Antinociceptive activities of a novel diarylpentanoid analogue, 2-benzoyl-6-(3-bromo-4-hydroxybenzylidene)cyclohexen-1-ol, and its possible mechanisms of action in mice.

A novel synthetic compound from the 2-benzoyl-6-benzylidenecyclohexanone analogue, namely 2-benzoyl-6-(3-bromo-4-hydroxybenzylidene)cyclohexen-1-ol (BBHC), showed pronounced nitric oxide inhibition in IFN-γ/LPS-induced RAW 264.7 cells. Based on this previous finding, our present study aimed to investigate the antinociceptive effects of BBHC via chemical and thermal stimuli in vivo. The investigation of the antinociceptive activity of BBHC (0.1, 0.3, 1.0 and 3.0 mg/kg, i.p.) was initiated with 3 preliminary screening tests, then BBHC was subjected to investigate its possible involvement with excitatory neurotransmitters and opioid receptors. The potential acute toxicity of BBHC administration was also studied. Administration of BBHC significantly inhibited acetic acid-induced abdominal constrictions, formalin-induced paw licking activity and developed notable increment in the latency time. BBHC's ability to suppress capsaicin- and glutamate-induced paw licking activities, as well as to antagonise the effect of naloxone, had indicated the possible involvement of its antinociception with TRPV1, glutamate and opioid receptors, respectively. The antinociceptive activities of BBHC was not related to any sedative action and no evidence of acute toxic effect was detected. The present study showed that BBHC possessed significant peripheral and central antinociceptive activities via chemical- and thermal-induced nociceptive murine models without any locomotor alteration and acute toxicity.

Pharmacological studies on aqueous extract of Launaea arborescens from southwest Algeria.

ETHNOPHARMACOLOGICAL RELEVANCE: Launaea arborescens, its vernacular name is Mol-albina belonging to asteracaea family origin of the southwest of Algeria. This plant is used in folk medicines to treat gastroenteritis, diabetes, child aliment and other diseases; it is taken macerated or boiled. AIM: This study aims to evaluate the anti-inflammation an analgesic activity of the aqueous extract of Launaea arborescens (AqELA) and its pathway of action. METHODS: the investigation of anti-inflammatory and analgesic effects were done using formalin test, acetic acid test. For mechanism investigation, it was used hot plate test to induce opioid receptors, a histamine and serotonin test to induce edema paw, finally, for the TRPV1 receptor, it was used the capsaicin test. RESULTS: The aqueous extract of Launaea arborescens showed a significant inhibition of abdominal writhing test 95% and 100% inhibition of licking paw using acid acetic test and formalin test respectively (EC: 47 mg/kg and 104 mg/kg). The analgesic effect of the aqueous extract of Launaea arborescens showed inhibition of sensation of pain after 120 min compared to morphine effect. The aqueous extract of Launaea arborescens reduced paw volume after 180 min and 120 min for histamine and serotonin respectively with dose-dependent. Concerning of TRPV1 receptors, the inhibition was showed at doses 100 mg and 300 mg. CONCLUSION: Our results contribute towards validation of the traditional use of Launaea arborescens for inflammation ailment.

Antinociceptive Effects of Cardamonin in Mice: Possible Involvement of TRPV1, Glutamate, and Opioid Receptors.

Pain is one of the most common cause for hospital visits. It plays an important role in inflammation and serves as a warning sign to avoid further injury. Analgesics are used to manage pain and provide comfort to patients. However, prolonged usage of pain treatments like opioids and NSAIDs are accompanied with undesirable side effects. Therefore, research to identify novel compounds that produce analgesia with lesser side effects are necessary. The present study investigated the antinociceptive potentials of a natural compound, cardamonin, isolated from Boesenbergia rotunda (L) Mansf. using chemical and thermal models of nociception. Our findings showed that intraperitoneal and oral administration of cardamonin (0.3, 1, 3, and 10 mg/kg) produced significant and dose-dependent inhibition of pain in abdominal writhing responses induced by acetic acid. The present study also demonstrated that cardamonin produced significant analgesia in formalin-, capsaicin-, and glutamate-induced paw licking tests. In the thermal-induced nociception model, cardamonin exhibited significant increase in response latency time of animals subjected to hot-plate thermal stimuli. The rota-rod assessment confirmed that the antinociceptive activities elicited by cardamonin was not related to muscle relaxant or sedative effects of the compound. In conclusion, the present findings showed that cardamonin exerted significant peripheral and central antinociception through chemical- and thermal-induced nociception in mice through the involvement of TRPV1, glutamate, and opioid receptors.

Analgesic Effect of 5-(3,4-Dihydroxyphenyl)-3-hydroxy-1-(2-hydroxyphenyl)penta-2,4-dien-1-one in Experimental Animal Models of Nociception.

Curcuminoids derived from turmeric rhizome have been reported to exhibit antinociceptive, antioxidant and anti-inflammatory activities. We evaluated the peripheral and central antinociceptive activities of 5-(3,4-dihydroxyphenyl)-3-hydroxy-1-(2-hydroxyphenyl)penta-2,4-dien-1-one (DHHPD), a novel synthetic curcuminoid analogue at 0.1, 0.3, 1 and 3 mg/kg (intraperitoneal), through chemical and thermal models of nociception. The effects of DHHPD on the vanilloid and glutamatergic systems were evaluated through the capsaicin- and glutamate-induced paw licking tests. Results showed that DHHPD significantly (p < 0.05) attenuated the writhing response produced by the 0.8% acetic acid injection. In addition, 1 and 3 mg/kg of DHHPD significantly (p < 0.05) reduced the licking time spent by each mouse in both phases of the 2.5% formalin test and increased the response latency of mice on the hot-plate. However, the effect produced in the latter was not reversed by naloxone, a non-selective opioid receptor antagonist. Despite this, DHHPD decreased the licking latency of mice in the capsaicin- and glutamate-induced paw licking tests in a dose response manner. In conclusion, DHHPD showed excellent peripheral and central antinociceptive activities possibly by attenuation of the synthesis and/or release of pro-inflammatory mediators in addition to modulation of the vanilloid and glutamatergic systems without an apparent effect on the opioidergic system.

Zerumbone alleviates chronic constriction injury-induced allodynia and hyperalgesia through serotonin 5-HT receptors.

Zerumbone, a bioactive sesquiterpene isolated from Zingiber zerumbet (Smith), has shown to exert antiallodynic and antihyperalgesic effects in neuropathic pain mice model in our recent study. The mechanism through which zerumbone alleviates neuropathic pain has yet to be elucidated. Thus, this study aimed to determine whether the serotonergic system, part of the descending pain modulation pathway, contributes to the antineuropathic effect of zerumbone. Participation of the serotonergic system in zerumbone-induced antiallodynia and antihyperalgesia was assessed using Dynamic Plantar Aesthesiometer von Frey test and Hargreaves plantar test respectively in chronic-constriction injury mice model. Administration of ρ-chlorophenylalanine (PCPA, 100mg/kg, i.p.) for four consecutive days to deplete serotonin (5-HT) prior to zerumbone administration blocked the antiallodynic and antihyperalgesic effects of zerumbone. Further investigation with 5-HT receptor antagonists methiothepin (5-HT1/6/7 receptor antagonist, 0.1mg/kg), WAY-100635 (5-HT1A receptor antagonist, 1mg/kg), isamoltane (5-HT1B receptor antagonist, 2.5mg/kg), ketanserin (5-HT2A receptor antagonist, 0.3mg/kg) and ondansetron (5-HT3 receptor antagonist, 0.5mg/kg) managed to significantly attenuate antiallodynic and antihyperalgesic effects of zerumbone (10mg/kg). These findings demonstrate that zerumbone alleviates mechanical allodynia and thermal hyperalgesia through the descending serotonergic system via 5-HT receptors 1A, 1B, 2A, 3, 6 and 7 in chronic constriction injury neuropathic pain mice.

Antiallodynic and antihyperalgesic effects of zerumbone on a mouse model of chronic constriction injury-induced neuropathic pain.

Neuropathic pain is a chronic condition that is difficult to be treated. Current therapies available are either ineffective or non-specific thus requiring newer treatment approaches. In this study, we investigated the antiallodynic and antihyperalgesic effects of zerumbone, a bioactive sesquiterpene from Zingiber zerumbet in chronic constriction injury (CCI)-induced neuropathic pain animal model. Our findings showed that single and repeated dose of intra-peritoneal administration of zerumbone (5, 10, 50, 100 mg/kg) significantly attenuated the CCI-induced neuropathic pain when evaluated using the electronic von Frey anesthesiometer, cold plate, Randall-Selitto analgesiometer and the Hargreaves plantar test. Zerumbone significantly alleviated tactile and cold allodynia as well as mechanical and thermal hyperalgesia. Our findings are in comparison to the positive control drugs thatused gabapentin (20 mg/kgi.p.) and morphine (1 mg/kgi.p.). Together, these results showed that the systemic administration of zerumbone produced marked antiallodynic and antihyperalgesic effects in the CCI-induced neuropathic pain in mice and may serve as a potential lead compound for further analysis.

Phytochemical Screening and Acute Oral Toxicity Study of Java Tea Leaf Extracts.

The term Java tea refers to the decoction of Orthosiphon stamineus (OS) Benth (Lamiaceae) leaves, which are widely consumed by the people in Europe and South East Asian countries. The OS leaves are known for their use in traditional medicinal systems as a prophylactic and curative agent for urinary stone, diabetes, and hypertension and also as a diuretic agent. The present study was aimed at evaluating its possible toxicity. Herein, the major phytochemical constituents of microwave dried OS leaf, which is the common drying process for tea sachets in the market, were also identified. The acute oral toxicity test of aqueous, 50% aqueous ethanolic, and ethanolic extracts of OS was performed at a dose of 5000 mg/Kg body weight of Sprague-Dawley rats. During the 14-day study, the animals were observed for any mortality, behavioral, motor-neuronal abnormalities, body weight, and feed-water consumption pattern. The hematological and serum biochemical parameters to assess the kidney and liver functions were carried out, along with the histological analysis of these organs. It was found that all microwave dried OS leaf extracts did not cause any toxic effects or mortality at the administered dose. No abnormality was noticed in all selected parameters in rats of both sexes as compared with their respective control groups. Thus, the possible oral lethal dose for microwave dried Java tea leaves is more than 5000 mg/Kg body weight.

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 ID(50) 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 (1.6µg/paw) with calculated mean ID(50) 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 (100mg/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 (20mg/kg, i.p.) significantly enhanced antinociception produced by EOZZ. Administration of glibenclamide (10mg/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.

Zerumbone-induced antinociception: involvement of the L-arginine-nitric oxide-cGMP -PKC-K+ ATP channel pathways.

This study investigated the antinociceptive effects of zerumbone in chemical behavioural models of nociception in mice. Zerumbone given through intraperitoneal route (i.p.) produced dose-related antinociception when assessed on acetic acid-induced abdominal writhing test in mice. In addition, the i.p. administration of zerumbone exhibited significant inhibition of the neurogenic pain induced by intraplantar (i.pl.) injection of capsaicin and bradykinin. Likewise, zerumbone given by i.p. route reduced the nociception produced by i.pl. injection of glutamate and phorbol myristate acetate (PMA). The antinociception caused by zerumbone in the acetic acid test was significantly attenuated by i.p. pre-treatment of mice with l-arginine (nitric oxide precursor) and glibenclamide (ATP-sensitive K(+) channel inhibitor). However, the antinociception of zerumbone was enhanced by methylene blue (non-specific gyanylyl cyclase inhibitor). Together, these results indicate that zerumbone produces pronounced antinociception against chemical models of nociception in mice. It also strongly suggests that the l-arginine-nitric oxide-cGMP-PKC-K(+) ATP channel pathways, the TRPV1 and kinin B2 receptors play an important role in the zerumbone-induced antinociception.

Antinociceptive activity of methanolic extract of Acmella uliginosa (Sw.) Cass.

ETHNOPHARMACOLOGICAL RELEVANCE: Acmella uliginosa (Sw.) Cass. is a medicinal herbaceous plant that is commonly used by the Malay community in Malaysia to relieve pain often associated with mouth ulcers, toothache, sore throat, and stomach ache. AIM: The study was carried out to investigate the antinociceptive effect of the methanolic extract of A. uliginosa (Sw.) Cass. flowers (MEAU) using murine models of chemicals and thermal nociception. MATERIALS AND METHODS: Chemicals (acetic acid-induced abdominal constriction and formalin-, capsaicin-, glutamate-induced paw licking test) and thermal models (hot plate test) of nociception in mice were employed to evaluate the MEAU analgesic effect. The extract was given via oral administration at doses of 3, 10, 30 and 100 mg/kg. RESULTS: It was demonstrated that MEAU produced significant antinociceptive response in all the chemical- and thermal-induced nociception models, which indicates the presence of both centrally and peripherally mediated activities. Furthermore, the reversal of antinociception of MEAU by naloxone suggests the involvement of opioid system in its centrally mediated analgesic activity. Moreover, MEAU-treated mice did not show any significant motor performance alterations. No mortality and signs of toxicity were recorded following treatment of the MEAU. CONCLUSION: The results from the present study appear to support the folkloric belief in the medicinal properties of A. uliginosa (Sw.) Cass. which against pain at both central and peripheral levels, in which the central antinociception is probably due to the participation of the opioid receptors.

Antinociceptive activity of Melicope ptelefolia ethanolic extract in experimental animals.

Melicope ptelefolia is a medicinal herb commonly used in Malaysia to treat fever, pain, wounds, and itches. The present study was conducted to evaluate the antinociceptive activity of the Melicope ptelefolia ethanolic extract (MPEE) using animal models of nociception. The antinociceptive activity of the extract was assessed using acetic acid-induced abdominal writhing, hot-plate, and formalin-induced paw licking tests. Oral administration of MPEE produced significant dose-dependent antinociceptive effects when tested in mice and rats using acetic acid-induced abdominal constriction test and on the second phase of the formalin-induced paw licking test, respectively. It was also demonstrated that MPEE had no effect on the response latency time to the heat stimulus in the thermal model of the hot-plate test. In addition, the antinociception produced by MPEE was not blocked by naloxone. Furthermore, oral administration of MPEE did not produce any effect in motor performance of the rota-rod test and in acute toxicity study no abnormal behaviors as well as mortality were observed up to a dose level of the extract of 5 g/kg. These results indicated that MPEE at all doses investigated which did not produce any sedative and toxic effects exerted pronounce antinociceptive activity that acts peripherally in experimental animals.

Antinociceptive activity of the essential oil of Zingiber zerumbet.

In the present study, the rhizome essential oil from Zingiber zerumbet (Zingiberaceae) was evaluated for antinociceptive activity using chemical and thermal models of nociception, namely, the acetic acid-induced abdominal writhing test, the hot-plate test and the formalin-induced paw licking test. It was demonstrated that intraperitoneal administration of the essential oil of Z. zerumbet (EOZZ) at the doses of 30, 100 and 300 mg/kg produced significant dose-dependent inhibition of acetic acid-induced abdominal writhing, comparable to that of obtained with acetylsalicylic acid (100 mg/kg). At the same doses, the EOZZ produced significant dose-dependent increases in the latency time in the hot-plate test with respect to controls, and in the formalin-induced paw licking test, the EOZZ also significantly reduced the painful stimulus in both neurogenic and inflammatory phase of the test. In addition, the antinociceptive effect of the EOZZ in the formalin-induced paw licking test as well as hot-plate test was reversed by the nonselective opioid receptor antagonist, naloxone suggesting that the opioid system was involved in its analgesic mechanism of action. On the basis of these data, we concluded that the EOZZ possessed both central and peripheral antinociceptive activities which justifying its popular folkloric use to relieve some pain conditions.

Antinociceptive, anti-inflammatory, and antipyretic properties of an aqueous extract of Dicranopteris linearis leaves in experimental animal models.

This study was performed out to establish the antinociceptive, anti-inflammatory, and antipyretic properties of an aqueous extract of Dicranopteris linearis leaves in experimental animals. The antinociceptive activity was measured using the abdominal constriction, hot plate, and formalin tests. The anti-inflammatory and antipyretic activities were measured using the carrageenan-induced paw edema and brewer's yeast-induced pyrexia tests, respectively. The extract, obtained after 72 h soaking of the air-dried leaves in distilled water and then prepared in the doses of 13.2, 66.0, 132.0, and 660.0 mg/kg, was administered subcutaneously 30 min before subjecting the animals to the assays mentioned above. Generally, the extract, at all doses used, was found to have significant (P < 0.05) concentration-independent antinociceptive, anti-inflammatory, and anti-pyretic activity. In conclusion, the aqueous extract of D. linearis has antinociceptive, anti-inflammatory, and antipyretic activity, supporting previous claims of its traditional use by the Malays to treat various ailments, particularly fever.

Antinociceptive and antiinflammatory activities of the aqueous extract of Trigonopleura malayana resin in experimental animal models.

Trigonopleura malayana L. (Euphorbiaceae) resin, locally known as Gambir Sarawak, has been used traditionally to alleviate pain associated with insect bites, muscle ache, toothache and minor injuries. The present study was carried out using various animal models to determine the antinociceptive and antiinflammatory activities of the T. malayana resin aqueous extract. Antinociceptive activity was measured using the abdominal constriction, hot plate and formalin tests, while antiinflammatory activity was measured using the carrageenan-induced paw edema test. The extract, obtained after 24 h of soaking the dried resin in distilled water, was prepared in doses of 0.3, 3 and 10 mg/kg and administered subcutaneously 30 min prior to the assays. The mechanism of action was also determined by prechallenging with naloxone (10 mg/kg), a nonselective opioid antagonist. The extract was found to exhibit significant (P < 0.05) and dose-dependent antinociceptive and antiinflammatory activities; naloxone failed to inhibit the former activity. In conclusion, the aqueous extract of T. malayana resin possesses nonopioid antinociceptive and antiinflammatory activities, thus supporting previous claims regarding its traditional use by the Malays to treat various ailments, particularly those related to pain.

Antinociceptive, anti-inflammatory and antipyretic properties of the aqueous extract of Bauhinia purpurea leaves in experimental animals.

OBJECTIVE: The present study was carried out to determine the antinociceptive, anti-inflammatory and antipyretic activities of the aqueous extract of Bauhinia purpurea leaves using animal models. MATERIALS AND METHODS: The air-dried, powdered leaves (approximately 20 g) were soaked in distilled water (1:20; w/v) at room temperature for 72 h and the supernatant obtained was freeze-dried. The crude dried extract (approximately 2.4 g) was prepared in doses of 6.0, 30.0 and 60.0 mg/kg, and subjected to the respective antinociceptive (abdominal constriction, hot plate and formalin tests), anti-inflammatory (carrageenan-induced paw edema test) and antipyretic (brewer's yeast-induced pyrexia test) assays. RESULTS: The results obtained indicate that the extract possessed significant (p < 0.05) antinociceptive, anti-inflammatory and antipyretic activities, which were not dependent on the doses of extract used. The highest concentration of extract was less effective as an anti-inflammatory and an antipyretic agent. CONCLUSION: This study showed that the aqueous extract of B. purpurea leaves possesses potential pharmacological activities that require further investigation and, thus, confirms the folklore use of the plant in the treatment of ailments associated with pain and inflammation.

The antinociceptive action of aqueous extract from Muntingia calabura leaves: the role of opioid receptors.

OBJECTIVE: The present study was carried out to investigate the antinociceptive activity of the aqueous extract of Muntingia calabura (MCAE) leaves and to determine the effect of temperature and the involvement of the opioid receptor on the said activity using the abdominal constriction test (ACT) and hot-plate test (HPT) in mice. MATERIALS AND METHODS: The extract was prepared by soaking the dried powdered leaves of M. calabura in distilled water (dH(2)O) overnight, and the supernatant obtained was considered as a stock solution with 100% concentration. The stock solution was diluted to 1, 5, 10, 50 and 100% and used to determine the antinociceptive activity of MCAE. A further experiment was done with 50% concentration to determine the effect of temperature and naloxone involvement of the opioid receptor system in MCAE antinociceptive activity. RESULTS: At the various concentrations MCAE showed significant antinociceptive activity in both tests. However, the concentration-dependent activity was observed only in the ACT but not in the HPT. The 50% concentration of MCAEs were also stable against the effect of various temperatures as indicated by the presence of activity in both tests. The temperatures (40, 60 and 100 degrees C) also showed an enhanced extract activity only in the HPT. Pre-treatment with naloxone (2 and 10 mg/kg) blocked the extract activity in both tests, indicating the involvement of the opioid receptor system in MCAE antinociceptive activity. CONCLUSION: Our data indicate that M. calabura leaves possess antinociceptive activity against chemically and thermally induced noxious stimuli. The bioactive compound(s) responsible for its antinociceptive activity is/are heat-stable and work partly via the opioid receptor 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.

Antinociceptive, anti-inflammatory and antipyretic effects of Solanum nigrum chloroform extract in animal models.

AIM: The present study was carried out to evaluate the antinociceptive, anti-inflammatory and antipyretic effects of chloroform extract of Solanum nigrum leaves using various animal models. METHODS: The extract was prepared by soaking (1:20; w/v) the air-dried powdered leaves (20 g) in chloroform for 72 hrs followed by evaporation (40 degrees C) under reduced pressure to dryness (1.26 g) and then dissolved (1:50; w/v) in dimethylsulfoxide (DMSO). The supernatant, considered as the stock solution with dose of 200 mg/kg, was diluted using DMSO to 20 and 100 mg/kg, and all doses were administered (s.c.; 10 ml/kg) in mice/rats 30 min prior to tests. RESULTS: The extract exhibited significant (p<0.05) antinociceptive activity when assessed using the abdominal constriction, hot plate and formalin tests. The extract also produced significant (p<0.05) anti-inflammatory and antipyretic activities when assessed using the carrageenan-induced paw edema and brewer's yeast-induced pyrexia tests. Overall, the activities occurred in a dose-independent manner. CONCLUSION: The present study demonstrated that the lipid-soluble extract of S. nigrum leaves possessed antinociceptive, anti-inflammatory and anti-pyretic properties and confirmed the traditional claims.

Antinociceptive and anti-inflammatory activities of Dicranopteris linearis leaves chloroform extract in experimental animals.

The present study was carried out to establish the antinociceptive and anti-inflammatory properties of Dicranopteris linearis leaves chloroform extract in experimental animals. The antinociceptive activity was measured using the abdominal constriction, formalin and hot plate tests, while the anti-inflammatory activity was measured using the carrageenan-induced paw edema. The extract, obtained after 72 h soaking of the air-dried leaves in chloroform followed by evaporation under vacuo (40 degrees C) to dryness, was dissolved in dimethyl sulfoxide to the doses of 20, 100 and 200 mg/kg and administered subcutaneously 30 min prior to subjection to the above mentioned assays. The extract, at all doses used, was found to exhibit significant (p<0.05) antinociceptive activity in a dose-dependent manner. However, the significant (p<0.05) anti-inflammatory activity observed occur in a dose-independent manner. As a conclusion, the chloroform extract of D. linearis possesses antinociceptive and anti-inflammatory activity and thus justify its traditional uses by the Malays to treat various ailments.

The antinociceptive activity of Muntingia calabura aqueous extract and the involvement of L-arginine/nitric oxide/cyclic guanosine monophosphate pathway in its observed activity in mice.

The present study was carried out to investigate on the possible involvement of L-arginine/nitric oxide/cyclic guanosine monophosphate (L-arginine/NO/cGMP) pathway in the aqueous extract of Muntingia calabura (AEMC) leaves antinociception in mice assessed by abdominal constriction test. The AEMC, obtained by soaking the dried leaves in distilled water (DH(2)O) (1 : 2; w/v) for 24 h, was prepared in concentrations of 10%, 50% and 100% that were approximately equivalent to doses of 27, 135 and 270 mg/kg, and administered subcutaneously (s.c.) 5 min after pre-treatment (s.c.) of mice with DH(2)O, L-arginine (20 mg/kg), N(G)-monomethyl-L-arginine acetate (L-NMMA; 20 mg/kg), N(G)-nitro-L-arginine methyl esters (L-NAME; 20 mg/kg), methylene blue (MB) (20 mg/kg), respectively. The AEMC was found to exhibit a concentration-dependent antinociception after pre-challenge with DH(2)O. Interestingly, pre-treatment with L-arginine was found to block significantly (P < 0.05) the AEMC antinociception but only at the highest concentration (100%) of AEMC used. On the other hand, pre-treatment with L-NAME was found to significantly (P < 0.05) enhance the low concentration but inhibit the high concentration AEMC antinociception. MB was found to significantly (P < 0.05) enhance AEMC antinociception at all concentrations used. Except for the higher concentration of AEMC used, co-treatment with L-NAME was found to insignificantly and significantly (P < 0.05) reverse the L-arginine effect when given alone or with low concentration AEMC, respectively. In addition, co-treatment with MB significantly (P < 0.05) reversed the L-arginine effect when given alone or with 10% concentration AEMC but failed to affect the activity of the rest of concentrations used. As a conclusion, this study has demonstrated the involvement of L-arginine/NO/cGMP pathway in AEMC antinociception.