esculetin and phenidone

Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids' eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development.

Topics: Animals; Dexamethasone; Eicosanoids; Female; Fertility; Host-Parasite Interactions; Male; Moths; Pyrazoles; Umbelliferones; Wasps

Influence of fungal species (conidia spores) on mortality of Pieris brassicae larvae differed when injected into the larvae. The effects of B. bassiana (ARSEF-1151) were expressed in a conidial dose-dependent manner on mortality of the larvae. An increased and faster mortality of the larvae followed B. bassiana (ARSEF-1151) infection when the spores were co-injected with the eicosanoid biosynthesis inhibitors (dexamethasone, naproxen, phenidone, esculetin). These compounds express different modes of action. These lethal effects were reversed when dexamethasone was injected with eicosanoid precursor arachidonic acid (20:4n-6). Nodulation is the predominant cellular reaction to bacterial and fungal injection in insects. Injection of each of five fungal species showed that nodulation intensity varies according to infecting fungal species. These findings support the idea that virulent effects of entomopathogenic, fungal species can be increased when P. brassicae immune systems are suppressed.

Topics: Animals; Butterflies; Dexamethasone; Eicosanoids; Immunity, Innate; Larva; Linear Models; Lipoxygenase Inhibitors; Mortality; Naproxen; Pyrazoles; Species Specificity; Spores, Fungal; Turkey; Umbelliferones

Inhibitors of cyclooxygenases prevent fever. The purpose of this study was to test the hypothesis that selective and dual inhibitors of the other enzyme systems of arachidonic acid oxygenation (i.e., lipoxygenase and epoxygenase) affect the time course or magnitude of fever in mice. Swiss Webster mice kept at 30 degreesC ambient temperature were implanted with biotelemeters to monitor body temperature. Fever was induced by intraperitoneal injection of lipopolysaccharide at doses from 10 micrograms/kg to 2.5 mg/kg. Phenidone (20-30 mg/kg ip), a dual lipoxygenase and cyclooxygenase inhibitor, prevented fever in these mice, but esculetin (1-10 mg/kg ip), a selective inhibitor of lipoxygenases, did not affect fever. Intramuscular injection of nordihydroguaiaretic acid (10-20 mg/kg), a dual lipoxygenase and epoxygenase inhibitor, as well as SKF-525A (5 mg/kg ip) and clotrimazole (20 mg/kg im), inhibitors of the cytochrome P-450/epoxygenase pathway, augmented fever in mice. Indomethacin (5 mg/kg ip), an inhibitor of cyclooxygenase, suppressed the exacerbation of fever due to clotrimazole, suggesting that the epoxygenase inhibitor-induced potentiation of fever in mice is a prostaglandin-mediated effect. From this study, we hypothesize that the cytochrome P-450/epoxygenase branch of the arachidonate cascade is involved in antipyresis and in controlling the upper limit of fever.

Topics: Animals; Antioxidants; Arachidonic Acid; Body Temperature; Body Temperature Regulation; Clotrimazole; Cyclooxygenase Inhibitors; Cytochrome P-450 Enzyme Inhibitors; Fever; Indomethacin; Lipopolysaccharides; Lipoxygenase Inhibitors; Male; Masoprocol; Mice; Proadifen; Pyrazoles; Time Factors; Umbelliferones

Recent evidence suggests that lipoxygenase (LO) metabolites inhibit renin production in vitro. However, the physiological significance of this effect has not been determined. This study examined the role of the LO pathway in the regulation of plasma renin concentration (PRC) in vivo. The acute administration of two structurally unrelated LO inhibitors, phenidone (30 and 60 mg/kg) and esculetin (60 mg/kg), resulted in suppression of platelet 12 hydroxyeicosatetraenoic acid (12HETE) production, reduction in systemic arterial pressure and a 2- to 3-fold increase in PRC. To determine whether the esculetin-induced increase in PRC was secondary to hypotension, esculetin was also administered to rats preinfused with a pressor dose of norepinephrine. In these acutely hypertensive rats, esculetin still induced a 2.5-fold increase in PRC, whereas blood pressure remained over 40 mm Hg above basal levels. Further, esculetin (10(-6)M) increased renin release in renal slices from 150 +/- 10 to 310 +/- 20 ng/ml.h (P < 0.05) and this rise was entirely blocked in the presence of 12HETE (10(-7)M; 130 +/- 40 ng/ml.h). In rats placed on high salt intake, 12HETE concentration in renal slices from the outer cortex was considerably higher than in renal slices from salt-restricted rats (116.5 +/- 15.7 vs. 65 +/- 12 pg/mg protein; P < 0.05). Chronic administration of the LO inhibitor phenidone also resulted in an increase of PRC, which was independent of changes in blood pressure. On either high salt (3.15%0 or low salt (0.05%) diet phenidone-treated rats had higher PRC levels than the respective control groups [high salt 9.7 +/- 3.5 vs. 1.9 +/- 1.4 ng/ml.h; P < 0.05; low salt 33.2 +/- 5.3 vs. 19.4 +/- 3.10 ng/ml.h; P < 0.05]. The finding that LO blockers are potent stimulators of PRC in vivo suggests the existence of a physiological tonic inhibition of renin secretion by LO products that is operative under a wide range of salt intake. High salt intake enhances this inhibitory tone by increasing renal cortical 12 LO activity and, in fact, normal suppression of PRC during high salt diet does not occur in LO-blocked animals. Thus, the LO pathway exerts a tonic inhibitory effect on renin release, which appears particularly important for renin suppression during high salt intake.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Arachidonate 12-Lipoxygenase; Blood Platelets; Enzyme Inhibitors; Hydroxyeicosatetraenoic Acids; Kidney; Lipoxygenase Inhibitors; Male; Norepinephrine; Pyrazoles; Rats; Rats, Sprague-Dawley; Renin; Sodium, Dietary; Umbelliferones

We have previously demonstrated that the lipoxygenase (LO) pathway has a specific role in the effect of angiotensin II (ANG II) on aldosterone secretion. To elucidate whether the LO pathway also participates in the vascular effects of ANG II, the nonselective LO inhibitor phenidone (PHE; 30 mg/kg) was administered to rats 1 h before graded dose ANG II infusion. PHE reduced the LO product 12-hydroxyeicosatetraenoic acid (12-HETE) in deendothelialized aortas by an average of 36% as determined by radiometric detection with high-performance liquid chromatography and radioimmunoassay methods. In parallel, the peak systolic pressor response to ANG II was lowered from 36.2 +/- 3.7 to 16.8 +/- 2.0 mmHg. The peak pressor responses to ANG II were also reduced by two other LO inhibitors, baicalein (30 mg/kg) and esculetin (60 mg/kg) (13.9 +/- 2.4 and 22.1 +/- 4.7 mmHg, respectively; P less than 0.01 compared with control rats for both), but not by the cyclooxygenase inhibitor indomethacin. The LO inhibitors baicalein (7.5 X 10(-5) M) and PHE (10(-4) M) markedly attenuated the in vitro contractile response to ANG II of femoral artery rings. In contrast, neither the in vivo nor in vitro constrictor responses to norepinephrine were affected by baicalein. Thus lipoxygenase blockade induces a direct and selective inhibition of ANG II-induced vasoconstriction. The LO pathway may have an important role in mediating the pressor effect of ANG II.

Topics: Angiotensin II; Animals; Blood Pressure; Diastole; Femoral Artery; Flavanones; Flavonoids; In Vitro Techniques; Indomethacin; Lipoxygenase Inhibitors; Male; Norepinephrine; Potassium Chloride; Pyrazoles; Rats; Rats, Inbred Strains; Reference Values; Systole; Umbelliferones; Vasoconstriction

When cultured malignant cells derived from rat gliomas (C6 and 9L) and human gliomas (A-172 and T98G) were treated for 4 hours with 1 to 80 microns nordihydroguaiaretic acid (NDGA) or 5,8,11,14-eicosatetraynoic acid (ETYA), a dose-dependent inhibition of deoxyribonucleic acid (DNA) synthesis occurred. In a series of three experiments for each cell line, 40 microM NDGA suppressed 3H-thymidine incorporation in the rat and human glioma lines to an average of less than 3.1% and 5.6% of control uptake (counts per minute), respectively. Incubation with a higher concentration of ETYA (80 microM) resulted in inhibition of rat and human DNA synthesis to less than 53% and 62% of control levels, respectively. This inhibition was not associated with any loss of cell viability, as judged by trypan blue exclusion studies. Prolonged incubation (for 72 hours) of the rat and human glioma cells with NDGA markedly decreased cell proliferation with no loss of cell viability. The inhibition of human glioma cell division by NDGA was rapidly reversible after incubation for 24 hours and at least partially reversible after incubation for 96 hours. It is concluded that the inhibitors of eicosanoid biosynthesis, NDGA and (to a lesser extent) ETYA, reduce in vitro cell proliferation in two glioma lines from both the rat and human. Since neither indomethacin nor acetylsalicylic acid altered DNA synthesis in these cell lines, this implicates the lipoxygenase products of arachidonic acid metabolism as important positive modulators in glioma cell division. These findings warrant further study in an in vivo system.

Topics: 5,8,11,14-Eicosatetraynoic Acid; Animals; Aspirin; Catechols; Cell Division; Cell Line; Cell Survival; DNA Replication; Glioma; Humans; Indomethacin; Kinetics; Lipoxygenase Inhibitors; Masoprocol; Pyrazoles; Rats; Tumor Cells, Cultured; Umbelliferones

The effects of Indomethacin, Esculetin, ETYA (4, 7, 10, 13-eicosatetraynoic acid, U53119), 3-amino-1-trifluoromethyl-7-phenyl-pyrazoline (BW 755C), Quercetin, Phenidone, and Nordihydroguaretic acid (NDGA) on the synthesis of 12-L hydroxyeicosatetraenoic acid (12-HETE) by human platelet 12-lipoxygenases were investigated. Except Indomethacin and Esculetin, all other drugs demonstrated significant inhibitory effect on 12-lipoxygenase activity. The rank order of potency for the inhibition of lipoxygenase in intact human platelets was ETYA greater than Quercetin greater than NDGA greater than Esculetin greater than Indomethacin. BW755C and Indomethacin were effective against platelet cyclooxygenase also. ETYA (U53119) was the most potent and selective inhibitor of platelet lipoxygenases. Results of our studies suggest that known lipoxygenase inhibitors display differential effects on platelet cyclooxygenase as well as membrane and cytosol associated lipoxygenases.

Topics: 4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; 5,8,11,14-Eicosatetraynoic Acid; Adult; Arachidonate Lipoxygenases; Blood Platelets; Cell Membrane; Cytosol; Humans; Indomethacin; Lipoxygenase Inhibitors; Masoprocol; Prostaglandin Antagonists; Pyrazoles; Quercetin; Substrate Specificity; Umbelliferones

Our previous studies had suggested a link between bile salt stimulation of colonic epithelial proliferation and the release and oxygenation of arachidonate via the lipoxygenase pathway. In the present study, we examined the role of reactive oxygen versus end products of arachidonate metabolism via the cyclooxygenase and lipoxygenase pathways in bile salt stimulation of rat colonic epithelial proliferation. Intracolonic instillation of 5 mM deoxycholate increased mucosal ornithine decarboxylase activity and [3H]thymidine incorporation into DNA. Responses to deoxycholate were abolished by the superoxide dismutase mimetic CuII (3,5 diisopropylsalicylic acid)2 (CuDIPS), and by phenidone or esculetin, which inhibit both lipoxygenase and cyclooxygenase activities. By contrast, indomethacin potentiated the response. Phenidone and esculetin suppressed deoxycholate-induced increases in prostaglandin E2 (PGE2), leukotriene B4 (LTB4), and 5, 12, and 15-hydroxyeicosatetraenoic acid (HETE), whereas CuDIPS had no effect. Indomethacin suppressed only PGE2. Deoxycholate (0.5-5 mM) increased superoxide dismutase sensitive chemiluminescence 2-10-fold and stimulated superoxide production as measured by cytochrome c reduction in colonic mucosal scrapings or crypt epithelium. Bile salt-induced increases in chemiluminescence were abolished by CuDIPS, phenidone, and esculetin, but not by indomethacin. Intracolonic generation of reactive oxygen by xanthine-xanthine oxidase increased colonic mucosal ornithine decarboxylase activity and [3H]thymidine incorporation into DNA approximately twofold. These effects were abolished by superoxide dismutase. The findings support a key role for reactive oxygen, rather than more distal products of either the lipoxygenase or cyclooxygenase pathways, in the stimulation of colonic mucosal proliferation by bile salts.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Bile Acids and Salts; Cell Cycle; Deoxycholic Acid; DNA; Female; Free Radicals; Indomethacin; Intestinal Mucosa; Lipoxygenase; Luminescent Measurements; Ornithine Decarboxylase; Oxygen; Prostaglandin-Endoperoxide Synthases; Pyrazoles; Rats; Salicylates; Superoxide Dismutase; Superoxides; Umbelliferones; Xanthine Oxidase

In this study we examined the effects of inhibitors of the lipoxygenase and cyclooxygenase pathways on mouse myoblast fusion. The fusion of cloned mouse myoblasts was markedly inhibited, in a dose-dependent manner, when cells were cultured in medium supplemented with either phenidone (1-phenyl-3-pyrazolidione) or BW755c (3-amino-1-(3-tri-fluoromethylphenyl)-2-pyrazoline), drugs which have been reported to inhibit lipoxygenase and cyclo-oxygenase activities. Fusion was also inhibited when these cells were cultured in medium supplemented with esculetin (6,7-dihydroxycoumarin) which has been reported to inhibit lipoxygenase activity. Removal of the above inhibitors resulted in a return to control levels of fusion. Fusion was not demonstrably inhibited with aspirin (acetylsalicylic acid) and only inhibited to a minor extent with indomethacin (1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid); both of these drugs are inhibitors of cyclo-exygenase activity.

Topics: 4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; Animals; Arachidonic Acid; Arachidonic Acids; Aspirin; Cell Fusion; Cells, Cultured; Cyclooxygenase Inhibitors; Indomethacin; Lipoxygenase Inhibitors; Mice; Muscles; Pyrazoles; Umbelliferones