Antinociceptive activity of methanol extract of fruits of Capparis ovata in mice

Ethnopharmacological relevance

Capparis ovata Desf. and Capparis spinosa L. have wide natural distribution in Turkey and they are consumed in pickled form. Flower buds, root bark, and fruits of the plant are used in folk medicine due to their analgesic, wound healing, cell regeneration, tonic, and diuretic effects.

Aim of the study

In this study, we attempted to identify the possible antinociceptive action of methanol extract prepared from fruits of Capparis ovata.

Materials and methods

Using tail immersion, hot plate and writhing tests, the antinociceptive effect of the methanol extract of Capparis ovata (MEC) fruits was assessed after intraperitoneal administration into mice. Morphine sulfate (5 mg/kg; i.p.) and diclofenac (10 mg/kg; i.p.) were used as reference analgesic agents. Naloxone (5 mg/kg; i.p.) was also tested.

Results

MEC was studied at the doses of 50, 100, and 200 mg/kg (i.p.) and exhibited significant antinociceptive activities in all tests used. The above-mentioned doses of the extract reduced the writhing responses by 32.21, 55.70, and 68.36%, respectively. MPE% were increased by 7.27, 12.07, 14.60% in the tail immersion, and 7.88, 11.71, 16.73% in the hot plate test at the tested doses, respectively. Naloxone antagonized antinociceptive effect at the doses of 100 and 200 mg/kg whereas partially antagonized the effect of MEC at the dose of 50 mg/kg.

Conclusions

Based on the results obtained, it can be concluded that MEC has antinociceptive effects both at the peripheral and central levels.     

Antinociceptive activity of fractions from Couroupita guianensis Aubl. leaves

Ethnopharmacological relevance

Couroupitaguianensis Aubl. (Lecythidaceae) is popularly known in Brazil as “abricó-de-macaco”. Infusions or teas obtained from its leaves, flowers, and barks are used in South America for the treatment of several disorders such as pain and inflammatory processes.

Aim of the study

Evaluate antinociceptive effects of crude ethanol extract (CEE) and its fractions in three analgesic models (acetic acid-induced contortions, tail flick, and hot plate) and study the possible mechanism of their action.

Materials and methods

CEE, hexane, dichloromethane, ethyl acetate, and butanol fractions (10, 30, and 100 mg/kg, p.o.) and the reference drug morphine (5 mg/kg, s.c.) were evaluated. To elucidate the mechanism of action from the fractions, animals were pre-treated (30 min) with atropine (muscarinic receptor antagonist, 1 mg/kg, s.c.), mecamylamine (nicotinic receptor antagonist, 2 mg/kg, s.c.), naloxone (opioid receptor antagonist, 1 mg/kg, s.c.) or l-nitro arginine methyl ester (l-NAME, nitric oxide synthase inhibitor, 3 mg/kg, s.c.).

Results

CEE and fractions significantly inhibited the number of contortions induced by acetic acid. All fractions showed antinociceptive activity in the tail flick model, being the hexane and ethyl acetate the most potent and long acting fractions. In the hot plate method the highest effect observed was at the dose of 100 mg/kg from all fractions. Administration of naloxone inhibited the antinociceptive effect of fractions. Pre-treatment of mice with atropine reduced the antinociceptive activity of CEE and its fractions, the exception being the dichloromethane fraction. Mecamylamine did not inhibited the effect of dichloromethane fraction. l-NAME reduced the anti-hyperalgesic effect of all fractions, but the most prominent effect was observed in the antinociceptive activity caused by CEE and butanol fraction.

Conclusions

Results obtained demonstrated that Couroupita guianensis CEE and its fractions have antinociceptive activity that is mediated, at least in part, by opioid and cholinergic systems and nitric oxide pathway.     

Characterization of the antinociceptive and anti-inflammatory activities of fractions obtained from Copaifera multijuga Hayne

Ethnopharmacological relevance

Copaifera multijuga Hayne (Leguminosae) is a tree that produces an oleoresin, which is extensively commercialized in Brazil as capsules or crude oil for the treatment of several disorders. Ethnopharmacological studies show a diversity of indications such as anti-inflammatory and epidermal wound cicatrization.

Aim of the study

In the present work three fractions obtained from Copaifera multijuga oleoresin (hexane (HF), chloroform (CF), and methanol (MF) from a KOH impregnated silica gel column chromatography, representing the three main classes of compounds in the Copaifera genus (hydrocarbon sesquiterpenes, oxygenated sesquiterpenes and acidic diterpenes), were evaluated using antinociceptive and anti-inflammatory models.

Materials and methods

HF, CF, and MF (doses ranging between 1 and 150 mg/kg, depending on the model used), Copaifera multijuga oleoresin (CMO, 100 mg/kg, p.o.) and the reference drug morphine (5 mg/kg, p.o.) were evaluated using models for analgesia (acetic acid-induced contortions and tail flick) or inflammation (rat paw oedema and increase in vascular permeability). To elucidate the mechanism of action from the fractions, animals were pre-treated with naloxone (opioid receptor antagonist, 5 mg/kg, i.p.).

Results

Fractions significantly inhibited (in a concentration-dependant way) the number of contortions induced by acetic acid and the second phase of formalin-induced licking response. Similar results were observed in the tail flick model. The central antinociceptive effect for HF and CF at the doses of 50 and 100 mg/kg was higher than the one observed for morphine (1 mg/kg). Administration of naloxone inhibited the antinociceptive effect of fractions indicating that HF, CF, and MF may be acting on opioid receptors. All three fractions also inhibited rat paw oedema and the increase in vascular permeability induced by several phlogistic agents (carrageenan, histamine, and serotonin).

Conclusions

Our results indicate that fractions obtained from Copaifera multijuga Hayne demonstrate an antinociceptive effect probably mediated by opioid receptors, and anti-inflammatory activity through inhibition of histaminergic and serotoninergic pathways.     

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.     

Anti-inflammatory and antinociceptive effects of the stem bark of Byrsonima intermedia A. Juss

Ethnopharmacological relevance

Byrsonima intermedia A. Juss. is popularly known as “murici pequeno” and is native to the Brazilian Cerrado. This species has been used as an antimicrobial, anti-hemorrhagic, anti-diarrheal and anti-inflammatory. Nevertheless, scientific information regarding Byrsonima intermedia is limited; there are no reports related to its possible anti inflammatory and antinociceptive effects. This study employed in vivo inflammatory and nociceptive models to evaluate the scientific basis for the traditional use of Byrsonima intermedia.

Materials and methods

Carrageenan-induced paw edema, peritonitis and fibrovascular tissue growth induced by s.c. cotton pellet implantation tests were used to investigate the anti-inflammatory activity of Byrsonima intermedia aqueous extract (BiAE) in rats. Mechanical nociceptive paw, formalin and hot plate tests were used to evaluate the antinociceptive activity in mice. High-performance liquid chromatography (HPLC), phytochemistry screening and determination of total phenolics and flavonoids were used to determine the chemical profile of the BiAE.

Results

BiAE at test doses of 30-300 mg/kg p.o. clearly demonstrated anti-inflammatory effects by reduced carrageenan-induced paw edema, by inhibited leukocyte recruitment into the peritoneal cavity and, in the model of chronic inflammation, by using the cotton pellet-induced fibrovascular tissue growth in rats. The extracts at test doses of 30-300 mg/kg p.o. clearly demonstrated antinociceptive activity in all tests. Administration of the opioid receptor antagonist naloxone completely inhibited the antinociceptive effect induced by BiAE (100 mg/kg).

Conclusion

BiAE markedly exhibits anti-inflammatory action in rats and antinociceptive activity in mice. Thus, it may be useful in the treatment of inflammatory hyperalgesic disorders, which supports previous claims of its traditional use.     

Antinociceptive effects of ethanolic extract from the flowers of Acmella oleracea (L.) R.K. Jansen in mice

Ethnopharmacological relevance

In Brazil, Acmella oleracea (L.) R.K. Jansen, popularly known as “jambu”, has been used by some communities from Amazon region to treat toothache. In this study we examined the antinociceptive effect of the ethanolic extract obtained from the flowers of Acmella oleracea (EEAO) in animal models of nociceptive (chemical and thermal) and neuropathic (partial sciatic nerve ligation) pain.

Materials and methods

Adult male mice were treated by intraperitoneal route (i.p.) with EEAO before the induction of nociceptive response by formalin, capsaicin and cinnamaldehyde, thermal heat hyperalgesia (hot plate test) and mechanical allodynia (traumatic sciatic nerve injury). Acute toxicity and non-specific sedative effects were evaluated.

Results

EEAO (10, 30 and 100 mg/kg) reduced both neurogenic and inflammatory phases of the formalin- and also capsaicin- and cinnamaldehyde-induced orofacial nociception. Interestingly, EEAO at 100 mg/kg (i.p.) also reversed capsaicin-induced heat hyperalgesia assessed as the latency to paw withdrawal in the hot plate test. Also in the hot plate test, paw withdrawal latency was increased by EEAO (100 mg/kg) and this response was only partially reversed by naloxone. Furthermore, EEAO (100 mg/kg) also reduced mechanical allodynia caused by partial sciatic nerve ligation for 3 h. The estimated LD50 value was 889.14 mg/kg and EEAO did not alter the locomotion of animals in the open-field test.

Conclusion

Taken together, our data show that EEAO produces prevalent antinociceptive effects and does not cause adverse effects. The presence of N-alkylamides, including spilanthol, suggests that the therapeutic effect of EEAO is related to its highest anesthetic activity.     

Antinociceptive activity of ethanolic extract and isolated compounds of Urtica circularis

Ethnopharmacological relevance

Urtica circularis (Hicken) Sorarú is a medicinal plant commonly used in traditional medicine to relieve pain in inflammatory processes.

Aim of the study

In the present study, the in vivo antinociceptive effect of Urtica circularis ethanolic 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: 72.2 mg/kg, i.p.) and formalin (ED50: 15.8 mg/kg, i.p.) administered intraperitoneally and also orally. Atropine diminished the activity of the extract in the acetic acid test. In this model, at dose of 10 mg/kg i.p., vitexin was the most active of the isolated compounds (inhibition of 91%), and chlorogenic acid, caffeic acid and vicenin-2 (6,8-di-C-glucosyl apigenin) produced an inhibition of 72%, 41% and 41%, respectively, whereas apigenin did not show any activity.

Conclusions

These results suggest that Urtica circularis extract produced antinociception possibly related to the presence of vitexin, chlorogenic, caffeic acid and vicenin-2. The activation of cholinergic systems seems to be involved in the mechanism of antinociception of the extract.     

The latex obtained from Hancornia speciosa Gomes possesses anti-inflammatory activity

Aim of the study

Hancornia speciosa Gomes (Apocynaceae) is a tree that is widely distributed throughout Brazil. Its latex is collected and used extensively to treat acne, warts, diseases related to bursitis, and inflammation. In this work, we describe the anti-inflammatory effects of the latex.

Materials and methods

The latex from Hancornia speciosa (0.06-1.3 mg/kg, p.o.) and the reference drug acetylsalicylic acid (ASA, 200 mg/kg, p.o.) were evaluated in analgesia (formalin-induced licking, acetic acid-induced contortions, and hot plate) and inflammation models (formalin-induced licking, paw oedema, and subcutaneous air pouch, with measurement of cell migration, exudate volume, protein extravasations, nitric oxide, prostaglandin E2, TNF-α, and IL-6, and expression of the enzymes inducible nitric oxide synthase and cyclooxygenase 2).

Results

The latex from Hancornia speciosa significantly inhibited the number of writhings and the time that the animal spent licking the formalin-injected paw (second phase). Doses of 0.1-1.3 mg/kg latex reduced carrageenan-induced rat paw oedema. However, only the highest doses (0.6 and/or 1.3 mg/kg) reduced the oedema induced by bradykinin, histamine, and serotonin. The latex also inhibited inflammation induced by subcutaneous carrageenan injection, cell migration, exudate volume, protein extravasations, increased levels of inflammatory mediators (nitric oxide, prostaglandin E2, TNF-α, and IL-6) produced in the pouch, and increased expression of the enzymes nitric oxide synthase and cyclooxygenase 2.

Conclusions

Our results indicate that the latex obtained from Hancornia speciosa demonstrates significant anti-inflammatory activity through the inhibition of nitric oxide, PGE2, and cytokine production, thus confirming the popular use of this plant as an anti-inflammatory agent.     

Orofacial antinociceptive effect and antioxidant properties of the hydroethanol extract of Hyptis fruticosa salmz ex Benth

Ethnopharmacological relevance

Hyptis fruticosa is a plant native to Brazil with antinociceptive and antiinflamatory properties. This study evaluated the antinociceptive activity of the hydroethanol extract of the plant leaves (CHEE) against orofacial pain as well as its in vitro effect against lipid peroxidation.

Materials and methods

The antinociceptive activity was investigated in mice orally treated with different doses of the CHEE (50, 100, and 200 mg/kg) and morphine (5 mg/kg) using formalin, glutamate, and capsaicin orofacial pain models using. Lipoperoxidation was induced in egg yolk by AAPH and FeSO₄ in the absence and presence of the CHEE (5, 50, 100, and 150 μg/mL).

Results

CHEE (200 mg/kg) significantly reduced (ρ<0.001) the pain response in the first (69.6%) and second (81.8%) phases of the formalin test, while the nociception caused by capsaicin was significantly (ρ<0.001) reduced by up to 62% at 200 mg/kg of extract. When glutamate was used as algogen, a significant (ρ<0.001) nociception reduction of up to 85% at 200 mg/kg extract was observed. CHEE showed a higher protection against lipoperoxidation caused by FeSO₄ (82.3% TBARS inhibition) than AAPH (35.7% TBARS inhibition) at 150 μg/mL.

Conclusion

Hyptis fruticosa leaf CHEE is of pharmacological interest because it was able to inhibit the peripheral and central transmission of orofacial pain, while reducing the spreading of the inflammatory processes by neutralizing reactive oxygen species, which are by-products in the biosynthesis of pain mediators.     

Evaluation of antinociceptive effect of Aegiceras corniculatum stems extracts and its possible mechanism of action in rodents

Ethnopharmacological relevance

Aegiceras corniculatum (Linn.) Blanco is used in various traditional medicinal system(s) for the treatment of rheumatism, painful arthritis and inflammation. Therefore, the pharmacological studies of its antinociceptive effect was undertaken to validate its traditional use.

Materials and methods

n-Hexane, ethyl acetate and methanol extract(s) derived from Aegiceras corniculatum (stems) were studied using various nociceptive model(s) induced chemically or thermally in mice including acetic acid-induced writhing, formalin-induced paw licking and hot plate test.

Results

In acetic acid-induced writhing test, plant extracts dose dependently decreased the writhing numbers. The methanolic extract (1-10 mg/kg, i.p. in mice) of the plant was more potent than acetaminophen and acetyl salicylic acid, with an IC₅₀ of 4.2 ± 0.99 mg/kg. Moreover, the time of nociceptive behaviors induced by intraplantar formalin injection was also suppressed during 1st and 2nd phases in the presence of ethyl acetate extract whereas, n-hexane and methanolic extracts inhibited the paw licking in mice during the 1st (IC₅₀ 12 ± 0.76 mg/kg) and 2nd phases (IC₅₀ 3.8 ± 0.55 mg/kg). Naloxone, β-funaltrexamine, and naltrindole antagonized the n-hexane extract-induced antinociception in the first phase of formalin test indicating its non-selective analgesic response via opioid receptor(s). However, ethyl acetate extract was devoid of any opioid action. Additionally, these extracts significantly inhibited the pain stimulation in hot plate test. Withdrawal syndrome of morphine dependence was also diminished in the presence of plant extracts via potentiation of GABAergic system.

Conclusion

These results suggested that Aegiceras corniculatum extract(s) possesses analgesic properties and acts on the central nervous system, thereby suppressing the inflammatory pain justifying its folklore use.     

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., 100 mg/kg); and the flavonoid FGAL (p.o. and i.p. at 100 μmol/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 (100 mg/kg, p.o.) in the hot plate test was favorable, indicating that this fraction exhibited central activity. The ethyl acetate phase (100 mg/kg, p.o.) reduced the formalin effects in both phases by 28.51% and 55.72%, respectively. Treatment with the aqueous phase (100 mg/kg, p.o.) and FGAL (100 μmol/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 analgesic and anti-inflammatory effect of WIN-34B, a new herbal formula for osteoarthritis composed of Lonicera japonica Thunb and Anemarrhena asphodeloides BUNGE in vivo

Ethnopharmacological relevance

: Lonicera japonica Thunb and Anemarrhena asphodeloides BUNGE have been used for the treatment of a variety of inflammatory diseases, cold and infective diseases in many countries, including Korea and China.

Aim of the study

: This study aimed to assess the anti-nociceptive and anti-inflammatory activities of n-butanol fraction (WIN-34B) prepared from dried flowers of Lonicera japonica and dried roots of Anemarrhena asphodeloides as potential novel treatment of osteoarthritis.

Materials and methods

: Anti-nociceptive activities of WIN-34B (100, 200 and 400 mg/kg, p.o.) were measured using acetic acid-induced writhing response, formalin-induced paw licking, hot plate, radiant heat tail-flick, carrageenan-induced paw pressure, and Hargreaves tests, respectively. Anti-inflammatory activities of WIN-34B (100, 200 and 400 mg/kg, p.o.) were assessed using acetic acid-induced vascular permeability, carrageenan-induced paw edema, and croton oil-induced ear edema. Anti-osteoarthritis effect of WIN-34B was analyzed using monosodium iodoacetate (MIA)-induced osteoarthritis animal model.

Results

: WIN-34B exhibited better anti-inflammatory activity than that of celecoxib in carrageenan at the dose of 200 mg/kg and croton oil-induced paw edema and ear edema at the doses of 200 and 400 mg/kg. WIN-34B exhibited significant anti-inflammatory effects on vascular permeability. WIN-34B also exhibited significant anti-nociceptive activities in the late phase of formalin-induced paw licking and writhing response model in mice. In radiant heat tail-flick and carrageenan-induced paw pressure tests, WIN-34B at the dose of 400 mg/kg and at the doses of 200 and 400 mg/kg presented similar activities to indomethacin and celecoxib. Compared to indomethacin WIN-34B at 400 mg/kg showed similar or better anti-nociceptive activities after 1 and 2 h of theraphy in the hot plate test and better anti-nociceptive activity than that of celecoxib in Hargreves test. In the MIA-induced osteoarthritis animal models, WIN-34B at 400 mg/kg exhibited similar or better anti-nociceptive property than that of celecoxib throughout the pain measurement periods.

Conclusion

: When compared to celecoxib, WIN-34B exhibited similar or better anti-nociceptive and anti-inflammatory activities in osteoarthritic animal models, which may become a potential novel treatment for osteoarthritis.     

Antinociceptive effect of the essential oil of Zingiber zerumbet in mice: possible mechanisms

Ethnopharmacological relevance

Zingiber zerumbet (L.) Smith, a wild edible ginger species or locally known as “lempoyang”, commonly used in the Malays traditional medicine as an appetizer or to treat stomachache, toothache, muscle sprain and as a cure for swelling sores and cuts.

Aim

The present study was conducted to investigate the possible mechanism of actions underlying the systemic antinociception activity of the essential oil of Zingiber zerumbet (EOZZ) in chemical-induced nociception tests in mice.

Materials and methods

Acetic acid-induced abdominal constriction, capsaicin-, glutamate- and phorbol 12-myristate 13-acetate-induced paw licking tests in mice were employed in the study. In all experiments, EOZZ was administered systemically at the doses of 50, 100, 200 and 300 mg/kg.

Results

It was shown that EOZZ given to mice via intraperitoneal and oral routes at 50, 100, 200 and 300 mg/kg produced significant dose dependent antinociception when assessed using acetic acid-induced abdominal writing test with calculated mean ID₅₀ values of 88.84 mg/kg (80.88-97.57 mg/kg) and 118.8 mg/kg (102.5-137.8 mg/kg), respectively. Likewise, intraperitoneal administration of EOZZ at similar doses produced significant dose dependent inhibition of neurogenic pain induced by intraplantar injection of capsaicin (1.6 μg/paw), glutamate (10 μmol/paw) and phorbol 12-myristate 13-acetate (1.6 μg/paw) with calculated mean ID₅₀ of 128.8 mg/kg (118.6-139.9 mg/kg), 124.8 mg/kg (111.4-139.7 mg/kg) and 40.29 (35.39-45.86) mg/kg, respectively. It was also demonstrated that pretreatment with l-arginine (100 mg/kg, i.p.), a nitric oxide precursor significantly reversed antinociception produced by EOZZ suggesting the involvement of l-arginine/nitric oxide pathway. In addition, methylene blue (20 mg/kg, i.p.) significantly enhanced antinociception produced by EOZZ. Administration of glibenclamide (10 mg/kg, i.p.), an ATP-sensitive K⁺ channel antagonist significantly reversed antinociceptive activity induced by EOZZ.

Conclusion

Together, the present results suggested that EOZZ-induced antinociceptive activity was possibly related to its ability to inhibit glutamatergic system, TRPV1 receptors as well as through activation of l-arginine/nitric oxide/cGMP/protein kinase C/ATP-sensitive K⁺ channel pathway.     

Aqueous root extracts from Mimosa albida Humb. & Bonpl. ex Willd display antinociceptive activity in mice

Ethnopharmacological relevance

In this work, we study whether aqueous extracts from the roots of Mimosa albida Humb. & Bonpl. ex Willd, a plant known in the Highlands of Chiapas, Mexico as “Lotóm chíx” are endowed with both antinociceptive and anxiolytic effects.

Materials and methods

ICR mice were systemically treated with aqueous extracts from Mimosa albida and the reference compounds (diazepam, dipyrone and/or fentanyl) and their behavior was evaluated in several behavioral tests.

Results

Administration of aqueous extracts from the roots of Mimosa albida resulted in a reduction of the nociception elicited in mice by both the hot plate (12.5, 25 and 50 mg/kg; i.p.) and the acetic acid-induced writhing (25 and 50 mg/kg; i.p.) tests. No effects were however observed both in the elevated plus-maze and hole board test (3.2, 12.5 and 25 mg/kg; i.p.). In contrast, both locomotion (open field test) and motor coordination (rotarod test) were affected at doses (50, 100 y 200 mg/kg; i.p.) higher than those having antinociceptive effects.

Conclusion

These data suggest that in mice the systemic administration of low doses of aqueous extracts from the roots of Mimosa albida results in antinociceptive effects in several models of pain through mechanisms that do not involve the opioid system pathway. These results support the ethnopharmacological use of Mimosa albida in popular medicine.     

Identification of a new antinociceptive alkaloid isopropyl N-methylanthranilate from the essential oil of Choisya ternata Kunth

Ethnopharmacological relevance

Mexican people employed infusion of leaves of Choisya ternata Kunth for their antispasmodic and “simulative properties”.

Aim of the study

In the present study the detailed GC and GC-MS analyses of the essential oil of Choisya ternata Kunth (Rutaceae) were performed. The presence of a minor constituent isopropyl N-methylanthranilate (1) was revealed among other identified volatiles. A synthesis of 1 was undertaken in order to corroborate this find and obtain gram quantities that would allow the testing of its biological activity (peripheral and central antinociceptive activity).

Materials and methods

The oils were investigated by GC and GC-MS. Synthesized compounds were spectrally characterized (UV-Vis, IR, 1D and 2D NMR, MS). The obtained synthetic samples of compounds were assayed for peripheral and central antinociceptive activity in two models (effects on acetic acid induced writhing in mice and the hot plate test for nociception).

Results

Detailed GC and GC-MS analyses of the essential oil of Choisya ternata Kunth (Rutaceae) among 157 other identified volatiles revealed the presence of a minor constituent isopropyl N-methylanthranilate (1). Compound 1, named ternanthranin, is therefore detected as a natural product for the first time with a very restricted occurrence (samples of several citrus oils were screened for the presence of 1). The antinociceptive activities were assayed for ternanthranin, the two other synthetic analogs, methyl and propyl N-methylanthranilate, as well as the essential oil and the crude ethanol extract of the leaves. The results clearly demonstrate a very high (even significant at 0.3 mg/kg) dose dependent activity for the anthranilates (and the extracts). Isopropyl N-methylanthranilate showed the highest, while methyl N-methylanthranilate showed the lowest activity (with the methyl ester at 3 mg/kg still better than acetylsalicylic acid, at 200 mg/kg, in the first, or comparable with morphine, at 5 mg/kg, in the second test).

Conclusion

This study once again revealed that detailed investigations of plant species with ethnopharmacologically documented activity may yield new natural compounds—a new alkaloid (ternanthranin), a volatile simple anthranilate that can be considered responsible for the antinociceptive activity of the crude plant extracts.     

Antinociceptive effect of extracts and compounds from Hofmeisteria schaffneri

Ethnopharmacological relevance

Hofmeisteria schaffneri (Asteraceae) is a medicinal plant widely commercialized in the most important Markets of Mexico City for the treatment of gastro-intestinal complaints and skin afflictions.

Aim of the study

The main goals of this study were to establish the potential acute toxicity and the antinociceptive activity in animal models of several preparations and compounds from Hofmeisteria schaffneri.

Materials and methods

The aqueous and organic extracts as well as the essential oil of Hofmeisteria schaffneri were prepared by infusion, maceration and hydrodistillation, respectively. Investigation of the acute toxicity was accomplished by the Lorke method. The antinociceptive effect was assessed using the writhing and the hot plate tests. Natural compounds were isolated by standard phytochemical procedures. In addition, a few thymol esters were prepared by chemical synthesis. The stability of natural and synthetic esters was qualitatively analyzed by measuring their susceptibility to hydrolysis by pig liver estearase and mouse plasma at 37 °C.

Results

The LD₅₀ for each preparation tested was higher than 5000 mg/kg revealing that they were not toxic to mice after exposure for short space of time. On the other hand, the extracts showed significant antinociceptive effect when tested in the hot plate model. The most active natural product as antinociceptive agent was hofmeisterin III (1) which also was the most stable in the stability study. Its pharmacological effect seems to be partially mediated by an opioid mechanism since naloxone inhibits its action. Using compound 1 as a lead molecule, several synthetic thymol esters were prepared and only compounds 13, 15 and 17 were antinoceptive at the dose of 1 mg/kg.

Conclusions

The present investigation provided evidence of the efficacy of several preparations of Hofmeisteria schaffneri as antinociceptive agents. The most active preparation was the essential oil which contained large amount of hofmeisterin III (1) and other thymol derivatives. Some novel synthetic analogs of hofmeisterin III with antinociceptive properties were discovered. The nature of the ester chain of these analogs did not have a clear impact on the antinociceptive activity. The phyto-preparations analyzed in this study were not toxic to mice according to the Lorke's test; therefore considering their long term use of the plant they might be secure for human consumption.     

Antinociceptive and antiinflammatory activities of Adiantum latifolium Lam.: Evidence for a role of IL-1β inhibition

Aim of study

Adiantum, one of the most widely distributed genera of the family Pteridaceae, is employed in folk medicine worldwide. Adiantum latifolium Lam. has been used in Latin American traditional medicine as anxiolytic, analgesic and antiinflammatory. The present study investigates the antinociceptive and antiinflammatory properties of the methanolic extract of Adiantum latifolium (MEA) in animal models of pain and inflammation to confirm its medicinal use.

Material and methods

The antinociceptive and antiinflammatory activities of MEA were evaluated using the writhing, formalin, and tail-flick tests, carrageenan-induced paw edema and arachidonic acid-induced ear edema. Mice motor performance was evaluated in the rota rod test and the acute toxicity evaluated over 14 days.

Results

Intraperitoneal (1-100 mg/kg) or oral (100-400 mg/kg) administration of MEA produced a dose-related inhibition of acetic acid-induced writhing in mouse. Furthermore, treatment with MEA (100 mg/kg) inhibited both the early and late phases of formalin-induced hypernociception. In contrast, MEA (100 mg/kg/IP) did not prevent the thermal nociception in the tail-flick test. In addition, MEA (100 and 200 mg/kg/IP) inhibited important events related to the inflammatory response induced by carrageenan or arachidonic acid, namely local edema and increase in tissue interleukin-1β levels. MEA (300 mg/kg/IP)-treated mice did not show any motor performance alterations. Over the study period of 14 days, there were no deaths or toxic signs recorded in the group of mice given 1000 mg/kg of MEA.

Conclusion

The results demonstrate that Adiantum latifolium has antinociceptive and antiinflammatory activities, acting through the inhibition of IL-1β production.     

Antinociceptive effect of extract of Emilia sonchifolia in mice

Aim of the study

Emilia sonchifolia (L.) DC. (Asteraceae) is a medicinal plant traditionally used in Brazilian folk medicine to treat asthma, fever, cuts, wounds and rheumatism. This study was conducted to establish the antinociceptive properties of hydroethanolic extract from aerial parts of Emilia sonchifolia in mice using chemical and thermal models of nociception.

Materials and methods

To evaluate the antinociceptive effect of Emilia sonchifolia hydroethanolic extract (EsHE) administered by oral route, peripheral (acetic acid-induced abdominal writhing and formalin), spinal (tail flick) and supra-spinal (hot plate) behavioral models of acute pain were used. High-performance liquid chromatography (HPLC) was used to determine the fingerprint chromatogram of the EsHE.

Results

The EsHE at test doses of 100 and 300 mg/kg, p.o. clearly demonstrated antinociceptive activity in all tests. The extract had a stronger antinociceptive effect than morphine. Administration of the opioid receptor antagonist, naloxone, completely inhibited the antinociceptive effect induced by EsHE (100 mg/kg). The presence of phenolic compounds in the extract of Emilia sonchifolia was confirmed using HPLC.

Conclusion

The extract of Emilia sonchifolia markedly exhibits opioid-mediated anti-nociceptive activity action in mice. Thus, may be useful in the treatment of inflammatory hyperalgesic disorders, which supports previous claims of its traditional use.     

Anti-inflammatory and antinociceptive effects of hydroalcoholic extract from Pseudobombax marginatum inner bark from caatinga potiguar

Ethnopharmacological relevance

The Pseudobombax marginatum (St Hil) Rob., Malvaceae, is mentioned in ethnobotanical studies. It is used as anti-inflammatory, for ulcers and gastritis, and back pain. To evaluate anti-inflammatory and antinociceptive activities a hydroalcoholic extract (HE) from inner bark was prepared.

Materials and methods

For the anti-inflammatory activity, carrageenan-induced paw edema and peritonitis models, and also myeloperoxidase assay were used. For the antinociceptiva activity acetic acid-induced writhing, hot plate and formalin tests were employed.

Results

The HE extract exhibited an intense inhibition in carrageenan-induced edema model and also in myeloperoxidase activity at the doses of 100 and 300 mg/kg. The leukocyte migration into the peritoneal cavity was also inhibited at the doses of 30, 100 and 300 mg/kg. A similar profile was observed against acid-induced abdominal contortions and in formalin second phase test at the doses of 30 and 100 mg/kg, but this treatment did not affect the behavior of animals in the hot plate test.

Conclusions

The experimental data of the HE from Pseudobombax marginatum show anti-inflammatory and antinociceptiva activities, confirming the indication from traditional medicine; however further studies are required to define and isolate the active anti-inflammatory and antinociceptiva components from this active specie.     

Antinociceptive and gastroprotective actions of ethanolic extract from Pluchea sagittalis (Lam.) Cabrera

Ethnopharmacological relevance

Pluchea sagittalis, an herbaceous plant widely distributed in South America, is used in folk medicine for the treatment of digestive diseases and inflammation.

Aim of the study

This study was designed to investigate the antinociceptive and gastroprotective effects of the ethanolic extract (EE) of aerial parts from Pluchea sagittalis in rodents.

Materials and methods

The antinociceptive effects of EE was evaluated in mice after oral administration in chemical tests (acetic-acid, glutamate and formalin) or by biting behavior following intrathecal administration of cytokines such as interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in mice. Furthermore, rats were treated with EE and subsequently exposed to acute gastric lesions induced by 80% ethanol. Afterwards the gastric lesion extension and the mucus levels of gastric mucosa were measured.

Results

The oral administration of EE showed a dose-dependent inhibition of acetic acid-induced abdominal constrictions and glutamate-induced pain in mice, with ID₅₀ values of 624.0 (523.0-746.0) mg/kg and 368.0 (216.0-628.0) mg/kg, respectively. In the formalin test, the EE also produced significant inhibition of the inflammatory phase, with an ID₅₀ value of 411.0 (183.0-721.0) mg/kg; however, it was ineffective in the neurogenic phase caused by formalin. In addition, oral treatment with EE caused a significant inhibition of biting behavior induced by i.t. injection of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The antinociception caused by the EE (300 mg/kg, p.o.) was not reversed by naloxone (1 mg/kg, i.p.) when assessed in the acetic acid writhing test. The EE (300-1000 mg/kg, p.o.) did not affect the motor coordination of animals in an open-field model. Oral treatment with the EE protected rats against gastric lesions induced by ethanol, with an ID₅₀ value of 55.0 (46.6-64.9) mg/kg, and increased the mucus levels of gastric mucosa to levels found in the non-lesioned group.

Conclusions

The mechanism by which the extract produced antinociception still remains unclear, but this effect seems to be primarily related to the modulation or inhibition of the action of pro-inflammatory mediators. Furthermore, these data support, at least in part, the ethnomedical use of Pluchea sagittalis.