Antinociceptive and anti-inflammatory effects of the aerial parts of Artemisia dracunculus in mice

Context: Tarragon (Artemisia dracunculus L., Asteraceae) is an ancient herb, which is widely used as a medicine, flavoring, or fragrance.

Objective: To determine the antinociceptive and anti-inflammatory effects of aerial parts of tarragon, we investigated the effects of ethanolic extract of the plant in adult male Balb/c mice.

Materials and methods: Antinociceptive activity was determined using formalin, hot-plate, and writhing tests. The effect of the ethanolic extract on acute inflammation was evaluated by xylene-induced ear edema in mice. The ethanolic extract was administered at doses of 5, 10, 50, and 100?mg/kg, i.p. The control group received saline as vehicle of ethanolic extract.

Results: Our results showed that the ethanolic extract (50 and 100?mg/kg) decreased both phases of pain in the formalin test (ED₅₀?=?109.66 and 87.13?mg/kg, respectively). In the hot-plate test, the extract (50 and 100?mg/kg) increased pain threshold during 60?min (ED₅₀?=?81.03?mg/kg). The extract (50 and 100?mg/kg) exhibited antinociceptive activity against acetic acid-induced writhing (ED₅₀?=?66.99?mg/kg). The extract (50 and 100?mg/kg) showed significant activity in the xylene ear edema test (ED₅₀?=?78.20?mg/kg). Pretreatment of the animals with naloxone decreased the analgesia induced by the extract in hot-plate and formalin tests; therefore, opioid receptors may be involved, at least partly, in the analgesic effect of tarragon extract.

Discussion and conclusion: The results suggested that tarragon have significant analgesic and anti-inflammatory effects in mice, and, therefore, further studies are required to evaluate these effects and additional potential of the plant.     

Methanol extract from mycelium of endophytic fungus Rhizoctonia sp. induces antinociceptive and anti-inflammatory activities in mice

The present study aimed to elucidate the antinociceptive and anti-inflammatory properties of the methanol extract from the mycelium of the endophytic fungus Rhizoctonia sp. (MEMRh) in mice. The antinociceptive activity was assessed using the abdominal constriction, hot plate, and formalin tests. The anti-inflammatory activity was assessed using a murine model of paw edema. Intraperitoneal administration of MEMRh (0.1, 1, 10 and 100?mg/kg, i.p.) produced an inhibition of acetic acid-induced writhing in mice for at least 8?h. In addition, all doses tested of the methanol extract were able to prevent thermal nociception in the hot-plate test. Furthermore, treatment with MEMRh (10?mg/kg, i.p.) inhibited both the early and late phases of formalin-induced nociception. This antinociceptive effect exhibited by MEMRh in the formalin test was reversed by the systemic administration of naloxone. MEMRh produced inhibition in a carrageenan-induced edema model at a dose of 10?mg/kg. The same extract also displayed significant activity against a histamine- or PGE(2)-induced edema model. The experimental data demonstrated that MEMRh showed remarkable anti-inflammatory and antinociceptive activities. Further studies are warranted to define and isolate the active anti-inflammatory and antinociceptive components from this endophytic fungus, which may yield effective agents for the treatment of inflammatory disorders.     

Antinociceptive and anti-inflammatory effects of the ethanol extract of Alpinia conchigera rhizomes in various animal models

Alpinia conchigera Griff. (Zingiberaceae), locally known to the Malays as “lengkuas ranting”, is native to Peninsular Malaysia. The Malays traditionally used it to treat infection and rashes, and as a health drink. This study evaluated the analgesic and anti-inflammatory activities of the ethanol extract of A. conchigera rhizomes in mice and rats, respectively. The analgesic activity was elucidated using the acetic acid-induced writhing test, hot plate test, and formalin test, while the anti-inflammatory activity was determined using carrageenan-induced paw edema. The extract (30, 100, and 300?mg/kg) given intraperitoneally (i.p.) exhibited antinociceptive and anti-inflammatory activities in all tests used. The range of percentage of analgesia obtained for all doses of extract in the writhing test was 50–92%, and in the early and late phases of the formalin test was 25–62% and 63–98%, respectively. In addition, naloxone (5?mg/kg) given subcutaneously (s.c.) was found to reverse the extract (300?mg/kg)-induced antinociceptive activity in the writhing, hot plate, and formalin tests. Based on the results obtained, it can be concluded that the ethanol extract of A. conchigera rhizomes possessed a peripheral and central antinociceptive activity that was mediated, in part, via the opioid receptor, as well as anti-inflammatory activity.     

Evaluation of Moringa oleifera Aqueous Extract for Antinociceptive and Anti-Inflammatory Activities in Animal Models

Moringa oleifera L. (Moringaceae) is known to possess high nutritional value and is used in a folklore medicine to treat various ailments related to pain and inflammation. The aim of the present study was to evaluate the antinociceptive and anti-inflammatory effects of the aqueous extract of the leaves of M. oleifera in laboratory animals, using the writhing, hot-plate and formalin tests as the antinociceptive assays, and carrageenan-induced paw edema test as the anti-inflammatory assay. The extract (10, 30 and 100 mg/kg) exhibited significant (P < 0.05) antinociceptive activity, which occurred in a dose-dependent manner, in all tests used. The extract also exhibited significant (P < 0.05) anti-inflammatory activity in a dose-dependent manner. Furthermore, the extract antinociceptive activity was suggested to be modulated via opioid receptors at the central, but not peripheral, antinociceptive level, based on the ability of 5 mg/kg naloxone to reverse the extract activity in the hot-plate, but not the writhing test. In conclusion, M. oleifera leaves possess peripherally non-opioid mediated and centrally opioid mediated antinociceptive and anti-inflammatory activities. This study also confirms the traditional uses of M. oleifera in the treatment of ailments, particularly those related to pain and inflammation.     

Antinociceptive effects of (O-methyl)-N-benzoyl tyramine (riparin I) from Aniba riparia (Nees) Mez (Lauraceae) in mice

The present study examined the antinociceptive effects of (O-methyl) N-benzoyl-tyramine (riparin I, ripI) isolated from the unripe fruit of Aniba riparia in chemical and thermal behavioral models of pain, such as acetic acid-induced abdominal writhing, formalin, and hot-plate tests in mice. Moreover, the involvement of the nitric oxide pathway as well as the opioid system in the antinociceptive action of ripI in the formalin test was investigated. RipI was administered both orally and intraperitoneally to male mice at single doses of 25 and 50 mg/kg. In the acetic acid-induced abdominal writhing, ripI decreased the number of writhings at both doses. In addition, in the formalin test, ripI reduced the paw licking time at both phases of the test. The effect of the highest dose of ripI in mice formalin test on the early phase was not reversed by naloxone (opioid receptor antagonist) but it was reversed by l-arginine (a nitric oxide precursor) in the late phase, suggesting that ripI may not act through opioid system and possibly acts through inhibition of nitric oxide pathway. In the hot-plate test, ripI increased the reaction time in the hot-plate test at the dose of 25 mg/kg, i.p., confirming the result found in the formalin test. Based on the obtained results, it is suggested that ripI presents antinociceptive activity that may be due to peripheral mechanisms (nitric oxide pathway) and central mechanisms, discarding the involvement of opioid system.     

Antinociceptive and anti-inflammatory properties of Corchorus capsularis leaves chloroform extract in experimental animal models

The antinociceptive and anti-inflammatory properties of Corchorus capsularis leaves chloroform extract were investigated in experimental animal models. The antinociceptive activity was measured using the writhing, hot plate and formalin tests, while the anti-inflammatory activity was measured using the carrageenan-induced paw edema test. The extract, obtained after 72 h soaking of the air-dried leaves in chloroform followed by in vacuo evaporation to dryness, was weighed and prepared by serial dilution in DMSO in the doses of 20, 100 and 200 mg/kg. The extract was administered (s.c.) 30 min prior to subjection to the respective assays. The extract was found to exhibit significant (p < 0.05) antinociceptive and anti-inflammatory activities. As a conclusion, the present study confirmed the traditional claims of using C. capsularis to treat various ailments related to inflammation and pain.     

Analgesic and anti-inflammatory activities of the isomeric mixture of alpha- and beta-amyrin from Protium heptaphyllum (Aubl.) march

In the present work, we demonstrated that the mixture of alpha- and beta-amyrin (AMI) from Protium heptaphyllum has antinociceptive activity as was evident from the writhing and formalin tests in mice. AMI (10 and 50 mg/kg, i.p.) inhibited writhing in 73 and 94%, respectively, while preferentially inhibiting the 2nd phase of the response (37 and 51; and 60 and 73% inhibitions of the 1st and 2nd phases, respectively) to the formalin test. Naloxone, an opioid antagonist, did not reverse the antinociceptive effect. AMI (50 mg/kg, i.p.) was also active in the hot plate test, increasing the reaction time to thermal stimulus after 30 and 60 min, by 62 and 71%, respectively. A preventive antiedematogenic effect was observed in mice that had a carrageenan-induced paw edema. Paw volume was significantly and dose-dependently decreased by 39, 42 and 53%, three hours after administration of 10, 25 and 50 mg/kg doses, i.p., respectively. AMI (25 and 50 mg/kg, i.p.) was also able to reverse the edema already induced by carrageenan (curative effect). AMI (10 and 25 mg/kg, i.p.) was equally effective in the dextran- induced paw edema (preventive effect), reducing the paw volume by 50 and 60% at the 2nd hour, and by 63 and 73% at the third hour post-dose. AMI (50 mg/kg, i.p.) reverted the edema already formed after the dextran injection (curative effect). In conclusion, AMI demonstrated peripheral and central analgesic effects independent of the opioid system, and also showed a potent anti-inflammatory activity. The antiinflammatory activity was potentiated by both indomethacin and thalidomide, suggesting a potential involvement of prostaglandins and TNFalpha inhibitions.     

Peripheral and central antinociceptive effects of the butanolic fraction of <Emphasis Type="Italic">Byrsonima verbascifolia</Emphasis> leaves on nociception-induced models in mice

Byrsonima verbascifolia (Malpighiaceae), commonly known as ‘murici’, is used in folk medicine, for example, in the treatment of inflammation. The anti-inflammatory activity of the butanolic fraction of B. verbascifolia leaves (BvBF) was previously reported by our group, and the present study was designed to evaluate their antinociceptive effects. BvBF (25, 50, and 100 mg/kg) administered intraperitoneally (i.p.) inhibited acetic acid induced abdominal writhing. In the formalin test, BvBF (10, 30 and 100 mg/kg, i.p.) caused a reduction in licking time in both the neurogenic and inflammatory phases. Moreover, we demonstrated that BvBF (30 and 100 mg/kg, i.p.) caused an increase in the latency to response in the hot-plate test. These results demonstrate that BvBF possesses marked peripheral and central antinociceptive activities. Pre-treatment with the non-selective receptor antagonist naloxone (5 mg/kg, i.p.) abolished the antinociceptive effects of BvBF (100 mg/kg, i.p.) in the neurogenic phase of the formalin and hot-plate tests. The anti-inflammatory activity of BvBF (previously reported) as well as the participation of the opioidergic system seems to be responsible, at least in part, for these antinociceptive effects. Finally, BvBF at the doses investigated (25, 50 and 100 mg/Kg) did not cause any toxicity signals, showing that the antinociceptive activity is devoid of sedative and hypomotility effects.     

Further antinociceptive properties of extracts and phenolic compounds from Plinia glomerata (Myrtaceae) leaves

This study describes the antinociceptive activity of extracts (methanolic (ME) and acetonic (AE)) and two phenolic compounds, 3,4,3'-trimethoxyflavellagic acid (1) and 3,4,3'-trimethoxy flavellagic acid 4'-O-glucoside (2), from Plinia glomerata leaves, against different experimental models of pain in mice. When evaluated against writhing test, by i.p. route, ME and AE presented calculated ID(50) values (and respective confidence interval) of 3.28 (1.63-6.61) and 24.79 (16.57-37.09) mg/kg, respectively. Given by the oral route at 500 mg/kg, AE and ME extracts inhibited the abdominal constrictions by 60.5% and 35.3%, respectively. In the formalin test (10 mg/kg, i.p.), AE inhibited both phases of pain (45.6% in the first phase; 99.8% in the second phase) whereas ME inhibited 47.8% the first phase, and 92.6% the second phase. In the capsaicin test both extracts showed activity, with calculated ID(50) values of 6.56 (5.69-7.56) and 7.68 (4.94-11.93) mg/kg for AE and ME, respectively. When evaluated against the hot-plate test, both extracts demonstrated activity, but only in high doses. Compound 2, when evaluated against the formalin test (10 mg/kg, i.p.), inhibited both phases of pain (77.6%, first phase; 62%, second phase) whereas 1 inhibited only the first phase, with inhibition of 70%. When tested in the capsaicin and glutamate tests, at 10 mg/kg, i.p., 1 and 2 caused inhibitions of 41.5% and 37.9%, and 37.7% and 54.5%, respectively. These results confirm previous studies carried out by our research group regarding the antinociceptive properties of P. glomerata, stimulating other studies on mechanism of action as well as the determination of additional active principles in this plant.     

Analgesic, antiinflammatory and central depressor effects of the hydroalcoholic extract and fractions from Aeolanthus suaveolens

This work studied antinociceptive, antiedematogenic and central depressor effects of the hydroalcoholic extract (HAE) from Aeolanthus suaveolens and its fractions: hexane (ASHAE-H), ethyl acetate (ASHAE-A), aqueous (ASHAE-E) and precipitate (ASHAE-PPT) in experimental models in mice. The highest activity in the writhing test was presented by ASHAE-A followed by ASHAE-PPT and ASHAE-E and the lowest by ASHAE-H. In the formalin test the effect was manifested at both phases, although more intensely at the 2nd phase of the response. In this test, the most active fraction was ASHAE-PPT causing inhibitions of the order of 76 and 90% of the 2nd phase of the test at the doses of 10 and 100 mg/kg i.p., respectively. Naloxone reversed the effects of ASHAE-PPT in both phases of the test, suggesting the participation of the opioid system in the antinociceptive effect. On the other hand, the HAE effect on both phases of the formalin test was only partially reversed by naloxone, suggesting that the extract presents more than one active compound, and at least one, of a polar nature, acting through the opioid system. HAE and ASHAE-PPT presented antiinflammatory activity and were very effective in decreasing the mouse paw edema induced by carrageenan. All fractions significantly decreased locomotor activity in the open field test in mice. However, only the nonpolar fractions presented myorelaxant activity as demonstrated by the rota rod test.     

Antiinflammatory,Analgesic and Antipyretic Activities of Aerial Parts of Costus speciosus Koen

In the present study, methanol extracts of Costus speciosus Koen. aerial parts were assessed for antiinflammatory, analgesic and antipyretic activities in experimental animals. The antiinflammatory activity of methanol extract of Costus speciosus (400 and 800 mg/kg, p.o.) was evaluated using carrageenan-induced paw oedema test. Analgesic effect was evaluated using acetic acid-induced writhing and Eddy’s hot-plate models and antipyretic activity was assessed by Brewer’s yeast-induced pyrexia in rats. The methanol extract of aerial parts of Costus speciosus in a dose of 400 and 800 mg/kg showed significant antiinflammatory activity (19.36 and 40.05% reduction) at 5 h postmedication. In analgesic models extract treated animals at (400 and 800 mg/kg) inhibited writhing’s caused by acetic acid by 14.24 and 31.90%, respectively, and it also increased the latency period at both high and low doses which showed the mean reaction time at 16.60±0.355 s and 14.12±0.355 s, respectively, when compared to control in hot-plate test. It also reduces the rectal temperature of the animals at low and high doses significantly 37.03±0.108° and 36.63±0.098°, respectively, in Brewer’s yeast induced pyrexia. The obtained results of the present investigation revealed that methanol extract of Costus speciosus has significant antiinflammatory, analgesic and antipyretic activities.     

Antinociceptive Activity of Aqueous and Alcohol Extract of Evodia Rutaecarpa

Water, methanol and ethanol extracts of Evodia rutaecarpa were tested for antinociceptive activity, which were correlated with the contents of evodiamine, rutaecarpine and evodine. Determination of contents was achieved by chromatographic techniques. Extracts were evaluated for antinociceptive activities using hot-plate test; acetic acid-induced writhing test and formalin test. All three extracts of Evodia rutaecarpa showed antinociceptive activities but the ethanol extract exhibited better effect. The better antinociceptive activity appeared to be related to higher contents of evodiamine, rutaecarpine and evodine in ethanol extract of Evodia rutaecarpa.     

Antinociceptive effects of the extracts of <Emphasis Type="Italic">Xylopia parviflora</Emphasis> bark and its alkaloidal components in experimental animals

In the present study, we attempted to elucidate the antinociceptive activity of Xylopia parviflora bark using the acetic acid-induced writhing test, hot plate test, and formalin test in mice. The MeOH extract (100 and 200 mg/kg, administered intraperitoneally (i.p.)) had an antinociceptive effect demonstrated by its inhibitory effects on writhing number induced by acetic acid. Three alkaloidal fractions exhibited significant antinociceptive effects in three animal models; the chloroform-soluble fraction, including secondary and tertiary alkaloids, exhibited the strongest effect. This result supported its use in folk medicine as an analgesic agent. We tested the main alkaloids of these fractions for their antinociceptive effects to clarify the active components. (+)-Corytuberine (6.3 and 12.5 mg/kg, i.p.) showed very strong activity, had a significant antinociceptive effect in the acetic acid-induced writhing test (with 49.4 and 98.9% reduction of writhes), in the hot plate test, and in the formalin test (with 55.4 and 90.6% inhibition during the first phase, and 73.9 and 99.9% during the second phase, respectively). (+)-Glaucine (12.5 and 25 mg/kg, i.p.) showed strong activity in three animal models, too. The activity of these compounds was also observed following oral administration in the acetic acid-induced writhing test.     

Study of anti-inflammatory and antinociceptive activity of hydroalcoholic extract of Schima wallichii bark

Hydroalcoholic extract of Schima wallichii Choisy. (Ternstroemiaceae) bark (HESW) was investigated for its anti-inflammatory, antinociceptive, and antipyretic activities. The anti-inflammatory effects of the HESW were assayed by using carrageenan and dextran (acute model) induced paw edema and cotton pellet granuloma assay (chronic model) in experimental rats. Oral administration of HESW at the doses of 150 and 300?mg/kg caused dose-dependent inhibition of carrageenan and dextran induced inflammation. HESW at the doses of 150 and 300?mg/kg caused significant dose-dependent reduction of the granuloma tissue formation in experimental rats. The extract at the oral doses of 50 and 100?mg/kg body weight exhibited significant central and peripheral analgesic activity in acetic acid induced writhing test and hot-plate test respectively in experimental mice. Treatment with HESW at the oral doses of 150 and 300?mg/kg body weight significantly reduced the yeast-provoked elevated body temperature in experimental rats in a dose-dependent manner.     

Antinociceptive effect of Lafoensia pacari A. St.-Hil. independent of anti-inflammatory activity of ellagic acid

This study was performed to determine the antinociceptive and anti-inflammatory activities of ethanolic extract of Lafoensia pacari A. St.-Hil. (PEtExt) stem bark and its fractions using various animal models such as acetic acid-induced abdominal writhing, formalin-induced pain and croton oil-induced ear edema tests. The PEtExt inhibited the acetic acid-induced abdominal writhing, reduced the pain reaction time on both phases of the formalin test and decreased the edema in a dose-dependent manner. Pre-treatment with naloxone did not reverse the antinociceptive effect. Only the ethyl acetate fraction showed antinociceptive and anti-inflammatory effects. Our results also showed that this extract contains compounds with analgesic action independent of anti-inflammatory activity.     

Analgesic and anti-inflammatory activities of Nicotiana rustica total extract

The antinociceptive and anti-inflammatory activities of Nicotiana rustica Linn. (Solanaceae) total extract (NRTE) have been studied using chemical and thermal models in mice. NRTE was obtained by methanol extraction of dried leaves of N. rustica and was administered intraperitoneally at doses of 2.5, 5, 8.5, and 12?mg/kg body wt (bw). It showed significant protective effects against chemical stimuli in the acetic acid and formalin tests. The extract also showed an inhibitory effect in xylene-induced ear edema compared with the reference drug, diclofenac, and produced a significant increase of the latency time of the reaction in the hot-plate test. Furthermore, the antinociceptive effect of NRTE (at a dose of 12?mg/kg bw) was suppressed by naloxone (a non-specific antagonist of opioid receptors) in hot-plate and formalin tests. This is the first report on the analgesic properties of this plant. The extract might act through an opioid-mediated mechanism. These findings suggest that central and peripheral mechanisms are both involved in the analgesic and the anti-inflammatory effects of N. rustica.     

Analgesic activity of the methanolic extract and total alkaloids of Glaucium paucilobum

The species of Glaucium have been used in Iranian herbal medicine as laxative, hypnotic, narcotic, and antidiabetic agents and also in the treatment of dermatitis. The analgesic activity of the aerial parts of Glaucium Freyn (Papaveraceae), a native plant of Iran, were studied using formalin, hot plate, and writhing tests in rodents. The methanolic extract and total alkaloids of Glaucium paucilobum caused graded inhibition of both phases of formalin-induced pain. In the hot plate test, i.p. administration of G. paucilobum extract at the doses of 50-90 mg/kg and total alkaloids at the dose of 10-60 mg/kg significantly raised the pain threshold at an observation time of 30 min in comparison with control (p < 0.001). In the writhing test, the extract at the doses of 30-90 mg/kg and total alkaloids at the doses of 10-60 mg/kg produced a significant decrease in the number of writhings in comparison with the control group (p < 0.001). The methanolic extract and total alkaloids of G. paucilobum, at antinociceptive doses, did not affect the motor coordination of animals when assessed in the rotarod model. The results showed that analgesic activity of this plant may be related partly to the alkaloids.     

Antinociceptive, antiinflammatory and antidiabetic effects of Leonotis leonurus (L.) R. BR. [Lamiaceae] leaf aqueous extract in mice and rats

The present study was undertaken to investigate the antinociceptive, antiinflammatory, and antidiabetic properties of the aqueous leaf extract of Leonotis leonurus (L.) R. BR. (Lamiaceae) in mice and rats, to scientifically appraise some of the plant's ethnomedical uses, and its safety and efficacy. The leaf powder of the plant was Soxhlet extracted with distilled water and used. The antinociceptive effect of the plant's extract was evaluated by the "hot-plate" and "acetic acid" test models of pain in mice, while the antiinflammatory and antidiabetic effects of the leaf extract were investigated in rats, using fresh egg albumin-induced paw edema, and streptozotocin (STZ)-induced diabetes mellitus, respectively. Morphine (MPN, 10 mg/kg i.p.), diclofenac (DIC, 100 mg/kg i.p.), and chlorpropamide (250 mg/kg p.o.) were used, respectively, as reference analgesic, antiinflammatory, and hypoglycemic agents for comparison. L. leonurus leaf aqueous extract (LLE, 50-800 mg/kg i.p.) produced dose-dependent and significant (p < 0.05-0.001) antinociceptive effects against thermally and chemically induced nociceptive pain stimuli in mice. LLE (50-800 mg/kg i.p.) also significantly (p < 0.05-0.001) inhibited fresh egg albumin-induced paw edema, and caused significant (p < 0.05-0.001) hypoglycemic effects in rats. It is suggested that the analgesic effects of LLE (50-800 mg/kg i.p.) may be peripherally and centrally mediated. The different flavonoids, diterpenoids, polyphenolics, and other chemical constituents of the plant may be involved in the observed antinociceptive, antiinflammatory, and antidiabetic effects of the plant's extract. However, the results of this experimental animal study suggest that the aqueous leaf extract of L. leonurus possesses antinociceptive, antiinflammatory, and hypoglycemic properties, and thus lend pharmacological credence to the suggested folkloric uses of the herb in the management and/or control of painful, arthritic, and other inflammatory conditions, as well as for adult-onset, type-2 diabetes mellitus in some communities of South Africa.     

The validation of Calophyllum brasiliense (“guanandi”) uses in Brazilian traditional medicine as analgesic by in vivo antinociceptive evaluation and its chemical analysis

Calophyllum brasiliense is used as anti-inflammatory and analgesic in Brazilian traditional medicine. Thus, the main purpose of this study is to evaluate the antinociceptive effect of the chloroform fraction of C. brasiliense (CFCB) roots and to investigate its main mechanism of action. The antinociceptive effect of CFCB was evaluated in mice using acetic acid-induced writhing, formalin-induced paw licking, and hot-plate tests and capsaicin- and glutamate-induced nociception. Brasiliensic acid and 1,2-dimethoxyxanthone were isolated and evaluated in writhing test. The amount of 1,2-dimethoxyxanthone was determined in the fraction by UPLC-DAD. CFCB inhibited abdominal constrictions induced by acetic acid up to 97%, with an ID₅₀ of 9.4 mg/kg (i.p.) and 131.8 mg/kg (p.o.). In the formalin test, CFCB impaired paw licking with an ID₅₀ of 26.3 mg/kg for the first phase and 27.5 mg/kg for the second phase (i.p.). The painful response evoked by capsaicin and glutamate was significantly reduced (ID₅₀ 26.7 and 47.9 mg/kg, i.p.). The latency time was increased up to 76% at 60 mg/kg (i.p.) in the hot-plate test. 1,2-Dimethoxyxanthone was almost three times more potent (ID₅₀ 27.6 μmol/kg, i.p.) than brasiliensic acid (72.0 μmol/kg) in acetic acid-induced writhing test. The amount of the xanthone was estimated as 92.5 mg/g in the extract. CFCB inhibited the nociceptive response associated to several agents. TRPV1 channels play an important role in the mechanism of action of the fraction. In addition, 1,2-dimethoxyxanthone largely contributes to the antinociceptive effect of CFCB.

     

Antinociceptive activity of Vitex-negundo Linn leaf extract

Tail flick test in rats and acetic acid induced writhing in mice were employed to study the antinociceptive activity of ethanolic leaf extract of Vitex-negundo (VN) (100, 250 and 500 mg/kg, p.o). The effect was compared with meperidine (40 mg/kg, sc) in tail flick method and aspirin (50 mg/kg, p.o) in writhing test as a standard control respectively. An interaction with naloxone hydrochloride was also studied in tail flick method for its mechanism of central analgesic action. The test drug showed significant analgesic activity in dose dependant manner in both the experimental models. In comparison to standard drug (meperidine), more than ten times dose of VN extract was required to produce comparable significant antinociceptive activity. The sub-effective dose (5 mg/kg, po) of VN potentiated the analgesic activity of meperidine (4 mg/kg, sc) and aspirin (25 mg/kg, po). Naloxone (1 mg/kg, sc) did not reverse the analgesic effect of VN extract. Our observations suggest that VN possesses both central and peripheral analgesic activity. The central analgesic action does not seem to be mediated through opioid receptors. It, may prove to be a useful adjuvant therapy along with standard analgesic drug.