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 aqueous extract of Pachyptera hymenaea (DC.) in mice

The standardized aqueous extract of leaves of Pachyptera hymenaea (DC.) belonging to family Bignoniaceae was investigated for possible antinociceptive effect in mice. Three different models were used to study the effects of extract on nociception, namely acetic acid-induced writhing test, formalin test (paw licking test) and tail flick test in mice. The extract was administered 1h prior to pain induction in the dose range of 25, 50 and 75mg/kg orally. The extract at the given dose range reduced the acetic acid induced nociception by 44.03, 52.90 and 62.46% respectively. The extract reduced formalin effect in both the phases of experiment by 32.36, 41.94, 54.29% and 35.39, 50.17, 55.86% respectively. In the tail flick study, animals' reaction time were increased by 22.69, 38.24 and 40.26% at the above selected doses respectively at 120min after drug administration. Naloxone (2mg/kg; s.c.) significantly antagonized the effect of extract in formalin and tail flick method, while partially antagonized the effect in writhing test. However caffeine completely reverted the extract effect in both the phases of formalin test. Results of these studies revealed that the extract have significant antinociceptive activity in the used models with a possible involvement of central mechanism and adenosine system.     

Antinociceptive activity of Syzygium jambos leaves extract on rats

Syzygium jambos (L.) Alston (Myrtaceae) (syn Eugenia jambos) is a widespread medicinal plant traditionally used in sub-Saharan Africa to treat several diseases. The analgesic potential of leaf hydro-alcoholic extracts was assessed in rats. Hot plate and formalin tests were used to estimate cutaneous nociception whereas measurements of forelimb grip force were done to assess muscular nociception under normal and inflammatory conditions. In the hot plate test, Syzygium jambos extract produced a significant increase in the withdrawal response latencies in a dose-dependant manner (10-300 mg/kg i.p.) and with a maximal effect (analgesic efficacy) similar to that of morphine. The extract (100-300 mg/kg i.p.) significantly reduced pain scores in all the phases of the formalin test with an analgesic efficacy higher than that shown by diclofenac. Although the extract (300 mg/kg) did not alter grip force in intact rats, it reversed the reduction in grip force induced by bilateral injection carrageenan in the forelimb triceps. This analgesic effect of the extract on muscle hyperalgesia was not antagonized, but enhanced, by naloxone. Thus, the Syzygium jambos extract has remarkable analgesic effects on both cutaneous and deep muscle pain that is not mediated by opioid receptors.     

Antinociceptive activity of methanol extract of flowers of Impatiens balsamina

Ethnopharmacological relevance

Impatiens balsamina Linn. (Balsaminaceae), an annual herb locally called “Dopati”, is cultivated as an ornamental garden plant in Bangladesh. Flowers of the plant are used in folk medicine to treat lumbago, neuralgia, burns and scalds.

Aim of the study

This study evaluated the antinociceptive effect of the methanol extract of I. balsamina flowers (MIB).

Materials and methods

The extract was evaluated for antinociceptive activity using chemical- and heat-induced pain models such as acetic acid-induced writhing, hot plate, tail immersion and formalin test. To verify the possible involvement of opioid receptor in the central antinociceptive effect of MIB, naloxone was used to antagonize the effect. The effect of MIB on central nervous system (CNS) was also studied using hole cross and open field tests.

Results

MIB demonstrated strong and dose-dependent antinociceptive activity in all the chemical- and heat-induced mice models (p<0.05). These findings imply the involvement of both peripheral and central antinociceptive mechanisms. The use of naloxone confirmed the association of opioid receptors in the central antinociceptive effect. MIB also showed significant central nervous system depressant effect (p<0.05).

Conclusion

This study reported the peripheral and central antinociceptive activity of the flowers of I. balsamina and rationalized the traditional use of the flower in the treatment of different painful conditions.     

Antinociceptive activity of the methanolic extract of Kaempferia galanga Linn. in experimental animals

Kaempferia galanga Linn. (Zingiberaceae) presents many chemical constituents of the volatile oil extracted from the rhizome. The rhizome of Kaempferia galanga is used by people in many regions for relieving toothache, abdominal pain, muscular swelling and rheumatism. In this study we investigated the antinociceptive activity in mice and rats using acetic acid-induced writhing, formalin, hot plate and tail-flick tests. The extract at test doses of 50, 100 and 200 mg/kg, p.o. clearly demonstrated antinociceptive activity in all tests. This activity was dose- and time-dependent. The extract administered at 200 mg/kg, p.o. had a stronger antinociceptive effect than aspirin (100 mg/kg, p.o.) but less than morphine (5 mg/kg, s.c.). Naloxone (2 mg/kg, i.p.) abolished the antinociceptive action of both morphine (5 mg/kg, s.c.) and the extract (200 mg/kg, p.o.) in a similar manner. In conclusion, the methanol extract of Kaempferia galanga markedly demonstrated the antinociceptive action in experimental animals. The antinociceptive mechanisms appear to be both peripherally and centrally mediated actions and the opioid receptors are probably involved. Therefore, our studies support the use in traditional medicine of Kaempferia galanga against pain caused by various disorders.     

Antinociceptive effect from Davilla elliptica hydroalcoholic extract

Davilla elliptica St Hill (Dilleniaceae) is widely used for multiple purposes in Brazil. The aim of this study was to verify the pharmacological support of this folk use and evaluate its use as antinociceptive. The hydroalcoholic extract of the stems (100-1000 mg/kg, p.o.) induced reduction of response in the formalin test inflammatory phase in mice. This antinociceptive effect does not involve the opioidergic pathway since it was not reverted by pre-treatment with naloxone nor due to myorelaxant activity since it did not affect rota-rod and tail-flick performance. Our results indicate a participation of the nitrergic pathway and may be of particular potential importance in clinical medicine, in view of the current interest in the assessment of new medicines originated from plants.     

Antinociceptive activity of fruits extracts and “arrope” of Geoffroea decorticans (chañar)

Ethnopharmacological relevance

Geoffroea decorticans (chañar) fruits and their derivate product (arrope) have been traditionally used as food and a folk medicine for the treatment of a wide variety of diseases including bronchopulmonary disorders and to relieve dolorous process.

Aim of the study

In order to evaluate the pharmacology action of this plant, studies were performed of antinociceptive and antioxidant activities.

Materials and methods

The aqueous and ethanolic extracts and arrope of chañar were evaluated in various established pain models, including chemical nociception induced by subplantar formalin and intraperitoneal acetic acid and thermal nociception method, such as tail immersion test in rats. To examine the possible connection of the opioid receptor to the antinociceptive activity of extracts and arrope it was performed a combination test with naloxone, a non-selective opioid receptor antagonist.

Results

The aqueous extract and arrope (1000 mg/kg) caused an inhibition of the pain in formalin test in the first phase, similar to morphine and decrease in the second phase. In a combination test using naloxone, diminished analgesic activity of aqueous extract and arrope were observed, indicating that antinociceptive activity is connected with the opioid receptor. The aqueous extract and arrope, caused an inhibition of the writhing response induced by acetic acid. Central involvement in analgesic profile was confirmed by the tail immersion test, in which the aqueous extract and arrope showed a significant analgesic activity by increasing latency time. The aqueous extract showed higher antioxidant activity than the arrope, it may be due to the cooking process.

Conclusions

This study has shown that the aqueous extract and arrope of Geoffroea decorticans (chañar) fruits, does possess significant antinociceptive effects. It is further concluded that aqueous extract with maximum inhibition of free radical is the most potent extract amount tested extracts. At the oral doses tested the aqueous extract and arrope were non-toxic. The present results justifies their popular use and constitutes the first validation study of the antinociceptive action.     

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.     

Antinociceptive and anti-inflammatory activities of Aquilaria sinensis (Lour.) Gilg. Leaves extract

AIM OF THE STUDY: The analgesic and anti-inflammatory activities of the ethanol extract of Aquilaria sinensis (Lour.) Gilg. Leaves were observed in various experimental models related to nociception and inflammation, so as to provide some evidence for its traditional use. MATERIALS AND METHODS: Acetic acid-induced writhing and a hot plate test in mice were used to evaluate its analgesic activity. On the other hand, its anti-inflammatory activity was observed in xylene or carrageenan-induced edema, carboxymethylcellulose sodium (CMC-Na)-induced leukocyte migration in mice and lipopolysaccharide (LPS)-induced nitric oxide (NO) release from mouse peritoneal macrophages in vitro. RESULTS: The ethanol extract significantly inhibited acetic acid-induced writhing after single oral administration at doses of 424 and 848 mg extract/kg, and the response to the thermal stimulus in mice at the dose of 848 mg/kg. Meanwhile, the ethanol extract also remarkably lessened xylene-induced ear swelling, carrageenan-induced paw edema, and CMC-Na-induced leukocyte migration. Furthermore, the extract considerably reduced NO release from LPS-stimulated macrophages with IC50 of 80.4 mg/ml. CONCLUSION: These findings suggest that Aquilaria sinensis (Lour.) Gilg. Leaves extract present notable analgesic and anti-inflammatory activities, which support its folkloric use for some diseases related with painful and inflammatory conditions such as trauma etc.     

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.     

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.     

Anti-inflammatory and antioxidant properties of hydroalcoholic crude extract from Casearia sylvestris Sw. (Salicaceae)

Ethnopharmacological relevance

Casearia sylvestris Sw. is widely used in popular medicine to treat inflammatory conditions.

Aim of the study

To investigate the anti-inflammatory and antioxidant properties of hydroalcoholic crude extract (HCE) taken from Casearia sylvestris Sw. (Salicaceae).

Methods and results

The effect of the HCE from this plant (3–300 mg/kg) on the reduction of inflammatory response to carrageenan was investigated in pleurisy in rats (intrapleural, 2% in 0.2 mL) or paw edema in mice (intraplantar, 300 μg/20 μL, right hind paw). The plant anti-inflammatory action was assessed by its capability in inhibiting cell migration, enzymatic activity of myeloperoxidase (MPO) and production of nitrite/nitrate or edema. The in vitro antioxidant activity of this extract against lipid peroxidation and damage to proteins was assessed as possible pathways to contribute as anti-inflammatory mechanisms. Carrageenan-induced hind paw edema (739.3±11.9 μm) was reduced by HCE (30 mg/kg: 462.8±28.38 μm) to similar extents as dexametasone (365.1±16.7). In pleurisy, treatment of the animals with HCE (100 mg/kg: 0.010±0.001 mU/mg of protein) also reduced MPO activity augmented by carrageenan (0.020±0.001 mU/mg of protein) as well as leukocytes migration (carrageenan: 17.8890±2.3900 leukocytes/mL, HCE 100 mg/kg: 7.0880±9631 leukocytes/mL). Significant effects were also observed in animals treated with different doses of HCE in biochemical tests for oxidative stress analysis.

Conclusion

The anti-inflammatory and antioxidant effects of HCE from Casearia sylvestris Sw. suggests a potential therapeutic benefit of this plant in treatment of inflammatory conditions.     

Antinociceptive and anti-inflammatory effects of Thespesia populnea bark extract

The ethanolic extract of Thespesia populnea bark (TPE) was investigated for anti-inflammatory and analgesic activity at the doses (p.o.) of 100, 200 and 400mg/kg body weight. For evaluation of inflammation carrageenan-, histamine- and serotonin-induced paw edema served as acute models and formaldehyde-induced arthritis served as a chronic model in rats. The acetic acid-induced writhing response and formalin-induced paw licking time in the early and late phases of mice were used to assess analgesic activity. The higher doses of TPE (200 and 400mg/kg, p.o.) were inhibiting carrageenan, histamine and serotonin-induced paw edema as well as formaldehyde-induced arthritis successfully. In addition, TPE (200 and 400mg/kg, p.o.) significantly attenuated the writhing responses induced by an intraperitoneal injection of acetic acid and late phase of pain response induced by an subplantar injection of formalin in mice. Furthermore, our phytochemical studies indicated that the ethanolic extract of bark contains alkaloids, carbohydrates, protein, tannins, phenols, flavonoids, gums and mucilage, saponins and terpenes. From acute oral toxicity studies (OECD-423 guidelines), no mortality was observed even at highest dose of TPE (2000mg/kg, p.o.).     

Antinociceptive activity of Amaranthus spinosus in experimental animals

Aim of the study

50% ethanol extract (ASE) of Amaranthus spinosus (whole plant) has been evaluated for antinociceptive and antiinflammatory activities.

Materials and methods

Analgesic and antiinflammatory activities were studied by measuring nociception by formalin, acetic acid, hot plate, tail immersion method while inflammation was induced by carrageenan.

Results

ASE had significant dose dependent percentage protection against acetic acid (0.6% of 10 ml) induced pain and the effects were also compared to aspirin, morphine and naloxone while formalin induced pain (0.05 ml of 2.5%) was significantly blocked only at higher dose (400 mg/kg) in first phase. ASE significantly blocked pain emanating from inflammation at all the doses in second phase. The reaction time in hot plate was increased significantly and dose dependently where as pretreatment with naloxone rigorously reduced the analgesic potentials of ASE. Further in tail immersion test the same dose dependent and significant activity was observed. Aspirin had no effect on thermal induced pain i.e. hot plate and tail immersion tests but showed an effect on writhing test.

Conclusions

Our investigation show that Amaranthus spinosus possess significant and dose dependant antiinflammatory activity, it has also central and peripheral analgesic activity.     

Evaluation of the analgesic effect of alkaloid extract of Peganum harmala L.: possible mechanisms involved

The seeds of Peganum harmala L. (Pgh) (Zygophyllaceae) have been used in Moroccan traditional medicine for treatment of a various diseases and to relieve dolorous process. The major objective of this paper was to investigate the mechanism of the analgesia induced by alkaloid extract of Peganum harmala. In the present work, the antinociceptive action was assayed in several experimental models in mice: writhing, formalin, and hot plate tests. The alkaloid extract (12.5 and 25mg/kg) and in a dose-dependent manner significantly reduced the nociception by acetic acid intraperitoneal injection (p<0.001). In the formalin test, the extract also significantly reduced the painful stimulus in both phases of the test (p<0.001). Treatment with the extract when given by (i.p. or i.c.v.) or with morphine (10mg/kg, i.p.) produced a significant increase of the reaction time in hot plate test. These result showed that the alkaloid extract of Pgh contains active analgesic principles acting both centrally and peripherally. Furthermore, this antinociceptive effect has been avoided by naloxone at a dose of 1mg/kg in the first phase of formalin and hot plate tests indicating that this extract act partly through an opioid-mediated mechanism. In conclusion, the alkaloid extract of Peganum harmala seems to have both central and peripheral antinociceptive activities which may be mediated by opioid receptors.     

铜皮石斛花挥发性成分的GC-MS分析

目的:研究细茎石斛花中的挥发性成分。方法:水蒸气蒸馏法提取挥发油,用气相色谱-质谱联用(GC-MS)法进行成分分析,结合计算机检索对分离的化合物进行结构鉴定。结果:分离出41个色谱峰,鉴定出29个化合物,占79.05%。其中相对含量大于2.0%的有:2,4,4三甲基-二戊烯(11.17%)、5,5-二甲基-2-己烯(11.12%)、β-石竹烯(6.47%)、异土木香内酯(5.95%)、邻苯二甲酸二乙酯(4.70%)、1,3,3二甲基丁烯-1,1-二苯基(5.20%)、2,2,4三甲基-1-戊醇(4.23%)、2-甲基-N-苯基-2-丙烯(2.73%)、3-甲基丁醛(2.12%)、异长叶烯(2.03%)等。结论:应用气相色谱-质谱联用技术对细茎石斛花挥发性成分进行的分析研究表明,烯、醛、酯和醇类等挥发油成分构成了细茎石斛花的芳香特征,与铁皮石斛花的挥发油成分组成差异较大。     

阔苞菊属植物化学成分与药理活性研究进展

菊科阔苞菊属的多种植物为世界各地的民间用药,受到各国学者的广泛关注.综述阔苞菊属植物化学成分和药理活性的研究进展,其中化学成分包括桉烷型倍半萜类衍生物、噻吩环聚炔类、苯丙素类等;药理活性包括抗氧化、抗炎及神经药理学作用.以期对今后该属植物进一步研究和开发利用提供参考.     

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.     

Chemical composition, antinociceptive and anti-inflammatory effects in rodents of the essential oil of Peperomia serpens (Sw.) Loud

Ethnopharmacological relevance

Peperomia serpens (Piperaceae), popularly known as “carrapatinho”, is an epiphyte herbaceous liana grown wild on different host trees in the Amazon rainforest. Its leaves are largely used in Brazilian folk medicine to treat inflammation, pain and asthma.

Aim of the study

This study investigated the effects of essential oil of Peperomia serpens (EOPs) in standard rodent models of pain and inflammation.

Materials and methods

The antinociceptive activity was evaluated using chemical (acetic acid and formalin) and thermal (hot plate) models of nociception in mice whereas the anti-inflammatory activity was evaluated by carrageenan- and dextran-induced paw edema tests in rats croton oil-induced ear edema, as well as cell migration, rolling and adhesion induced by carrageenan in mice. Additionally, phytochemical analysis of the EOPs has been also performed.

Results

Chemical composition of the EOPs was analyzed by gas chromatography and mass spectrometry (GC/MS). Twenty-four compounds, representing 89.6% of total oil, were identified. (E)-Nerolidol (38.0%), ledol (27.1%), α-humulene (11.5%), (E)-caryophyllene (4.0%) and α-eudesmol (2.7%) were found to be the major constituents of the oil. Oral pretreatment with EOPs (62.5-500 mg/kg) significantly reduced the writhing number evoked by acetic acid injection, with an ED₅₀ value of 188.8 mg/kg that was used thereafter in all tests. EOPs had no significant effect on hot plate test but reduced the licking time in both phases of the formalin test, an effect that was not significantly altered by naloxone (0.4 mg/kg, s.c.). EOPs inhibited the edema formation induced by carrageenan and dextran in rats. In mice, EOPs inhibited the edema formation by croton oil as well as the leukocyte and neutrophil migration, the rolling and the adhesion of leukocytes.

Conclusions

These data show for the first time that EOPs has a significant and peripheral antinociceptive effect that seems unrelated to interaction with the opioid system. EOPs also displays a significant anti-inflammatory effect in acute inflammation models. This effect seems to be related to components which inhibit the production of several inflammatory mediators. These results support the widespread use of Peperomia serpens in popular medicine to treat inflammation and pain.     

Antinociceptive and anti-inflammatory activities of ethanolic extracts of Lychnophora species

Extracts from Lychnophora species are traditionally used in Brazil as anti-inflammatory, and to treat bruise, pain and rheumatism. The ethanolic extract of aerial parts of five species of Lychnophoras and one specie of Lychnophoriopsis were examined for the antinociceptive (hot-plate and writhing tests) and anti-inflammatory (carrageenan-induced paw oedema test) activity in mice, by oral and topical routes, respectively. In the hot-plate test, the Lychnophora pinaster (0.75 g/kg) and Lychnophora ericoides (1.50 g/kg) extracts significantly increased the time for licking of the paws. The species Lychnophora passerina, Lychnophoriopsis candelabrum and Lychnophora pinaster, using the dose of 0.75 g/kg, and Lychnophora ericoides and Lychnophora trichocarpha in both doses evaluated (0.75 and 1.50 g/kg) significantly reduced the number of writhes induced by acetic acid. The administration of Lychnophora pinaster and Lychnophora trichocarpha ointments, in both concentrations evaluated (5 and 10%, w/w), and Lychnophora passerina and Lychnophoriopsis candelabrum, in the concentration of 10%, significantly reduced the paw oedema measured 3 h after carrageenan administration, suggesting, for the first time, an anti-inflammatory activity upon topical administration of these species. The present work comparatively demonstrated the antinociceptive and anti-inflammatory activities of some Brazilian Lychnophoras.