenase

The pharmacological effects of a new anti-inflammatory compound, α-(3,5-di-tert-butyl-4-hydroxybenzylidene)-γ-butyrolactone (KME-4), and its inhibitory effects^ on arachidonate prostaglandin synthetase and 5-lipoxygenase activities were examined. KME-4 showed anti-inflammatory activity. It was less active than indomethacin, but more active than naproxen and ibuprofen in carrageenin-induced paw edema in rats; and it was less active than indomethacin, equ potent as naproxen, but more active than ibuprofen in granuloma formation in rats. The ulcerogenic activity of KME-4 was weaker than indomethacin and naproxen, but stronger than ibuprofen in starved rats. The ratio of UD50 stomach to ED30 carrageenin edema or to ED25 granuloma for KME-4 showed higher values than those of the reference drugs. KME-4 showed antipyretic activity in yeast-induced fever in rats. It also inhibited platelet aggregation induced by arachidonic acid and protected rabbits from arachidonic acid-induced death. Furthermore, KME-4 was found to be equipotent in inhibiting both prostaglandin synthetase and 5-lipoxygenase activities of rat basophilic leukemia cells, unlike indomethacin, naproxen and ibuprofen. It also inhibited the prostaglandin synthetase activity of bovine seminal vesicle. The present findings indicate that KME-4 may be a new type of anti-inflammatory drug with dual prostaglandin synthetase and 5-lipoxygenase inhibition.

The effect of oral administration of dipyrone on the capacity of blood platelets to synthesize thromboxane A2 in man.

Platelet aggregation and thromboxane A2 (TXA2) production induced by arachidonic acid and collagen were studied in 10 healthy volunteers prior to and at various times after the oral administration of a single dose of 1 g dipyrone. The plasma concentrations of four dipyrone metabolites were also determined. Dipyrone inhibited platelet aggregation and markedly decreased TXA2 synthesis induced by threshold concentrations of both agonists. Maximal inhibition was noted 1 hour after drug administration and in some subjects it lasted as long as 72 h. At all times the effect of the drug could be abolished by increasing the concentration of the agonist. This is consistant with a competitive inhibitory effect of dipyrone on prostaglandin synthetase activity. The mean plasma concentration of the main dipyrone metabolite methylaminoantipyrine at 1 h was 11 micrograms/ml. There was no correlation between individual plasma levels and the parameters of platelet function. At 24h the mean concentration of each of the metabolites studied was up to 1 microgram/ml, and these levels, too, did not correlate with the biological effect of the drug.

Prostaglandins in breast cancer: relationship to disease stage and hormone status.

Tissue prostaglandin (PG) content and production by human breast cancers were measured in 24 human mammary carcinoma specimens. The 5 compounds studied were PGE1, PGE2, PGF2 alpha, 6-keto-PGF1 alpha, and TXB2. The tissue content of all 5 compounds was higher in neoplastic tissue in comparison with the paired noncancerous breast tissue. However, microsomal PG synthetase activity in vitro in noncancerous and neoplastic breast tissue was comparable. Increased thromboxane formation was associated with three clinical variables--tumour size, axillary lymph node metastases and distant metastasis. A lesion negative for either oestrogen or progesterone receptor content tended to produce more TXB2 but lower PGE2 and 6-keto-PGF1 alpha. Results obtained in this pilot study may provide clues as to what direction future larger studies could take in the search for reliable prognostic indicators for breast cancer.

Cellular enzyme activity associated with tissue degradation following orthodontic tooth movement in man.

Enzyme histochemical techniques were used as markers of macrophage activity and differentiation in the periodontal tissues following orthodontic tooth movement in man. The enzymes studied included lactate dehydrogenase, glucose-6-phosphate dehydrogenase, succinic dehydrogenase, acid phosphatase and its tartrate resistant isoenzyme, arylsulfatase, aminopeptidase M and prostaglandin synthetase. Chloroacetyl esterase activity was studied in order to detect possible neutrophilic degrading activity. Intense activities of arylsulfatase and prostaglandin synthetase and a moderate activity of aminopeptidase M were found in cells degrading the hyaline zone. However, no activity of tartrate resistant acid phosphatase was found in these cells. Giant cells in contact with bone surfaces adjacent to the hyaline zone exhibited an intense activity of succinic dehydrogenase, tartrate resistant acid phosphatase and aminopeptidase M. Chloroacetyl esterase activity did not change following orthodontic treatment. The results indicate that macrophages in various stages of differentiation were responsible for the degradation of the hyaline zone and alveolar bone during orthodontic tooth movement. The enzymatic differences were probably due to the influence of the immediate cellular environment. Prostaglandin synthetase activity, which may be interpreted as a sign of prostaglandin secretion, was associated with the degradation of the hyaline zone in man.

Prostaglandin concentrations and prostaglandin synthetase activity in N-nitrosomethylurea-induced rat mammary adenocarcinoma

A comparison of tissue concentrations and biosynthesis of prostaglandin (PG)E 2, PGF 2α, 6-keto-PGF 1α (degradation production of PGI 2) and thromboxane (TX)B 2 (degradation product of TXA 2) was made in normal mammary glands obtained from virgin female Sprague-Dawley rats and in N-nitrosomethylurea (NMU)-induced mammary adenocarcinomas. The tissue concentrations ( ng g wet weight) of all 4 compounds were significantly higher in the NMU-induced tumor than in normal mammary tissue: PGE 2, 210 ± 37 vs 25 ± 6; PGE 2α, 287 ± 48 vs 23 ± 8; 6-keto-PGF 1α, 294 ± 42 vs 31 ± 8; and TXB 2, 260 ± 49 vs 27 ± 5 (mean ± S.E.M.). Microsomal prostaglandin synthetase activity in NMU-induced tumors was also significantly higher than in normal tissue for all but 6-keto-PGF 1α: PGE 2, 226 ± 16 vs 50 ± 9; PGF 2α, 28 ± 3 vs 4 ± 1; 6-keto-PGF 1α, 14 ± 2 vs 11 ± 2; and TXB 2, 17 ± 1 vs 10 ± 1 ng/mg protein (mean ± S.E.M.). There was no apparent relationship between either tumor size or age and the ability of microsomal enzyme to synthesize prostaglandins, although the content of prostaglandins extracted from tumor tissue was inversely related to the tumor size.

Inhibition of prostaglandin biosynthesis in renal (MDCK) cells by cAMP.

Cultured renal tubular cells (MDCK) have many of the biological properties of renal medullary tubular epithelial cells, including the ability to synthesize prostaglandin E2 (PGE2) as the major arachidonate metabolite. The hypothesis that adenosine 3',5'-cyclic monophosphate (cAMP) regulates prostaglandin synthesis in these cells was investigated by using cAMP, two degradation-resistant cAMP analogues [8-bromo-cAMP (8-BrcAMP) and N6,O2'-dibutyryl cAMP (DBcAMP)], and a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX). These agents inhibited basal-, calcium ionophore (A23187)-, or bradykinin-stimulated PGE2 biosynthesis by MDCK cells. The observed inhibition was dose- and time-dependent and could be reversed after 30 min of incubation in the absence of inhibitor. IBMX dose-dependently increased intracellular and extracellular cAMP levels by severalfold, suggesting that it was inhibiting prostaglandin biosynthesis by increasing cellular cAMP levels. Vasopressin, which stimulated cAMP levels by less than two-fold, did not inhibit prostaglandin synthesis. 8-BrcAMP and N6,O2'-DBcAMP inhibited A23187- or bradykinin-stimulated release of [3H]arachidonate from prelabeled cells, suggesting that cAMP inhibited acylhydrolase activity. Moreover, 8-BrcAMP also inhibited the conversion of exogenous arachidonate to PGE2 in intact cells and in a subcellular fraction containing prostaglandin synthetase activity, suggesting that cAMP inhibited cyclooxygenase and/or PGE2 isomerase activity. cAMP thus appears to regulate prostaglandin biosynthesis in MDCK cells by modulating the activity of two or more of the enzymes involved in the biosynthetic process.