Oceanapia magna Sponge Presents Dual Effect on the Gastrointestinal Motility of Rodents: In Vitro and In Vivo Assays.

Oceanapia magna Santos-Neto, Nascimento, Cavalcanti and Pinheiro sponges are distributed across tropical worldwide seas. Some studies of marine products have shown interesting activities in smooth muscle models. Hence, we assessed the effect of the ethanolic extract of Oceanapia magna. (OC-EtOH) on acute toxicity and gastrointestinal motility (in vitro and in vivo) in rodent models. On guinea pig ileum, OC-EtOH induced a concentration dependent contraction on basal tonus, which was not inhibited by atropine, but in the presence of pyrilamine or verapamil, the effect was antagonized. Contrastingly, on KCl- or histamine-induced contractions, OC-EtOH presented a transient contraction followed by a concentration-dependent relaxation. Moreover, OC-EtOH presented a relaxant profile on cumulative curves to CaCl2 and tonic contraction induced by S-(-)-BayK8644, through Cav blockade. The acute toxicity assay showed that OC-EtOH (2,000 mg/kg, p.o.) did not present any sign of toxicity in female mice. Additionally, OC-EtOH presented antidiarrheal effect in mice, increased the intestinal normal transit and reduced the castor oil-induced intestinal transit. Thus, OC-EtOH presented a dual effect on guinea pig ileum promoting contraction through activation of H1 and CaV, and relaxation through CaV blockade, besides the effect on upper gastrointestinal transit in mice, showing a potential medicinal use of this sponge in intestinal diseases such as diarrhea.

Tocolytic action and underlying mechanism of galetin 3,6-dimethyl ether on rat uterus.

BACKGROUND: Galetin 3,6-dimethyl ether (FGAL) is a flavonoid isolated from aerial parts of Piptadenia stipulacea. Previously, FGAL was shown to inhibit both carbachol- and oxytocin-induced phasic contractions in the rat uterus, which was more potent with oxytocin. Thus, in this study, we aimed to investigate the tocolytic action mechanism of FGAL on the rat uterus. METHODS: Segments of rat uterus ileum were suspended in organ bath containing modified Locke-Ringer solution at 32 °C, bubbled with carbogen mixture under a resting tension of 1 g. Isotonic contractions were registered using kymographs and isometric contractions using force transducer. RESULTS: FGAL was more potent in relaxing uterus pre-contracted with oxytocin than with KCl. Additionally, FGAL shifted oxytocin-induced cumulative contractions curves to the right in a non-parallel manner, with Emax reduction, indicating a pseudo-irreversible noncompetitive antagonism of oxytocin receptors (OTR) or a downstream pathway target. Moreover, FGAL shifted CaCl2-induced cumulative contraction curves to the right in a non-parallel manner in depolarizing medium, nominally without Ca2+, with Emax reduction, suggesting the inhibition of Ca2+ influx through CaV. The relaxant potency of FGAL was reduced by CsCl, a non-selective K+ channel blocker, suggesting positive modulation of these channels. Furthermore, in presence of apamin, 4-aminopyridine, glibenclamide or 1 mM TEA+, the relaxant potency of FGAL was attenuated, indicating the participation of SKCa, KV, KATP and highlighting BKCa. Aminophylline, a non-selective phosphodiesterase (PDE) blocker, did not affect the FGAL relaxant potency, excluding the modulation of cyclic nucleotide PDEs pathway by FGAL. CONCLUSION: Tocolytic effect of FGAL on rat uterus occurs by pseudo-irreversible noncompetitive antagonism of OTR and activation of K+ channels, primarily BKCa, leading to calcium influx reduction through CaV.

Involvement of ß adrenergic receptors in spasmolytic effect of caulerpine on guinea pig ileum.

Previously, we demonstrated that caulerpine has spasmolytic effect on guinea pig ileum. The aim of this study was to investigate pathways of its spasmolytic action. We test caulerpine against phasic contractions induced by carbachol in the circular layer of guinea pig ileum and this alkaloid did not inhibit these contractions, indicating that caulerpine did not interfering with the mobilisation of Ca2+ from intracellular stores. Additionally, the spasmolytic effect of caulerpine did not involve K+ channels. Furthermore, we observed that α2-adrenergic receptors were not involved in the spasmolytic effect of caulerpine, since the relaxation curve induced by caulerpine was not shifted in the presence of yohimbine (α2-adrenergic antagonist). However, in the presence of propranolol (ß-adrenergic antagonist), the relaxation curve induced by caulerpine was right-shifted, resulting in a fivefold increase in EC50. Thus, a possible mechanism for the spasmolytic action of caulerpine is the activation of ß-adrenergic receptors.

Assessment of mechanisms involved in antinociception produced by the alkaloid caulerpine.

In previous works we showed that oral administration of caulerpine, a bisindole alkaloid isolated from algae of the genus Caulerpa, produced antinociception when assessed in chemical and thermal models of nociception. In this study, we evaluated the possible mechanism of action of this alkaloid in mice, using the writhing test. The antinociceptive effect of caulerpine was not affected by intraperitoneal (i.p.) pretreatment of mice with naloxone, flumazenil, l-arginine or atropine, thus discounting the involvement of the opioid, GABAergic, l-arginine-nitric oxide and (muscarinic) cholinergic pathways, respectively. In contrast, i.p. pretreatment with yohimbine, an α2-adrenoceptor antagonist, or tropisetron, a 5-HT3 antagonist, significantly blocked caulerpine-induced antinociception. These results suggest that caulerpine exerts its antinociceptive effect in the writhing test via pathways involving α2-adrenoceptors and 5-HT3 receptors. In summary, this alkaloid could be of interest in the development of new dual-action analgesic drugs.

Mechanisms underlying the relaxant effect of Galetin 3,6- dimethyl ether, from Piptadenia stipulacea (Benth.) Ducke, on guinea-pig trachea.

Galetin 3,6-dimethyl ether (FGAL), a flavonoid from the aerial parts of Piptadenia stipulacea (Benth.) Ducke, was found to exert a relaxant effect on carbachol (CCh)-pre-contracted guinea-pig trachea. Based on cumulative concentration-response curves to CCh, FGAL antagonized muscarinic receptors pseudo-irreversibly and noncompetitively, since it inhibited and shifted these curves towards higher concentrations in a nonparallel manner. In addition, FGAL was more potent in relaxing contractions induced by 18 mM as compared to 60 mM KCl (pD2 = 5:50 ±0:36 and 4.80 ±0.07, respectively), indicating the participation of K+ channels. In the presence of 10 mM tetraethylammonium (TEA+) chloride, a nonselective K+ channel blocker, the relaxant potency of FGAL was reduced (from pD2 = 5:12 ±0:07 to 4.87 ±0.02). Among several selective blockers of K+ channel subtypes, only apamin, an SKCa (small-conductance Ca2+-activated K+ channels) blocker, attenuated the relaxant potency of FGAL (pD2 = 4:85±0:06), suggesting SKCa activation. FGAL was equipotent in relaxing trachea contracted by 60 mM KCl (pD2 =4:80 ±0:07) or 10-6 M CCh (pD2 = 5:02 ±0:07), suggesting CaV (voltage-gated calcium channel), but not ROCs (receptor-operated calcium channels) participation. Furthermore, aminophylline-induced relaxation (pD2 = 4:12 ±0:06) was potentiated around 4-fold (pD2 = 4:80 ±0:44) in the presence of FGAL. Moreover, forskolininduced relaxation (pD2 = 6:51 ±0:06) was potentiated around 2.5-fold (pD2 = 6:90 ±0:05) by FGAL. Conversely, sodium nitroprusside-induced relaxation was unaffected, indicating that the AC/cAMP/PKA pathway, but not the NO pathway, may be modulated by the flavonoid. These results suggest that, in guinea-pig trachea, FGAL induces relaxation by pseudo-irreversible noncompetitive antagonism on muscarinic receptors, modulation of K+ and Ca2+ channels, as well as activation of the AC/cAMP/PKA pathway.

Spasmolytic effect of galetin 3,6-dimethyl ether, a flavonoid obtained from Piptadenia stipulacea (Benth) Ducke.

Piptadenia stipulacea (Benth) Ducke is a tree of the Caatinga, in Northeast Brazil, popularly known as "Jurema-branca", "Jurema malícia-da-serra", "Carcará" and "Calumbi". In folk medicine, a decoction or tincture of its bark and leaves are used to treat wounds and as healing agents. Galetin 3,6-dimethyl ether (FGAL) is a flavonoid isolated from the aerial components of Piptadenia stipulacea (Benth) Ducke. We decided to investigate a possible FGAL spasmolytic effect on preparations of both the guinea pig ileum and trachea, the rat uterus and the male rat aorta. FGAL inhibited oxytocin (IC(50) = 2.2 ± 0.4 × 10(-5) M) and carbachol (CCh)-induced (IC(50) = 7.7 ± 1.3 × 10(-5) M) phasic contractions in the rat uterus, but was more effective in the inhibition of the oxytocin-induced contractions. In the guinea pig ileum, FGAL equipotently inhibited CCh (IC(50) = 2.8 ± 0.4 × 10(-5) M) and histamine-induced (IC(50) = 2.3 ± 0.5 × 10(-5) M) phasic contractions. FGAL equipotently and concentration-dependently relaxed guinea pig trachea preparations pre-contracted with CCh, both in the absence (EC(50) = 0.8 ± 0.1 × 10(-5) M) and presence (EC(50) = 1.0 ± 0.1 × 10(-5) M) of a functional epithelium. FGAL also relaxed preparations of the rat aorta pre-contracted with phenylephrine in both the absence (EC(50) = 5.0 ± 1.1 × 10(-6) M) and presence (EC(50) = 5.4 ± 1.2 × 10(-6) M) of a functional endothelium. FGAL shows a non-selective spasmolytic effect on each of the smooth muscle preparations we have tested, but with a greater effect on those from the rat aorta. The relaxant effect on preparations of both the guinea pig trachea and the rat aorta seems to not involve the epithelium or endothelium-derived relaxing factors.

Aqueous and Methanolic Extracts of Caulerpa mexicana Suppress Cell Migration and Ear Edema Induced by Inflammatory Agents.

The regulation of the inflammatory response is essential to maintaining homeostasis. Several studies have investigated new drugs that may contribute to avoiding or minimizing excessive inflammatory process. The aim of this study was to evaluate the effect of extracts of green algae Caulerpa mexicana on models inflammation. In mice, the inflammatory peritonitis model is induced by zymosan. Previous treatment of mice with aqueous and methanolic extracts of C. mexicana was able to suppress the cell migration to the peritoneal cavity, in a time-dependent but not in a dose-dependent manner. The treatment of mice with C. mexicana extracts also decreased the xylene-induced ear edema, exerting strong inhibitory leukocyte migration elicited by zymosan into the air pouch. We concluded that administration of the extracts resulted in a reduction of cell migration to different sites as well as a decrease in edema formation induced by chemical irritants. This study demonstrates for the first time the anti-inflammatory effect of aqueous and methanolic extracts from the green marine algae Caulerpa mexicana.

The antinociceptive and anti-inflammatory activities of Piptadenia stipulacea Benth. (Fabaceae).

AIM: In this study, we attempted to identify the possible antinociceptive and anti-inflammatory actions of the aqueous phase, the ethyl acetate phase and one unknown flavonoid obtained from aerial parts of Piptadenia stipulacea, known in Brazil as "jurema-branca", "carcará" and "rasga-beiço". MATERIALS AND METHODS: Aerial parts of Piptadenia stipulacea were used and after fractionation, the flavonoid FGAL was obtained. Experiments were conducted on Swiss mice using the acetic acid-induced writhing test, the hot plate test, the formalin-induced pain test and zymosan A-induced peritonitis test. RESULTS: The aqueous and ethyl acetate phases (p.o., 100mg/kg); and the flavonoid FGAL (p.o. and i.p. at 100 micromol/kg), reduced the nociception produced by acetic acid, by 49.92%, 54.62%, 38.97% and 64.79%, respectively. In vivo inhibition of nociception by the ethyl acetate phase (100mg/kg, p.o.) in the hot plate test was favorable, indicating that this fraction exhibited central activity. The ethyl acetate phase (100mg/kg, p.o.) reduced the formalin effects in both phases by 28.51% and 55.72%, respectively. Treatment with the aqueous phase (100mg/kg, p.o.) and FGAL (100 micromol/kg, i.p.) only protected the second phase by 69.76% and 68.78%, respectively. In addition, it was observed in the zymosan A-induced peritonitis test that the aqueous phase, the ethyl acetate phase and the FGAL exhibited anti-inflammatory activity, reducing significantly the number of recruit cells by 35.84%, 37.70% and FGAL (1), respectively. CONCLUSIONS: These data demonstrate that the FGAL elicits pronounced antinociceptive activity against several pain models. The actions of this flavonoid probably are due to antioxidative properties. However, pharmacological and chemical studies are continuing in order to characterize the mechanism(s) responsible for this antinociceptive action and also to identify other active substances present in Piptadenia stipulacea.

The antinociceptive and anti-inflammatory activities of caulerpin, a bisindole alkaloid isolated from seaweeds of the genus Caulerpa.

The antinociceptive and anti-inflammatory activity of caulerpin was investigated. This bisindole alkaloid was isolated from the lipoid extract of Caulerpa racemosa and its structure was identified by spectroscopic methods, including IR and NMR techniques. The pharmacological assays used were the writhing and the hot plate tests, the formalin-induced pain, the capsaicin-induced ear edema and the carrageenan-induced peritonitis. Caulerpin was given orally at a concentration of 100 micromol/kg. In the abdominal constriction test caulerpin showed reduction in the acetic acid-induced nociception at 0.0945 micromol (0.0103-1.0984) and for dypirone it was 0.0426 micromol (0.0092-0.1972). In the hot plate test in vivo the inhibition of nociception by caulerpin (100 micromol/kg, p.o.) was also favorable. This result suggests that this compound exhibits a central activity, without changing the motor activity (seen in the rotarod test). Caulerpin (100 micromol/kg, p.o.) reduced the formalin effects in both phases by 35.4% and 45.6%, respectively. The possible anti-inflammatory activity observed in the second phase in the formalin test of caulerpin (100 micromol/kg, p.o.) was confirmed on the capsaicin-induced ear edema model, where an inhibition of 55.8% was presented. Indeed, it was also observed in the carrageenan-induced peritonitis that caulerpin (100 micromol/kg, p.o.) exhibited anti-inflammatory activity, reducing significantly the number of recruit cells by 48.3%. Pharmacological studies are continuing in order to characterize the mechanism(s) responsible for the antinociceptive and anti-inflammatory actions and also to identify other active principles present in Caulerpa racemosa.