Involvement of the L-arginine-nitric oxide pathway in the antinociception caused by fruits of Prosopis strombulifera (Lam.) Benth

Ethnopharmacological relevance

Prosopis strombulifera (Lam.) Benth. is a rhizomatous shrub that grows in the north and central zone of Argentina. In folk medicine, the fruits of this plant have been used as an astringent, anti-inflammatory and odontalgic agent and anti-diarrheic.

Aim of the study

To investigate the antinociceptive effect of ethanol (EE), chloroform (CE) and ethyl acetate (EtOAcE) extracts of Prosopis strombulifera fruits and the involvement of the l-arginine-nitric oxide pathway in this effect.

Materials and methods

The antinociceptive effects of the EE, CE and EtOAcE of Prosopis strombulifera fruits were evaluated in vivo using the formalin-induced pain test in mice with aspirin and morphine as reference antinociceptive compounds. The participation of the l-arginine-nitric oxide pathway in the antinociceptive effect was investigated in the same animal model using l-arginine as a nitric oxide (NO) precursor. The in vitro inhibitory effect of the extracts on LPS-induced nitric oxide production and iNOS expression was investigated in a J774A.1 macrophage-derived cell line.

Results

CE (300 mg/kg), in contrast to EE and EtOAcE, caused significant inhibition (p < 0.05) of the in vivo nociceptive response. Moreover, CE (100–1000 mg/kg, p.o.) produced a dose-dependent inhibition of the neurogenic and the inflammatory phases of the formalin test with inhibition values (at 600 mg/kg) of 42 ± 7% and 62 ± 7%, respectively. CE inhibition was more potent in the inflammatory phase, with an ID₅₀ of 400.1 (252.2–634.8) mg/kg. The antinociception caused by CE (600 mg/kg, p.o.) was significantly attenuated (p < 0.05) by i.p. treatment of mice with l-arginine (600 mg/kg). In addition, CE (100 μg/mL) produced significant in vitro inhibition (p < 0.001) of LPS-induced NO production, which was not observed with EE and EtOAcE at the same concentration. The inhibition of NO production by CE (10–100 μg/mL) was dose-dependent, with an IC₅₀ of 39.8 (34.4–46.1) μg/mL, and CE significantly inhibited LPS-induced iNOS expression in J774A.1 cells.

Conclusions

This study supports, in part, the ethnomedical use of Prosopis strombulifera fruits by showing that its CE produces moderate antinociception in vivo. The findings also provide scientific information for understanding the molecular mechanism involved in the analgesic effect of this plant.     

Antinociceptive activity of aqueous extract and isolated compounds of Lithrea molleoides

Ethnopharmacological relevance

Lithrea molleoides (Vell.) Engl. (Anacardiaceae) is a medicinal plant commonly used in traditional medicine in South America.

Aim of the study

In the present study, the in vivo antinociceptive effect of L. molleoides' aqueous extract and its isolated compounds has been investigated.

Materials and Methods

Antinociceptive activity was evaluated through writhing, formalin and hot plate tests in mice. The phytochemical analysis was performed.

Results

The extract produced significant inhibition on nociception induced by acetic acid (ED50: 8.7 mg/kg, i.p.) and formalin (ED50: 7.7 mg/kg, i.p.) administered intraperitoneally and also orally. Yohimbine diminished the activity of the extract in the acetic acid test meanwhile haloperidol enhanced its effect. Two majority compounds, shikimic and vanillic acid were active in chemical nociceptive models used in this work, producing the highest inhibition of the writhing response at a dose of 30 mg/kg i.p. (55.4% and 57.1%, respectively) meanwhile at 100 mg/kg p.o. produced a slight response (23.3% and 23.9%, respectively).

Conclusions

These results suggest that L. molleoides' aqueous extract produced antinociception possibly related to the presence of shikimic and vanillic acid. The adrenergic and dopaminergic systems seem to be involved in the mechanism of antinociception of the extract.     

Evaluation of the antinociceptive, anti-inflammatory and gastric antiulcer activities of the essential oil from Piper aleyreanum C.DC in rodents

Ethnopharmacological relevance

Piper aleyreanum is a small tree that is widely distributed in tropical and subtropical regions, mostly in North and South America, and is used as an immunomodulator, analgesic and antidepressant in folk medicine.

Aim of the study

This study was designed to investigate the antinociceptive, anti-inflammatory and gastric antiulcer activities of the essential oils from the aerial parts of Piper aleyreanum (EOPa) in rodents.

Materials and methods

The antinociceptive and anti-inflammatory effects of orally administered EOPa were evaluated in mice subjected to the formalin and pleurisy models, respectively. We also pretreated the rats with EOPa before acute ethanol-induced gastric lesions and measured gastric lesion extension and mucus and glutathione (GSH) levels in the gastric mucosa. Finally, we performed a phytochemical analysis of EOPa.

Results

The chemical composition of EOPa was analyzed by gas chromatography and mass spectrometry (GC/MS), which identified 35 compounds, representing 81.7% of total oil compounds. Caryophyllene oxide (11.5%), β-pinene (9%), spathulenol (6.7%), camphene (5.2%), β-elemene (4.7%), myrtenal (4.2%), verbenone (3.3%) and pinocarvone (3.1%) were the major oil constituents. The oral administration of EOPa (10–1000 mg/kg) significantly inhibited the neurogenic and inflammatory phases of formalin-induced licking, with ID50 values of 281.2 and 70.5 mg/kg, respectively. The antinociception caused by EOPa (100 mg/kg, p.o.) was not reversed by naloxone (1 or 5 mg/kg, i.p.) in the formalin test. EOPa (100–300 mg/kg, p.o.) did not affect animal motor coordination in an open-field model. In carrageenan-induced pleurisy, EOPa (1–100 mg/kg, p.o.) significantly decreased the total cell count, neutrophils and mononuclear cells with mean ID50 values of 53.6, 21.7 and 43.5 mg/kg, respectively. In addition, EOPa (1–30 mg/kg, p.o.) protected the rats against ethanol-induced gastric lesions with an ID50 value of 1.7 mg/kg and increased the mucus and GSH levels of the gastric mucosa to levels similar to those of the non-lesioned group.

Conclusions

These data show for the first time that EOPa has significant antinociceptive and anti-inflammatory actions, which do not appear to be related to the opioid system. EOPa also has interesting gastroprotective effects related to the maintenance of protective factors, such as mucus production and GSH. These results support the widespread use of Piper aleyreanum in popular medicine and demonstrate that this plant has therapeutic potential for the development of phytomedicines with antinociceptive, anti-inflammatory and gastroprotective properties.     

Antinociceptive activity of Mirabilis jalapa in mice

Ethnopharmacological relevance

The infusion or decoction of Mirabilis jalapa leaves is used in traditional medicine in Brazil to treat inflammatory and painful diseases.

Aim of the study

The present study examined the antinociceptive effect of Mirabilis jalapa extracts from leaves and stems in models of pain in mice.

Materials, methods and results

The crude hydroethanolic extract from leaves (CrdL) was more potent than the crude extract from stems (CrdS) to inhibit abdominal constrictions induced by acetic acid, with ID₅₀ values of 5.5 (2.3–13.1) and 18.0 (11.3–28.5) mg/kg, respectively. Among the fractions tested, the Eta fraction from leaves (Eta) was more effective (maximal inhibition of 83 ± 8%) and potent (ID₅₀ of 1.1 (0.6–2.1) mg/kg) to induce antinociception. Eta and CrdL also possessed an antinociceptive effect in the tail-flick test. Pre-treatment with naloxone did not modify the antinociceptive effect of Eta, but co-administration with atropine completely prevented it. This suggests that the antinociceptive effect might depend on the cholinergic system. Instead, Eta was not able to alter the acetylcholinesterase activity in blood or spinal cord. Concerning side effects, Eta did not alter locomotor activity, body temperature, gastrointestinal transit and did not produce gastric lesions.

Conclusion

Our results demonstrate that Mirabilis jalapa presents antinociceptive activity in mice, which supports its folkloric use as an analgesic.     

Acute toxicity, antinociceptive activity and indole alkaloids of aqueous extract from bark of Aspidosperma cuspa (Kunth) Blake

Etnopharmacological relevance

Aspidosperma cuspa (Kunth) Blake (Apocynaceae) is popularly known as “amargosa” or “cuspa”, and its bark is used in folk medicine primarily for pain.

Aim of the study

In the present study the acute toxicity, antinociceptive effect and alkaloids of the aqueous decoction extract of the Aspidosperma cuspa bark in mice was investigated.

Materials and methods

Acute toxicity was tested using a variation of the method described by Lichfield and Wilcoxon. The antinociceptive activity was evaluated using the acetic acid induced writhing and tail-flick tests. The phytochemical analysis was performed.

Results and conclusion

Oral administration of the extract did not cause animal death (LD₅₀>4 g/kg), and the histological analysis showed an absence of alterations in all organs examined. TD₅₀ of the extract was 0.5521 g/kg for male mice and 1.1565 g/kg for females. The aqueous extract at doses 276 mg/kg (p.o.) did not produce a significant inhibition of acetic acid-induced writhes, but showed a significant effect in tail-flick test. Naloxone, an opioid receptor antagonist, pretreatment inhibited significantly the antinociceptive activity of the extract. It is suggested that the aqueous decoction extract of the bark of Aspidosperma cuspa has an antinociceptive effect, and this may be mediated by opioid receptors. Three indole alkaloids (aspidocarpine, 11-methoxytubotaiwine and picraline) were isolated from the aqueous extract. The antinociceptive activity of the extract is presumed to be due to these compounds.     

Effect of Tulbaghia violacea on the blood pressure and heart rate in male spontaneously hypertensive Wistar rats

Ethnopharmacological relevance

Tulbaghia violacea Harv. (Alliaceae) is a small bulbous herb which belongs to the family Alliaceae, most commonly associated with onions and garlic. In South Africa, this herb has been traditionally used in the treatment of various ailments, including fever, colds, asthma, paralysis, hypertension and stomach problems. The aim of this study was to evaluate the effect of methanol leaf extracts (MLE) of Tulbaghia violacea on the blood pressure (BP) and heart rate (HR) in anaesthetized male spontaneously hypertensive rats; and to find out the mechanism(s) by which it acts.

Materials and methods

The MLE of Tulbaghia violacea (5–150 mg/kg), angiotensin I human acetate salt hydrate (ang I, 3.1–100 μg/kg), angiotensin II human (ang II, 3.1–50 μg/kg), phenylephrine hydrochloride (phenylephrine, 0.01–0.16 mg/kg) and dobutamine hydrochloride (dobutamine, 0.2–10.0 μg/kg) were infused intravenously, while the BP and HR were measured via a pressure transducer connecting the femoral artery and the Powerlab.

Results

Tulbaghia violacea significantly (p < 0.01) reduced the systolic, diastolic, and mean arterial BP; and HR dose-dependently. Ang I, ang II, phenylephrine and dobutamine all increased the BP dose-dependently. The hypertensive effect of ang I and the HR-increasing effect of dobutamine were significantly (p < 0.01) decreased by their co-infusion with Tulbaghia violacea (60 mg/kg). However, the co-infusion of ang II or phenylephrine with Tulbaghia violacea (60 mg/kg) did not produce any significant change in BP or HR when compared to the infusion of either agent alone in the same animal.

Conclusions

Tulbaghia violacea reduced BP and HR in the SHR. The reduction in BP may be due to actions of the MLE on the ang I converting enzyme (ACE) and β₁ adrenoceptors.     

Gut and airways relaxant effects of Carum roxburghianum

Ethnopharmacological relevance

Carum roxburghianum is traditionally used in hyperactive gastrointestinal and respiratory disorders. The present study was carried out to investigate the possible gut and airways relaxant potential of Carum roxburghianum to rationalize its folk uses.

Materials and methods

Crude extract of Carum roxburghianum (Cr.Cr) was studied in in vivo and in vitro techniques.

Results

Cr.Cr exhibited protective effect against castor oil-induced diarrhea in mice at 100–1000 mg/kg. In rabbit jejunum preparations, Cr.Cr (0.03–3.0 mg/mL) caused relaxation of spontaneous and K⁺ (80 mM)-induced contractions at similar concentrations, like papaverine. Pretreatment of tissues with Cr.Cr (0.1–1.0 mg/mL) shifted Ca⁺⁺ concentration–response curves (CRCs) to right, like verapamil. Cr.Cr (0.03 and 0.1 mg/mL) caused leftward shift of isoprenaline-induced inhibitory CRCs, similar to papaverine. In isolated guinea-pig ileum, Cr.Cr (0.01 and 0.03 mg/mL) produced rightward parallel shift of acetylcholine-curves, like atropine. Cr.Cr (1.0–30 mg/kg) caused suppression of carbachol (CCh, 100 μg/kg)-induced increase in inspiratory pressure of anaesthetized rats. In guinea-pig trachea, Cr.Cr (0.03–1.0 mg/mL) relaxed CCh and high K⁺-induced contractions, shifted isoprenaline-induced inhibitory CRCs to left at 0.1 and 0.3 mg/mL and CCh-curves parallel to right (0.01 and 0.03 mg/mL). Cr.Cr did not cause any mortality of mice up to 10 g/kg dose.

Conclusion

These results indicate that Carum roxburghianum possess combination of antidiarrheal, antispasmodic and bronchodilatory effects, which provides pharmacological basis to its traditional use in the disorders of gut and airways hyperactivity, like diarrhea, colic and asthma.     

Analgesic and anti-inflammatory effects of Ligularia fischeri leaves in experimental animals

Aim of the study

The ethanol extract (LF) of Ligularia fischeri var. spiciformis (leaf) has been evaluated for antinociceptive and anti-inflammatory activities in mice.

Materials and Methods

Analgesic and anti-inflammatory activities were studied by measuring nociception induced by formalin, acetic acid and hot-plate, and inflammation induced by carrageenan, formalin, and arachidonic acid.

Results

The acute treatment of mice with LF at doses of 100 and 200 mg/kg, by oral administration, produced a significant antinociceptive effect in the acetic acid-induced writhing, formalin-induced pain licking and hot-plate-induced pain. Also, the LF significantly inhibited both carrageenan- and formalin-induced inflammation as well as arachidonic acid-induced ear edema in mice.

Conclusions

These inhibitions were statistically significant (P < 0.05). Thus, our investigation suggests a potential benefit of Ligularia fischeri in treating conditions associated with inflammatory pain.     

Anti-inflammatory effect of triterpene 3β, 6β, 16β-trihydroxylup-20(29)-ene obtained from Combretum leprosum Mart & Eich in mice

Ethnopharmacological relevance

The 3β, 6β, 16β-trihydroxylup-20(29)-ene (TTHL) is a pentacyclic triterpene obtained from a medicinal plant named Combretum leprosum. In folk medicine, this plant is used to treat several diseases associated with inflammation and pain. We previously demonstrated that TTHL presents a significant antinociceptive effect, suggesting the involvement of the glutamatergic system.

Aim of the study

This study was designed to investigate the effect of TTHL on nociception and vascular permeability induced by acetic acid. We also evaluated the effect of TTHL on carrageenan-induced peritonitis and the levels of cytokines (interleukin 1-β [IL-1β], tumor necrosis factor α [TNF-α] and interleukin 10 [IL-10]) on peritoneal fluid.

Materials and methods

TTHL was administered orally by intra-gastric gavage (i.g.) 60 min prior to experimentation. Abdominal contractions and vascular permeability were induced by an intraperitoneal (i.p.) injection of acetic acid (0.6%). We also investigated whether TTHL decreases carrageenan-induced peritonitis (750 μg/cavity) by measuring leukocyte migration and vascular permeability. In addition, we evaluated the effects of TTHL on TNF-α, IL-1β and IL-10 release induced by carrageenan on peritoneal fluid. The levels of these cytokines were measured by ELISA.

Results

TTHL (0.01–10 mg/kg) administered by intra-gastric (i.g.) gavage inhibited (69±3%) acetic acid-induced abdominal constrictions, with an ID₅₀ of 0.15 (0.03–0.8) mg/kg. TTHL (10 mg/kg) also reduced the leukocyte infiltration induced by acetic acid, with an inhibition of 59±9 but had no effect on abdominal vascular permeability. In addition, indomethacin (10 mg/kg, i.p.) reduced the nociceptive behavior (92±1%), total leukocyte migration (29±3%) and capillary permeability (71±3%) induced by acetic acid. While the glucocorticoid dexamethasone (2 mg/kg, s.c.) reduced partially but significantly the nociception (31±1%), besides to promote a marked reduction on total leukocyte migration (60±2%) to the peritoneal cavity caused by acetic acid. In a model of peritonitis induced by carrageenan, TTHL also reduced total leukocyte migration, mainly neutrophils (inhibition of 84±3% and 85±2% at 30 mg/kg and 100 mg/kg, respectively). Likewise, dexamethasone (0.5 mg/kg, i.p.) resulted in an inhibition of 93±3%. Nevertheless, carrageenan-induced abdominal vascular permeability was reduced by dexamethasone but was not altered by TTHL. Furthermore, dexamethasone and TTHL significantly reduced the TNF-α and IL-1β levels in peritoneal fluid, whereas the IL-10 levels were unchanged.

Conclusions

Altogether, our data confirm the antinociceptive effect of TTHL and demonstrate its effect in inflammatory animal models, providing novel data about this compound, which could be useful as an anti-inflammatory drug.     

Antiulcer principle from Zingiber montanum

Ethnopharmacological relevance

Rhizome of Zingiber montanum has been extensively used as a folk medicine to ameliorate peptic ulcer at northern part of Bangladesh.

Aim of the study

To identify the antiulcer principle of the MeOH extract of the rhizome of Zingiber montanum by an ex vivo bioassay guided chromatographic separation and purification, and structure elucidation of the purified compound by spectroscopic methods.

Materials and methods

Dried powder of Zingiber montanum rhizomes was extracted with MeOH. The antiulcer activity of the crude extract and its chromatographic fractions were evaluated by the inhibition of 1 N HCl induced gastric lesions in Swiss albino mice. The pure compound was purified from the active fraction by crystallization with hexanes. Structure of the pure compound was elucidated by spectroscopic methods. The antiulcer activity of the pure compound was evaluated by the inhibition of 1 N HCl, 95% ethanol and indomethacin induced gastric lesions in mice.

Results

The MeOH extract of Zingiber montanum showed 61.97% and 83.10% inhibition of the 1 N HCl induced gastric lesions at doses of 200 mg/kg and 400 mg/kg, respectively, in mice. Chromatographic separation on silica gel of the extract was yielded seven fractions and the fraction 2 was found to have most potent antiulcer activity in mice. This fraction showed 77.46% inhibition of the 1 N HCl induced gastric lesions at a dose of 40 mg/kg in mice. Crystallization of the fraction yielded 1 (zerumbone, 180 mg). It showed statistically 45.77% and 92.25% inhibition of 1 N HCl induced gastric lesions in mice at doses of 20 mg/kg and 40 mg/kg, respectively. It also showed 29.07% and 45.35% inhibition of 95% ethanol induced gastric mucosal damage, and 64.76% and 72.38% inhibition of indomethacin induced gastric lesions in mice at doses of 20 mg/kg and 40 mg/kg, respectively.

Conclusion

Zerumbone (1) showed potent cytoprotective effect against necrotizing agent (HCl) and non-steroidal anti-inflammatory drug (indomethacin) induced gastric ulceration. It also exhibited moderate cytoprotective effect against noxious agent (EtOH) induced gastric lesions. It can be considered as a promising new antiulcer natural drug lead.     

Evaluation of diuretic activity of Amaranthus spinosus Linn. aqueous extract in Wistar rats

Ethnopharmacological relevance

Traditional Siddha medicine literature claims that the Amaranthus spinosus Linn. (family: Amaranthaceae) whole plant possesses diuretic property.

Aim of the study

To evaluate the diuretic potential of Amaranthus spinosus aqueous extract (ASAE) in rats.

Material and methods

Different concentrations of ASAE (200, 500, 1000, 1500 mg/kg), thiazide (10 mg/kg) and vehicle were orally administered to rats (n = 6 animals per group) and their urine output was collected after 24 h. Volume, pH, Na⁺, K⁺ and Cl⁻ concentrations of urine were estimated.

Results

ASAE produced increase in Na⁺, K⁺, Cl⁻ excretion, caused alkalinization of urine, showed strong saluretic activity and carbonic anhydrase inhibition activity. These effects were observed predominantly at 500 mg/kg dose and there was no dose–response relationship.

Conclusion

Our study strongly suggests that the Amaranthus spinosus is acting as a thiazide like diuretic with carbonic anhydrase inhibitory activity which restates the claim as diuretic herb in Siddha medicine.     

Involvement of 5-HT1A in the anxiolytic-like effect of dichloromethane fraction of Pimenta pseudocaryophyllus

Ethnopharmacological relevance

Medicinal applications of Pimenta pseudocaryophyllus infusion as a diuretic and aphrodisiac agent as well as tranquilizer in the form of tea for the treatment of emotional tension in Brazilian folk medicine has been in practice since time immemorial. Despite its popular therapeutic acceptance and claims, there are scanty scientific reports to corroborate its central biological activities.

Aim

To characterize anxiolytic-like effect of the dichloromethane fraction (DF) obtained from ethanolic leaf extract of the Pimenta pseudocaryophyllus and identify mechanisms of action involved while seeking to support its popular use as a soothing agent.

Material and methods

Mice (25–35 g) were treated orally with DF obtained from ethanolic leaf extract of Pimenta pseudocaryophyllus and were submitted to light-dark box (LDB) and elevated plus maze (EPM) tests. Different groups of mice were treated with flumazenil and NAN-190 to identify mechanisms of action involved in the anxiolytic-like effect of DF.

Results

Treatment with DF increased number of transitions and time spent in the light compartment of the LDB while the time spent and numbers of entries in the open arm of the LCE were significantly increased. Pre-treatment of the animal with flumazenil (2 mg/kg, i.p. – competitive antagonist of benzodiazepine site of GABA_A receptor) did not block this effect, thereby excluding participation of benzodiazepine site of the GABA_A receptor. However, anxiolytic-like effect of DF was reversed by pre-treatment with NAN-190 (0.5 mg/kg, i.p. – an antagonist of the 5-HT_1A receptor) thereby suggesting involvement of 5-HT_1A receptor. The thin layer chromatography and high-performance liquid chromatography analysis indicated the predominance of (E)-methyl isoeugenol and oleanolic acid in DF.

Conclusion

These results support the popular use of Pimenta pseudocaryophyllus as a calming agent and suggest the involvement of 5-HT_1A receptor.     

Hancornia speciosa: indications of gastroprotective, healing and anti-Helicobacter pylori actions

Ethnopharmacological relevance

Mangaba (Hancornia speciosa Gomez) is a medicinal plant frequently cited in ethnopharmacological inventories of the central region of Brazil against gastrointestinal disorders such as diarrhoea, ulcer, gastritis and stomachache.

Aim of the study

The hydroalcoholic extract (HE) and infusion (BI) of Hancornia speciosa bark were investigated for their ability to prevent and heal rodent gastric ulcer.

Materials and methods

The preventive and healing action of both preparations of Hancornia speciosa were evaluated in experimental models in rodents that simulated this disease in human gastric mucosa.

Results

BI did not exert gastroprotective effect, in contrast to HE (500 mg/kg, p.o.) that decreased (p < 0.05) the severity of gastric damage induced by HCl/ethanol (52%), indomethacin/bethanechol (51%), stress (52%) or pylorus ligature experiments (54%). HE increased (p < 0.05) the pH and decreased acid output of gastric juice. This extract promoted increase of mucus amount (3.62 mg/wt. tissue vs. 5.81 mg/wt. tissue), healing action (67%) and displayed anti-Helicobacter pylori effect.

Conclusions

The antiulcer action of Hancornia speciosa resulted in increase of gastric mucus formation and antioxidant properties of polymeric proanthocyanidins present in the bark composition of this medicinal plant.     

Beneficial effects of the ethanol extract of Caesalpinia pyramidalis on the inflammatory response and abdominal hyperalgesia in rats with acute pancreatitis

Ethnopharmacological relevance

Caesalpinia pyramidalis Tul. (Fabaceae) is a plant found in the Northeast of Brazil that is popularly used to treat inflammation. Acute pancreatitis (AP) is an inflammatory disease for which abdominal pain is a relevant symptom. As there is no specific therapy for AP, we investigated the effect of the ethanol extract from the inner bark of C. pyramidalis (EECp) on the AP induced by common bile duct obstruction (CBDO) in rats.

Material and methods

AP was induced in male Wistar rats (200–250g, n=6–8) through laparotomy and subsequent CBDO. Animals were euthanized after 6 (G6h) or 24 h (G24h) of induction. In the G6h protocol, animals were pretreated with EECp (100–400 mg/kg, p.o.) or vehicle (Tween 80; 0.2%) 1 h before CBDO or sham surgery. For the G24h protocol, rats were pretreated with EECp (400 mg/kg, 1 h before CBDO or 1 h before and 12 h after CBDO) or vehicle. The following parameters were measured: inflammatory/oxidative (myeloperoxidase activity and malondialdehyde formation in the pancreas and lung, leukocyte counts in the blood and serum nitrate/nitrite), enzymatic (serum amylase and lipase levels) and nociceptive (abdominal hyperalgesia).

Results

Induction of AP by CBDO significantly increased all the parameters evaluated in both G6h and G24h protocols when compared with the respective sham group. In the G6h protocol, the EECp pretreatment (400 mg/kg) significantly reduced all these parameters, besides completely inhibiting abdominal hyperalgesia. The same profile of reduction was observed from two administrations of EECp in the G24h protocol, while one single dose of EECp was able to significantly reduce pancreatic MDA, serum lipase levels, leukocyte counts in the blood and abdominal hyperalgesia without affecting the other parameters in the G24h protocol. Furthermore, rutin was found in the EECp.

Conclusions

Our results demonstrated that EECp decreases inflammation, lipoperoxidation and hyperalgesia in CBDO-induced AP, making it of interest in future approaches to treat this condition.     

Evidence for a role of 5-HT1A receptor on antinociceptive action from Geissospermum vellosii

Ethnopharmacological relevance

Geissospermum vellosii is a tree widely found throughout the Amazonic forest and frequently used by the native population for painful disorders.

Aim of the study

The present study examined the antinociceptive effects of Geissospermum vellosii in behavioral models of nociception.

Materials, methods and results

Oral administration of crude extract of Geissospermum vellosii or its dichloromethane fraction (1–100 mg/kg) inhibited formalin-induced inflammatory nociception and acetic acid-induced visceral nociception. The antinociceptive effect of Geissospermum vellosii was unrelated with motor dysfunctions. Furthermore, the alkaloid 12-metoxy-1-methyl-aspidospermidine (0.001–1 mg/kg), isolated from the dichloromethane fraction, also produced antinociception. The antinociception caused by the dichloromethane fraction was significantly attenuated by pre-treatment of mice with p-chlorophenylalanine methyl ester (PCPA, an inhibitor of serotonin synthesis, 100 mg/kg once a day for 4 consecutive days) and WAY-100635 (a 5-HT_1A receptor antagonist, 0.3 mg/kg). In contrast, dichloromethane fraction antinociception was not affected by pre-treatment of animals with ketanserin (a 5-HT₂ receptor antagonist, 0.3 mg/kg) or ondansetron (a 5-HT₃ receptor antagonist, 0.5 mg/kg).

Conclusions

Together, these results indicate that Geissospermum vellosii produces antinociception through an interaction with 5-HT_1A receptors. Furthermore, the alkaloid 12-metoxy-1-methyl-aspidospermidine contributes to the antinociceptive properties reported for Geissospermum vellosii.     

Effect on blood pressure of a dietary supplement containing traditional medicinal plants of Côte d'Ivoire

Ethnopharmacological relevance

A medicinal composition containing salt (sodium chloride) is given as a traditional dietary supplement to hypertensive patients (TDSHP) in Côte d’Ivoire. It consists of whole plant of Bidens pilosa (Asteraceae) and fresh leaves of Moringa oleifera (Moringaceae).

Aim of the study

The aim of this study was to establish the scientific basis for the use of this traditional recipe rich in sodium chloride in hypertension settings.

Materials and methods

We used a total aqueous extract of this traditional dietary supplement containing medicinal plants (Bidens pilosa, Moringa oleifera) and salt (sodium chloride). Experiment was carried out to evaluate its effect on arterial blood pressure of rabbits. The experimental device used for recording blood pressure in rabbits is based on the principle of Ludwig mercury manometer.

Results

TDSHP between 5 × 10⁻⁸ and 5 × 10⁻² mg/kg caused a dose-dependent hypotension. TDSHP elicited drops in blood pressure ranging between 7.14 ± 4 and 100 ± 7.5%, compared to normal blood pressure of rabbits. Fifty percent effective dose of TDSHP was 3.95 × 10⁻⁴ mg/kg. Similarly as the hypotension induced by acetylcholine, the one caused by TDSHP at dose of 3.95 × 10⁻⁴ mg/kg in rabbit was progressively inhibited by atropine, dosed between 5 × 10⁻⁴ to 5 × 10⁻² mg/kg. The percentage drop of recorded blood pressure ranged from 50.3 ± 1.87 to 3.71 ± 1.09% compared to the normal value of blood pressure. In the presence of atropine, TDSHP effect was partially inhibited. The same increasing doses of TDSHP reduced significantly the increase of blood pressure induced by adrenaline dosed at 4.76 × 10⁻⁴ mg/kg from 89.3 ± 2.19 to 1.19 ± 0.59%.

Conclusion

The consumption of this traditional dietary supplement is justified in hypertensive patients according to its composition and its ability to reduce blood pressure has been demonstrated experimentally. TDSHP should not be considered as an antihypertensive drug, it remains to us a salt substitute to be taken with moderation with strict adherence to the traditional dose.     

Evaluation of the antinociceptive activity of extracts of Sonchus oleraceus L. in mice

Ethnopharmacological relevance

Sonchus oleraceus L. has been used to relieve pain in Brazilian folk medicine.

Aim of the study

Sonchus oleraceus L. has been used to relieve pain in Brazilian folk medicine. This study was conducted to establish the antinociceptive properties of hydroethanolic and dichloromethane extracts from aerial parts of Sonchus oleraceus in mice using chemical and thermal models of nociception.

Materials and methods

The formalin, hot plate, and tail immersion tests as well as acetic acid-induced writhing were used to investigate the antinociceptive activity in mice.

Results

Given orally, the extracts at test doses of 30–300 mg/kg, produced significant inhibitions on chemical nociception induced by intraperitoneal acetic acid and subplantar formalin since decreased the number of writhing episodes and the time licking. Treatment with the extracts in the same doses produced a significant increase of the reaction time in tail immersion and in the hot plate test. The extracts administered at 300 mg/kg, p.o. had a stronger antinociceptive effect than indomethacin (5 mg/kg, p.o.) and morphine (10 mg/kg, p.o.).

Conclusion

The extracts of Sonchus oleraceus markedly demonstrated antinociceptive action in mice, which supports previous claims of its traditional use.     

Central depressant activity of butanol fraction of Securinega virosa root bark in mice

Ethnopharmacological relevance

Securinega virosa is a commonly used medicinal plant in African traditional medicine in the management of epilepsy and mental illness. Previous studies in our laboratory showed that the crude methanol root bark extract of the plant possesses significant behavioral effect in laboratory animals. In an attempt to isolate and characterize the biological principles responsible for the observed activity, this study is aimed at evaluating the central depressant activity of the butanol fraction of the methanol root bark extract of Securinega virosa.

Materials and methods

The medial lethal dose of the butanol fraction was estimated using the method of Lorke. Preliminary phytochemical screening was conducted on the butanol fraction using standard protocol. The behavioral effect of the butanol fraction (75, 150 and 300 mg/kg) was evaluated using diazepam induced sleep test, hole-board test, beam walking assay, staircase test, open field test and elevated plus maze assay, all in mice.

Results

The median lethal dose of the butanol fraction was estimated to be 1256.9 mg/kg. The preliminary phytochemical screening revealed the presence of tannins, saponins, alkaloids, flavonoids, cardiac glycosides, similar to those found in the crude methanol extract. The butanol fraction significantly (P < 0.001) reduced the mean onset of sleep in mice and doubled the mean duration of sleep in mice at the dose of 75 mg/kg. The butanol fraction and diazepam (0.5 mg/kg) significantly (P < 0.01–0.001) reduced the number of head dips in the hole-board test suggesting sedative effect. The sedative effect of the butanol fraction was further corroborated by its significant (P < 0.01–0.001) reduction of the number of step climbed and rearing in the staircase test. The butanol fraction did not significantly increase the time taken to complete the task and number of foot slips in the beam walking assay, suggesting that it does not induce significant motor coordination deficit. Diazepam (2 mg/kg), the standard agent used significantly (P < 0.01) increased the number of foot slips. In the open field test, the butanol fraction significantly reduced the number of square crossed as well as the number of rearing. However, the butanol fraction did not significantly alter the behavior of mice in the elevated plus maze assay, while diazepam (0.5 mg/kg) significantly (P < 0.05) increased the time spent in the open arm and reduced the number of closed arm entry.

Conclusion

The findings of this study suggest that the butanol fraction of Securinega virosa root bark contains some bioactive principles that are sedative in nature.     

Pharmacological basis for the medicinal use of muskmelon base (Pedicellus Melo.) for abdominal distention and constipation

Ethnopharmacological relevance

Muskmelon base (Pedicellus Melo.) has a long history (Ming Dynasty) as a Chinese traditional medicine. According to traditional use, it was prepared as rectal suppositories for treating abdominal distention and constipation. The present study was carried out on the pharmacological basis for the medicinal use of muskmelon base.

Aim of the study

The objective of this study was to determine the pharmacological basis for the medicinal use of the ethanol extract from muskmelon base (EMB) for abdominal distention and constipation.

Materials and methods

In this study, we report the gastrointestinal prokinetic action of EMB following single rectal or large intestinal administration. Laxative activity, gastric emptying and small intestinal transit tests were examined in ICR mice. SD rats were used to determine changes in large intestinal transit and contractile effects of the proximal colon in vivo. Guinea pigs were used to evaluate the contractile effects of the proximal colon and the possible mechanism or mechanisms on proximal colon activity ex vivo. Moreover, the acute toxicity of EMB was evaluated.

Results

In the in vivo experiments, the acute toxicity test showed that the maximum tolerated dose (MTD) of EMB was 400 mg/kg. A laxative effect was observed in mice at different dosages (6.5, 13 and 26 mg/kg). EMB showed a dose-dependent acceleration of gastric emptying (13 and 26 mg/kg). It also promoted both small intestinal (6.5, 13 and 26 mg/kg) and large intestinal (4, 8 and 16 mg/kg) transit activity. In the SD rat model, single rectal administration of EMB (8 and 16 mg/kg) showed a significant increase in both the frequency and amplitude of proximal colon smooth muscle contractility. These increases in amplitude and frequency peaked 30–60 min after EMB administration and corresponded with the results of the laxative activity test. The ex vivo experiments showed that varying doses of EMB (11.5, 23 and 46 mg/kg) had a direct prokinetic effect that was sensitive to atropine.

Conclusions

Our results show that EMB is a low dosage, fast acting drug with a large therapeutic window (4–400 mg/kg) and shows significant gastrointestinal prokinetic action after single rectal or large intestinal administration. This gastrointestinal prokinetic effect was stronger in the intestines than in the stomach. This effect was sensitive to atropine, suggesting that EMB acts mainly through cholinergic mechanisms.     

Characterization of the antinociceptive and anti-inflammatory activities from Cocos nucifera L. (Palmae)

Aim of the study

Cocos nucifera cultivated in Brazil is known as “coco-da-Bahia” or “coqueiro-da-Índia”. The tea from the husk fiber is widely used to several inflammatory disorders. Crude extract and fractions obtained from Cocos nucifera “common variety” were evaluated to test the anti-inflammatory and antinociceptive activities.

Materials and methods

Crude extract (CE, 50, 100, and 150 mg/kg), fraction 1 (F1, molecular weight lesser than 1 kDa, 1, 10, and 50 mg/kg), fraction 2 (F2, molecular weight higher than 1 kDa, 1, 10, and 50 mg/kg), and the references drugs morphine (5 mg/kg), acetilsalicilic acid (200 mg/kg), prometazine (30 mg/kg), and metisergide (5 mg/kg) were evaluated on models of analgesia and inflammation.

Results

CE, F1, and F2 significantly develop peripheral and central antinociceptive activity but with less effect on supra-spinal regions of the brain. Administration of the opioid antagonist, naloxone (5 mg/kg) inhibited the antinociceptive effect indicating that Cocos nucifera crude extract and fractions may be acting in opioid receptors. CE and F1 also inhibited rat paw edema induced by histamine, and serotonin.

Conclusions

results demonstrated that Cocos nucifera and its fractions have antinociceptive and anti-inflammatory activities which confirm the popular use of this plant in several inflammatory disorders.