Anti-inflammatory and analgesic properties of the leaf extracts and essential oil of Lavandula angustifolia Mill

Extracts obtained from the leaves of Lavandula angustifolia Mill. (Lamiaceae) are used in Iranian folk medicine as remedies for the treatment of various inflammatory diseases. For evaluation of its probable analgesic and anti-inflammatory effects, hydroalcoholic extract, polyphenolic fraction and essential oil of the leaves of the herb were prepared and their analgesic effects were studied in mice using formalin and acetic acid-induced writhing tests. Carrageenan test in rats was used for assessment of anti-inflammatory activity of above-mentioned fractions. Results showed that while the hydroalcoholic extract (400-1600 mg/kg, p.o.) inhibited only the second phase of formalin test, the polyphenolic fraction (800 and 1600 mg/kg, p.o.) and essential oil (100 and 200 mg/kg, p.o.) suppressed both phases. In acetic acid-induced writhing test, polyphenolic fraction (400 and 800 mg/kg, p.o.) and essential oil (100 and 200 mg/kg, p.o.) reduced the number of abdominal constrictions. Essential oil at a dose of 200mg/kg also inhibited carrageenan-induced paw edema. Results of the present study confirm the traditional use of Lavandula angustifolia for the treatment of painful and inflammatory conditions and calls for further investigations to determine the active chemical constituent(s).     

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 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 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.     

Anti-inflammatory and analgesic properties of Heracleum persicum essential oil and hydroalcoholic extract in animal models

Ethnopharmacological relevance

Fruits of Heracleum persicum (Apiaceae) are used as pain killer in Iranian folkloric medicine.

Aims of study

To evaluate the anti-inflammatory and analgesic effects of the hydroalcoholic extract and essential oil of the plant fruits and analyzing the essential oil.

Materials and methods

Essential oil and hydroalcoholic extracts of the fruits were prepared according to standard methods and the components of essential oil were identified using GC–MS method. The acetic acid-induced writhing response and formalin test were used in male mice to assess analgesic activity. For evaluation of anti-inflammatory effect, carrageenan-induced rat paw edema was used.

Results

Hexyl butyrate (56.5%), octyl acetate (16.5%), hexyl 2-methylbutanoate (5.2%) and hexyl isobutyrate (3.4%) were identified as the major constituents of the oil. Oral or intraperitoneal administration of Heracleum persicum essential oil (HPEO) at doses of 50–200 mg/kg and Heracleum persicum hydroalcoholic extract (HPHE) at doses of 250 and 500 mg/kg significantly reduced acetic acid-induced abdominal constrictions. HPEO and HPHE also significantly attenuated the pain response of the second phase of formalin test.In carrageenan test HPEO at doses of 100 and 200 mg/kg and HPHE at a dose of 400 mg/kg induced a significant reduction of paw edema.

Conclusions

These results clearly show the analgesic and anti-inflammatory effects of the plant essential oil and hydroalcoholic extract. Further studies are needed to clarify the mechanism of action and the components responsible for these pharmacological effects.     

Antinociceptive and antiedematogenic effects of the aqueous extract of Hyptis pectinata leaves in experimental animals

The aqueous leaf extract of Hyptis pectinata (L.) Poit (Lamiaceae), popularly known in Brazil as "sambaicatá" or "canudinho", was tested for its antinociceptive effects using the abdominal writhing, hot plate and formalin test models, and for its aniedematogenic effects using the carrageenin and arachidonic acid-induced rat paw edema. The aqueous extract of Hyptis pectinata administered orally at doses of 100, 200 and 400 mg/kg had a significant antinociceptive effect in the test of acetic acid-induced abdominal writhing, with 43, 51 and 54% reduction of writhes, respectively, compared to the control. An increase in hot-plate latency of 47 and 37.5% was also observed in animals receiving doses of 200 and 400 mg/kg, p.o. when placed on a hot plate. In the formalin test, doses of 200 and 400 mg/kg, p.o. had no significant effect during the first phase of the test (0-5 min), while the dose of 200 mg/kg, p.o. reduced the nociceptive effect by 70% during the second phase (20-25 min). At the dose of 600 mg/kg, p.o., the aqueous extract inhibited carrageenin-induced rat paw edema by 34.1%, and the dose of 300 mg/kg administered intraperitoneally inhibited the rat paw edema induced by subplantar injection of arachidonic acid by 32.8%. These results suggest that the aqueous extract from the Hyptis pectinata leaves produces antiedematogenic and antinociceptive effects. The antinocipetion observed with the hot-plate test probably involves the participation of the opioid system.     

Analgesic and anti-inflammatory activity of Crinum glaucum aqueous extract.

The anti-inflammatory and analgesic effects of the aqueous extract of Crinum glaucum were evaluated in mice and rats using the carrageenan- and dextran-induced paw oedema, acetic acid-induced writhing, cold water tail flick and formalin pain tests. The extract (100-400 mg/kg) and acetylsalicylic acid (100 mg/kg) produced a significant (P<0.05) inhibition of the second phase response in the formalin pain model, while only the high dose (400 mg/kg) of the extract showed an antinociceptive effect in the first phase. The extract also showed a dose-dependent inhibition of acetic acid-induced abdominal writhes. The tail flick latency was dose dependently enhanced by the extract but this was significantly (P<0.05) lower than that produced by morphine (2 mg/kg). The extract (125-500 mg/kg) administered 1 h before or after carrageenan-induced paw swelling produced a dose dependent inhibition of the oedema. No effect was observed with the dextran-induced oedema model. The data obtained suggest that the anti-inflammatory and analgesic effects of the extract may be mediated via both peripheral and central mechanisms.     

Analgesic Effect of the Herbal Medicine Catuama in Thermal and Chemical Models of Nociception in Mice

The antinociceptive effect of the herbal medicine Catuama and the hydroalcoholic extract (HE) of each plant present in this extract were investigated in chemical and thermal models of nociception in mice. The extract of Catuama (200 mg/kg, p.o.) caused time-dependent and long-lasting antinociception against acetic acid-induced writhing, formalin and capsaicin-induced licking and also in the tail-flick and hot-plate assays. Its maximal analgesic effect was reached 6 h after its oral administration and this effect lasted for at least 12 h. When given 6 h prior to testing (100 and 200 mg/kg, p.o.), the extract elicited dose-related antinociception, but at 400 mg/kg, its analgesic effect was greatly reduced. The antinociception caused by the extract of Catauma, like those produced by morphine, was largely antagonized by naloxone. The daily administration of the extract (200 mg/kg, p.o. for 4 days) or morphine (5 mg/kg, s.c. for 4 days) produced progressive tolerance, an effect which was reverted by naloxone (5 mg/kg, i.p.). In addition, the Catuama extract showed cross-tolerance with morphine. The Catuama antinociception was not due to its non-specific effects such as muscle relaxation or sedation of animals, nor was it secondary to its antiinflammatory property. When analysed separately the hydroalcoholic extract (HE) obtained from Trichilia catigua, Paullinia cupana, Ptychopelatum olacoids, Zinziber officinalis (200 mg/kg, p.o., 6 h prior) all inhibited acetic acid-induced pain (82%±2%; 66%±2%; 42%±2% and 30%±4% of inhibition, respectively ( p <0.01). In the formalin test the HE of P. olacoids; P. cupana; T. catigua and to a lesser extent, Z. officinalis (200 mg/kg, p.o., 6 h prior) also inhibited both phases of formalin-induced pain ( p <0.01). Thus, antinociception caused by the Catuama extract seems to be dependent on the interaction of the several active principles present in these plants. The mechanisms underlying the antinociception caused by extract of herbal medicine Catuama is still not completely understood, but a significant number of these effects are related to its interaction with the naloxone sensitive opioid system. Together, the results indicate that the herbal medicine Catuama may constitute a useful therapeutic agent for the treatment of clinical pain. © 1997 by John Wiley & Sons, Ltd.     

Investigations on the antinociceptive effect of Psidium guajava leaf essential oil and its major constituents

The antinociceptive effect of leaf essential oil from Psidium guajava and its major constituents, β-caryophyllene and α-pinene was assessed using chemical (formalin and acetic acid) and thermal (hot-plate) nociceptive tests in adult male albino mice. Oral administration of 100, 200 and 400 mg/kg of essential oil produced a significant antinociceptive effect in the formalin test and at 200 and 400 mg/kg in the acetic acid- induced writhing test. Of the major components only α-pinene, but not the β-caryophyllene, demonstrated significant antinociception in the formalin test. Neither the essential oil nor the major components could exert any significant effect in the hot-plate test. Pretreatment of mice with caffeine (20 mg/kg, i.p.), significantly inhibited the antinociceptive effect of essential oil in the formalin test. Naloxone (1 mg/kg, s.c.), the opioid antagonist, however, failed to antagonize it. These results suggest that the antinociceptive effect of P. guajava essential oil is probably mediated by endogenously released adenosine. © 1998 John Wiley & Sons, Ltd.     

Antinociceptive and antiinflammatory activities of pine (Pinus densiflora) pollen extract

The study aimed to evaluate the antinociceptive and antiinflammatory activity of pine (Pinus densiflora) pollen in mice. The antinociceptive activity was determined using acetic acid-induced abdominal constriction and formalin-induced licking, and the hot plate test. Antiinflammatory effects were evaluated using carrageenan- and formalin-induced paw edema, and arachidonic acid-induced ear edema in mice. The ethanol extract of pine pollen (100 and 200 mg/kg, p.o.) produced a significant inhibition of both phases of the formalin pain test in mice, a reduction in mouse writhing induced by acetic acid and an elevation of the pain threshold in the hot plate test in mice. The pine pollen extract also produced a significant inhibition of carrageenan- and formalin-induced paw edema as well as arachidonic acid-induced ear edema in mice. The inhibitions were similar to those produced by aminopyrine and indomethacin, p.o. The different polyphenols found in pine pollen could account for the antinociceptive and antiinflammatory actions. The results obtained indicate that the extract possesses analgesic and antiinflammatory effects.     

Black cumin seed essential oil, as a potent analgesic and antiinflammatory drug

The steam-distilled essential oil of Iranian black cumin seed (Nigella sativa L.) was investigated for its composition and analgesic and antiinflammatory properties. After oil analysis by GC/MS, 20 compounds were identified in the oil, obtained in 0.4% (v/w) yield. Among them, para-cymene (37.3%) and thymoquinone (13.7%) were the major components. Acetic acid-induced writhing, formalin and light tail flick tests were used for assessment of analgesic activity. Antiinflammatory activity was evaluated using carrageenan-induced paw oedema in rats and croton oil-induced ear oedema in mice. Black cumin seed essential oil (BCSEO) was found to produce a significant analgesic effect in acetic acid-induced writhing, formalin and light tail flick tests. Naloxone, an opioid antagonist, could not reverse the analgesic effect observed in the formalin test. Although oral administration of BCSEO at doses of 100, 200 and 400 micro L/kg did not exert a significant antiinflammatory effect in the carrageenan test, i.p. injection of the same doses significantly (p < 0.001) inhibited carrageenan-induced paw oedema. BCSEO at doses of 10 and 20 micro L/ear could also reduce croton oil-induced oedema. It seems that mechanism(s) other than opioid receptors is (are) involved in the analgesic effect of BCSEO since naloxone could not reverse this effect. Both systemic and local administration of BCSEO showed antiinflammatory activity. Thymoquinone, as one of the major components of BCSEO, probably has an important role in these pharmacological effects.     

The analgesic effect of the methanolic extract of Acanthus montanus

The analgesic effect of the methanolic leaf extract of Acanthus montanus was studied in rats using the cold water tail flick assay, and in mice using the tail immersion, tail clip, acetic acid induced writhing and formalin pain tests. The results showed dose-dependent and significant (P<0.05) increases in pain threshold, at 60 min post treatment, with doses of 200 and 400 mg/kg of the extract in tail flick, tail immersion and tail clip methods. The effects of the extract were significantly (P<0.05) lower than those produced by morphine (10 mg/kg) in the same tests. The extract (100-400 mg/kg) exhibited a dose-dependent inhibition of writhing and also showed a significant (P<0.001) inhibition of both phases of the formalin pain test, but with a less intense effect on the first than on the second phase. The results indicate that the analgesic effect of Acanthus montanus methanolic extract is both centrally and peripherally mediated.     

Antinociceptive action of Ocimum sanctum (Tulsi) in mice: possible mechanisms involved

The alcoholic leaf extract of Ocimum sanctum (OS, Tulsi) was tested for analgesic activity in mice. In the glacial acetic acid (GAA)-induced writhing test, OS (50, 100 mg/kg, i.p.; and 50, 100, 200 mg/kg, p.o.) reduced the number of writhes. OS (50, 100 mg/kg, i.p.) also increased the tail withdrawal latency in mice. Naloxone (1 mg/kg, i.p.), an opioid antagonist, and DSP-4 (50 mg/kg, i.p.), a central noradrenaline depletor, attenuated the analgesic effect of OS in both the experimental models, whereas, PCPA (300 mg/kg, i.p.), a serotonin synthesis inhibitor, potentiated the action of OS on tail flick response in mice. The results of our study suggest that the analgesic action of OS is exerted both centrally as well as peripherally and involves an interplay between various neurotransmitter systems.     

The juice of fresh leaves of Boerhaavia diffusa L. (Nyctaginaceae) markedly reduces pain in mice

The decoction or juice of leaves of Boerhaavia diffusa L. (Nyctaginaceae) is used in Martinican folk medicine for its analgesic and anti-inflammatory properties. In the present investigation we studied the acute oral (p.o.) toxicity of a crude extract obtained from a lyophilized decoction (DE) and from the juice (JE) of fresh leaves. We observed no signs of toxicity up to the dose of 5000 mg/kg (p.o.) in mice. At the dose of 1000 mg/kg, neither extract altered sleeping time evoked by the administration of pentobarbital sodium (i.p.). The DE and JE of B. diffusa were assessed in standard rodent models of algesia and inflammation. We investigated the antinociceptive effect of DE and JE in chemical (acetic acid) and thermal (hot plate) models of hyperalgesia in mice. Dipyrone sodium (200 mg/kg), JE (1000 mg/kg) and DE at the same dose (p.o.), produced a significant inhibition of acetic acid-induced abdominal writhing in mice (100, 50 and 47% inhibition, respectively) when compared with the negative control (P<0.001). In the hot-plate test in mice, morphine and JE produced a significant increase in latency during the observation time. The DE, however, only raised the pain thresholds during the first period (30 min) of observation (P<0.05). The extracts of B. diffusa were also investigated for their anti-edematogenic effect on carrageenan-induced edema in mice. However, neither extract inhibited the paw edema induced in mice (P>0.05). In the acetic acid-induced abdominal writhing in mice, pre-treatment of the animals with naloxone (5 mg/kg, i.p.) significantly reversed the analgesic effect of morphine and JE but not that of DE. These data show that the active antinociceptive principle of B. diffusa is present mainly in the juice of fresh leaves and has a significant antinociceptive effect when assessed in these pain models. The mechanism underlying this analgesic effect of fresh leaves of B. diffusa remains unknown, but seems to be related to interaction with the opioid system.     

Antinociceptive effect of the essential oil from Cymbopogon citratus in mice

The essential oil (EO) from leaves of Cymbopogon citratus increased the reaction time to thermal stimuli both after oral (25 mg/kg) and intraperitoneal (25–100 mg/kg) administration. EO (50–200 mg/kg, p.o. or i.p.) strongly inhibited the acetic acid-induced writhings in mice. In the formalin test, EO (50 and 200 mg/kg, i.p.) inhibited preferentially the second phase of the response, causing inhibitions of 100 and 48% at 200 mg/kg, i.p. and 100 mg/kg, p.o., respectively. On the other hand, the opioid antagonist naloxone blocked the central antinociceptive effect of EO, suggesting that EO acts both at peripheral and central levels.     

Analgesic activity of Ugni molinae (murtilla) in mice models of acute pain

Leaf extracts of Ugni molinae Turcz. (Myrtaceae) are used in Chilean folk medicine as analgesic and anti-inflammatory. The antinociceptive effect of dichloromethane (DCM), ethyl acetate (EA) and methanol (ME) leaf extracts was assessed by intraperitoneal, oral and topical administration in writhing, tail flick, and tail formalin tests in mice. The extracts showed a dose-dependent antinociceptive activity in all the assays under different administration routes. The ED(50) values for the different tests for the DCM, EA, ME extract and reference drug (ibuprofen) were as follows. Writhing test in acetic acid (i.p. administration): 0.21, 0.37, 1.37 and 0.85mg/kg, respectively; tail flick test (oral administration): 199, 189, 120 and 45.9mg/kg. The EC(50) values for tail flick test were (topical administration): 2.0, 0.35, 1.4 and 8.2% (w/v), respectively; and the topical analgesic effects were (formalin assay) 75.5, 77.5, 31.6 and 76.5%, respectively. Ugni molinae extracts produce antinociception in chemical and thermal pain models through a mechanism partially linked to either lipooxygenase and/or cyclooxygenase via the arachidonic acid cascade and/or opioid receptors. Flavonoid glycosides and triterpenoids have been isolated from the plant and can be associated with the observed effect. Our results corroborate the analgesic effects of Ugni molinae, and justify its traditional use for treating pain.     

Antinociceptive and anti-inflammatory effects of Elaeagnus angustifolia fruit extract

In this study, probable antinociceptive and anti-inflammatory effects of Elaeagnus angustifolia fruit components, were evaluated. For evaluation of antinociceptive effects, the chronic (formalin test) and acute (tail-flick) pain models of rats were used. For the anti-inflammatory effects, the paw inflammation model was used through subcutaneous injection of 5% formalin to the paw of male rats. Water extracts of the fruit and its components in the single dose were assessed through comparison with the antinociceptive and anti-inflammatory effects of sodium salicylate (SS) as a positive control. Administration of 300 mg/kg of SS (i.p.) had no effect on tail flick latency, while 1000 mg/kg of total (i.p. and p.o.) and endocarp (i.p.) extract, increased this latency (P<0.01, P<0.001, respectively), which was not reversed by naloxone (2 mg/kg). In the formalin test, SS (300 mg/kg, i.p.) and the extract (1000 mg/kg, p.o. ) alleviated the animals nociception in the second phase, while in the first phase they were not effective. The total and endocarp extracts (1000 mg/kg, i.p.) showed a significant effect on both phases (P<0.01, P<0.001, respectively) which was also not reversed by naloxone (2 mg/kg, i.p.). In the acute anti-inflammatory test, the total extract and the aqueous extract of individual fruit components showed a significant effect (P<0.001). This anti-inflammatory effect was not significant compared with the anti-inflammatory effect of SS. Because of the extract effect on the tail-flick latency and both phases of the formalin test, the site of its analgesic action is probably central, and the mechanism of antinociceptive action of the extract are not related to the opioid system. Our phytochemical studies indicated that aqueous extract of E. angustifolia fruit contains flavonoids, terpenoids and cardiac glycosides.     

Appraisal of antinociceptive and anti-inflammatory potential of extract and fractions from the leaves of Torreya grandis Fort Ex. Lindl

Torreya grandis (Taxaceae) was studied for antinociceptive and anti-inflammatory effects. Leaves were extracted with 80% ethanol at 80 °C for 3 h and fractionated with petroleum ether, chloroform, ethylacetate and n-butanol. The aqueous ethanolic extract (aq.EE), ethylacetate fraction (EaF) and butanol fraction (BtF) at the doses of (100 and 200 mg/kg, i.g.) body weight were used for study. Evaluation of antinociceptive activity was carried out by acetic acid-induced writhing response and formalin-induced paw licking time in the first and second phases of mice. The paw edema induced by formalin- and xylene-induced ear edema were used to assess anti-inflammatory activity. It was found that Torreya grandis extract and fractions at the doses of (100 and 200 mg/kg, i.g.) were significantly attenuated the writhing responses induced by acetic acid and second phase of pain response induced by subplantar injection of formalin in mice. In addition, these extract and fractions inhibiting the formaldehyde-induced arthritis as well as xylene-induces edema prolifically. From acute oral toxicity studies no mortality was pragmatic even at highest dose (2500 mg/kg, i.g.). Furthermore, our phytochemical studies indicated that the aq. ethanolic extract of leaves contains alkaloids, flavonoids, tannins, terpenoids and saponins. The results provide justification for the folkloric uses of Torreya grandis in the treatment of analgesic and inflammatory-based diseases across the China.     

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.     

Antinociceptive and anti-inflammatory effects of Tanacetum parthenium L. extract in mice and rats

Oral administration of the feverfew (Tanacetum parthenium) extract led to significant antinociceptive and anti-inflammatory effects against acetic acid-induced writhing in mice and carrageenan-induced paw edema in rats, respectively. These responses were dose-dependent (10, 20, 40 mg/kg, p.o.). Parthenolide (1, 2 mg/kg i.p.), the active constituent of the extract also produced antinociceptive and anti-inflammatory effects. Naloxone (1 mg/kg i.p.), an opiate antagonist, failed to reverse feverfew extract and parthenolide-induced antinociception. Feverfew extract in higher doses (40, 60 mg/kg p.o.) neither altered the locomotor activity nor potentiated the pentobarbitone-induced sleep time in mice. It also did not change the rectal temperature in rats. Feverfew extract exerted antinociceptive and anti-inflammatory effects without altering the normal behaviour of the animals.