Evaluation of Rhodojaponin III from Rhododendron molle G. Don on oral antinociceptive activity, mechanism of action, and subacute toxicity in rodents.

ETHNOPHARMACOLOGICAL RELEVANCE: In Chinese traditional medicine, Rhododendron molle G. Don is a recognized herb to ease pain. Rhodojaponin III (RJ-III) has been identified as the main pharmacological activity and toxic component of the herb; however, oral antinociception and mechanism of RJ-III have not yet been investigated. AIM OF THE STUDY: The significance of this study is to evaluate the effects of RJ-III on nociceptive and neuropathic pain, and to preliminarily explore the underlying mechanisms and subacute toxicity. MATERIALS AND METHODS: The antinociception of RJ-III was evaluated by hot plate, tail-immersion, acetic acid writhing, formalin test and chronic constriction injury (CCI) model in rodents. An experimental validation was conducted using whole-cell patch clamp technique based on the most likely mechanisms of action after screening and prediction by molecular docking study. In addition, the oral subacute toxicity of RJ-III was assessed. RESULTS: Behavioral experiments showed that RJ-III (0.20 mg/kg) reduced the latency of the nociceptive response in the hot plate and tail-immersion tests. Acetic acid and formalin-induced pain were significantly inhibited by RJ-III (0.10 and 0.05 mg/kg, respectively). Furthermore, 0.30 mg/kg of RJ-III improved hyperalgesia in the CCI-induced rats. Based on molecular docking results, electrophysiological experiments were used to demonstrate mild inhibition of voltage-gated sodium channel-related subtypes. Additionally, oral subacute toxicity that may cause leukopenia and abnormal liver function requires further attention in subsequent studies. CONCLUSION: RJ-III mildly blocks voltage-gated sodium channel to inhibit nociceptive pain and peripheral neuralgia, but 0.375 mg/kg and above may cause side effect after long-term oral administration.

Polysaccaride-rich extract of Caesalpina ferrea stem barks attenuates mice acute inflammation induced by zymosan: Oxidative stress modulation.

ETHNOPHARMACOLOGICAL RELEVANCE: Stem barks of Caesalpinia ferrea Mart. Ex Tul. (Caesalpiniaceae), also known as pau-ferro jucá or jucaína, are popularly used to treat contusions, diabetes, rheumatism and other inflammatory conditions in the form of tea, lick or decoction. OBJECTIVE: To evaluate the effect of the polysaccharide-rich extract obtained from C. ferrea stem barks (PE-Cf) in mice models of acute inflammation induced by zymosan and the involvement of oxidative stress biomarkers. MATERIALS AND METHODS: Mice were treated with PE-Cf (0.001, 0.01, 0.1, 1 mg/kg) by endovenous route (i.v.) or per oral (p.o.) 30 or 60 min before injection of the inflammatory stimuli zymosan (0.5 mg; intraperitoneal or subcutaneous intraplantar). The inflammatory parameters (edema, nociception, leukocyte migration) and oxidative stress markers (myeloperoxidase-MPO, malondialdehyde-MDA, nitrite, reduced glutathione-GSH, glutathione peroxidase-GPx) were evaluated in the models of paw edema (hidropletysmometry/expressed as ml or area under curve-AUC) and peritonitis (optical microscopy/expressed as n° of cells/mm3 of peritoneal fluid). Statistical analysis was performed by ANOVA, followed by Bonferroni test. RESULTS: PE-Cf (0.1, 0.01 and 1 mg/kg) dose-dependently inhibited paw edema, showing maximal effect (74%) at 1 mg/kg in the 5th (52 ± 9.6 µl vs. zymosan: 204 ± 3.6 µl). PE-Cf (1 mg/kg) also inhibited by 43% MPO activity in the paw tissues (17 ± 1 vs. zymosan: 30 ± 2.6 U/mg). Besides, 4 h after peritonitis induction, PE-Cf (1 mg/kg) reduced neutrophil migration by 84% (432 ± 45 vs. zymosan: 2651 ± 643 cells/mm3); visceral nociception by 76% (3 ± 0.6 vs. zymosan: 16 ± 4 writhes); nitric oxide by 73% (0.131 ± 0.033 vs. zymosan: 0.578 ± 0.185 NO2-/NO3-ml); MDA (98 ± 10 vs. zymosan:156 ± 21 U/ml), and increased GSH by 65% (736 ± 65 vs. zymosan: 259 ± 58 µmol/ml) and GPx by 72% (0.037 ± 0.007 vs. zymosan: 0.010 ± 0.005 U/mg protein). CONCLUSION: The polysaccharide-rich extract of Caesalpinia ferrea stem barks present anti-inflammatory and antioxidant effects in mice models of acute inflammation induced by zymosan.

Analgesic, anti-inflammatory and toxic effects of ethanol extracts of Cucumis melo and Citrullus lanatus seeds.

Plants are vital in drug discovery, since many safe and bioactive molecules have been discovered from plants in past, hence this study was designed to evaluate analgesic, anti-inflammatory and toxic effects of Cucumis melo and Citrullus lanatus. Seeds of these plants were selected due to their traditional value for medicinal use. Analgesic activity was determined in mice by Eddy's Hot plate and tail flick method, while anti-inflammatory activity was evaluated by hind paw edema method. Both seed extracts produced highly significant analgesic effects comparable to standard drugs at all three doses by both methods. The extract of C. lanatus showed significant anti-inflammatory activity at 100 mg while showed highly significant activity at 200 mg between 3 to 24 hours as compared to standard drugs. Both extracts did not reveal any mortality up to 1000mg/kg, while there was also no change in normal the gross behavior pattern of the animals at the dose of 50 and 100mg/kg, however there was increase in passivity, sedation and startle response at 200mg/kg. Analgesic and anti-inflammatory effects of extracts may be due to presence of cucurbitacin A, B or E in both seeds which are thought to inhibit COX 2. Results indicate that seeds of C. melo and C. lanatus may be effectively used as adjuvant analgesic and anti-inflammatory agents in situation of chronic pain and inflammation.

The leaves of Bougainvillea spectabilis suppressed inflammation and nociception in vivo through the modulation of glutamatergic, cGMP, and ATP-sensitive K+ channel pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Bougainvillea spectabilis is an ornamental shrub from Nyctaginaceae family, widely used in the traditional medicine in the treatment of pain, inflammation, and ulcer. Some research investigated the analgesic potential of this plant, however, the in-depth analysis of its antinociceptive properties and molecular mechanism(s) are yet to be revealed. PURPOSE OF THE STUDY: This study, therefore, investigated the antinociceptive potential of methanol extract of the leaves of B. spectabilis (MEBS) with possible molecular mechanism(s) of action using several pre-clinical models of acute and chronic pain in mice. MATERIALS AND METHODS: The dry leaf powder of B. spectabilis was macerated with 100% methanol, and then dried crude extract was used for in vivo experiments. Following the acute toxicity test with 500, 1000, and 2000 mg/kg b.w. doses of MEBS, the central antinociceptive activities of the extract (50, 100, and 200 mg/kg b.w.) were evaluated using hot plate and tail immersion tests, whereas the peripheral activities were investigated using acetic acid-induced writhing, formalin-induced licking and oedema, and glutamate-induced licking tests. Moreover, the possible involvements of cGMP and ATP-sensitive K+ channel pathways in the observed antinociceptive activities were also investigated using methylene blue (20 mg/kg b.w.) and glibenclamide (10 mg/kg b.w.), respectively. We also performed GC/MS-MS analysis of MEBS to identify the phyto-constituents and in silico modelling of the major compounds for potential molecular targets. RESULTS: Our results demonstrated that MEBS at 50, 100, and 200 mg/kg b.w. doses were not effective enough to suppress centrally mediated pain in the hot plate and tail immersion models. However, the extract was potent (at 100 and 200 mg/kg b.w. doses) in reducing peripheral nociception in the acetic acid-induced writhing and inflammatory phase of the formalin tests. Further analyses revealed that MEBS could interfere with glutamatergic system, cGMP and ATP-sensitive K+ channel pathways to show its antinociceptive properties. GC/MS-MS analysis revealed 35 different phytochemicals with potent anti-inflammatory and antinociceptive properties including phytol, neophytadiene, 2,4-Di-tert-butylphenol, fucoxanthin, and Vit-E. Prediction analysis showed high intestinal absorptivity and low toxicity profiles of these compounds with capability to interact with glutamatergic system, inhibit JAK/STAT pathway, scavenge nitric oxide and oxygen radicals, and inhibit expression of COX3, tumor necrosis factor, and histamine. CONCLUSION: Taken together, these results suggested the antinociceptive potentials of MEBS which were mediated through the modulation of glutamatergic, cGMP, and ATP-sensitive K+ channel pathways. These also suggested that MEBS could be beneficial in the treatment of complications associated with nociceptive pain.

Anti-inflammatory and antinociceptive effects of Curcuma kwangsiensis and its bioactive terpenoids in vivo and in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE: "Curcumae Radix", the dried rhizomes of Curcuma kwangsiensis documented in Chinese pharmacopoeia, has been traditionally used for the treatment of inflammatory and pain diseases, such as jaundice and red urine, cleaning the heart-fire and depression, arthralgia, and dysmenorrhea. However, according to literature surveys, anti-inflammatory and antinociceptive studies of C. kwangsiensis have been seldom reported so far. AIM OF THE STUDY: The current study focuses on the anti-inflammatory and antinociceptive effects of C. kwangsiensis and discovering the bioactive compounds for its traditional usages both in vivo and in vitro, which could provide scientific justification about its traditional use. MATERIAL AND METHODS: The anti-inflammatory and antinociceptive assays of various layers (ME, EA, AQS) from C. kwangsiensis were achieved by carrageenan-induced paw edema and acetic acid-induced writhing animal models, respectively. The most bioactive part, EA layer was further phytochemically investigated by multiple step chromatography techniques. The structures of these isolates were unambiguously elucidated by means of extensive spectroscopic and chemical methods, and comparison with corresponding data of the reported literature. Four major sesquiterpenoids (4, 6, 14, and 15) were achieved for their anti-inflammatory and antinociceptive assays by the two aforementioned animal models in vivo. All the isolated compounds were evaluated for their anti-inflammatory effects via detecting inflammatory mediator releases (COX-2, IL-1ß, and TNF-α) in RAW 264.7 macrophage cells induced by LPS. RESULTS: The ME and EA layers significantly alleviated the paw edema caused by carrageenan and decreased the number of writhes induced by acetic acid at the dose of 200 and/or 100 mg/kg in comparison to the control group (p < 0.01/0.05), and the EA layer exhibited better activity than that of ME layer. Subsequent phytochemical investigation on EA layer of C. kwangsiensis exhibited that three new terpenoid compounds (1-3), identified as (12Z,14R)-7ß-hydroxylabda-8(17),12-diene-14,15,16-triol (1), (12Z,14S)- 7ß-hydroxlabda-8(17),12-diene-14,15,16-triol (2), and (4S)-hydroxy-(8)-methoxy-(5S)-(H)-guaia1(10),7(11)-dien-12,8-olide (3), together with twenty-two known analogs were isolated. Furthermore, four major sesquiterpenoids (4, 6, 14, and 15) significantly relieved the paw edema and number of writhes at 100 and/or 50 mg/kg (p < 0.05/0.01). Likewise, the majority of sesqui- and diterpenoids isolated could remarkably inhibited the secretion of inflammatory mediators (COX-2, IL-1ß, and TNF-α) in LPS-stimulated RAW 264.7 macrophages cells at the concentration of 20 µg/mL, comparable to DXM used as the positive control. All the results suggested that EA layer from C. kwangsiensis possessed the anti-inflammatory and antinociceptive activities, and these sesqui- and diterpenoids could be the effective constituents responsible for relieving inflammation. CONCLUSION: The present studies undoubtedly determined the anti-inflammatory and antinociceptive material basis of C. kwangsiensis, including the EA layer and its precise components, which presented equivalent or better anti-inflammatory effects than that of positive control (ASP/DXM) in vivo and in vitro. These results not only would account for scientific knowledge for traditional use of C. kwangsiensis, but also provide credible theoretical foundation for the further development of anti-inflammatory and antinociceptive agents.

Anti-nociceptive and anti-inflammatory activities of ethanol extract and fractions of Morus mesozygia Stapf (Moraceae) leaves and its underlying mechanisms in rodents.

ETHNOPHARMACOLOGICAL RELEVANCE: Morus mesozygia Stapf (Moraceae), commonly known as African mulberry, is traditionally used for the treatment of inflammatory disorders such as rheumatism and dermatitis. AIM: This work aimed to evaluate the anti-nociceptive and anti-inflammatory effects of its ethanol (EEMm) extract, and ethylacetate fraction (EAFMm). METHODS: The anti-nociceptive and anti-inflammatory effect of ethanol extracts of M. mesozygia (EEMm), and its ethylacetate (EAFMm) and residual aqueous fraction (RAFMm) was evaluated in hotplate, acetic acid and formalin tests and as well in membrane stabilizing assay and carrageenan-induced paw oedema models. Mechanism of anti-inflammation of EAFMm was investigated in the carrageenan-induced air-pouch model. RESULTS: In the hot plate test of nociception, only the EAFMm showed significant (p < 0.05) anti-nociceptive activity. The extract and fractions significantly reduced number of writhing with EAFMm (400 mg/kg) showing highest inhibition (66.5%) in the acetic acid-induced writhing in mice. EEMm and EAFMm (400 mg/kg) significantly reduced the paw licking time in the early and late phases of the formalin test. The extract and fractions showed good membrane stabilizing activity comparable to indomethacin. EAFMm (100 and 400 mg/kg) showed the highest inhibition of paw oedema (53.4% and 58.1%) in the carrageenan-induced paw oedema model. The EAFMm (100 and 400 mg/kg) reduced exudate volume relative to carrageenan-control (2.64 ± 0.22, 2.08 ± 0.15 vs 3.83 ± 0.18 mL) and neutrophils (8.98 ± 1.36, 8.00 ± 0.22 vs 20.51 ± 1.14) in carrageenan-induced pouch. EAFMm significantly reduced exudate volume, pro-inflammatory cytokines and the expression of COX-2 and NFκB. CONCLUSION: M. mesozygia leaves demonstrated anti-nociceptive and anti-inflammatory activities by suppressing oxidative stress, pro-inflammatory cytokines, cyclooxygenase-2, and nuclear factor kappa B.

Antinociceptive activity of Schinus terebinthifolia leaf lectin (SteLL) in sarcoma 180-bearing mice.

ETHNOPHARMACOLOGY RELEVANCE: Schinus terebinthifolia Raddi leaves have been used in folk medicine due to several properties, including antitumor and analgesic effects. The variable efficacy and adverse effects of analgesic drugs have motivated the search for novel antinociceptive agents. It has been reported that the S. terebinthifolia leaf lectin (SteLL) has antitumor activity against sarcoma 180 in mice. AIM OF THE STUDY: This work aimed to evaluate whether SteLL would reduce cancer pain using an orthotopic tumor model. MATERIALS AND METHODS: A sarcoma 180 cell suspension was inoculated into the right hind paws of mice, and the treatments (150 mM NaCl, negative control; 10 mg/kg morphine, positive control; or SteLL at 1 and 2 mg/kg) were administered intraperitoneally 24 h after cell inoculation up to 14 days. Spontaneous nociception, mechanical hyperalgesia, and hot-plate tests were performed. Further, the volume and weight of the tumor-bearing paws were measured. RESULTS: SteLL (2 mg/kg) improved limb use during ambulation. The lectin (1 and 2 mg/kg) also inhibited mechanical hyperalgesia and increased the latency time during the hot-plate test. Naloxone was found to reverse this effect, indicating the involvement of opioid receptors. The tumor-bearing paws of mice treated with SteLL exhibited lower volume and weight. CONCLUSION: SteLL reduced hyperalgesia due to sarcoma 180 in the paws of mice, and this effect can be related to its antitumor action.

Oral treatments with a flavonoid-enriched fraction from Cecropia hololeuca and with rutin reduce articular pain and inflammation in murine zymosan-induced arthritis.

ETHNOPHARMACOLOGICAL RELEVANCE: Cecropia Loefl. species (Urticaceae) are widely spread across the rainforest in tropical and subtropical regions of Central and South America. Inhabitants of different regions of Brazil employ leaves, fruits and sprouts of Cecropia hololeuca Miq. mainly as anti-inflammatory, anti-asthmatic, expectorant, fever suppressant, and against cough. AIM OF THE STUDY: To evaluate the antinociceptive and anti-inflammatory activities of an aqueous leaf extract of C. hololeuca in a murine model of zymosan-induced arthritis (ZIA) and characterize compounds contributing to these effects. MATERIALS AND METHODS: The crude aqueous extract of C. hololeuca (CAE) was obtained by infusion, screened for antinociceptive and anti-inflammatory activities, and fractionated (solvent partition; RP-2 and Sephadex G-25 column chromatography), yielding fractions that were chemically and pharmacologically investigated. TLC, HPLC-DAD, HPLC-DAD-ESI-MS/MS and NMR analyses were peformed. The antinociceptive activity was assessed by means of acetic acid-induced writhing, hot-plate and rota-rod tests. ZIA was used to evaluate the anti-arthritic activity of oral treatment with CAE, butanolic (BF) and aqueous fraction (AF), as well as the fractions obtained from BF (F2, F2-A and F2-B). Rutin, a flavonoid found in C. hololeuca, was also tested. Mechanical hypernociception, joint edema, local neutrophil recruitment and articular TNF-α quantification were performed to measure the severity of arthritis and identify the anti-inflammatory potential of C. hololeuca. RESULTS: CAE (0.03-1 g/kg, p.o.) showed a dose-related inhibitory effect on acetic acid-induced writhing test, but did not change the pain latency in the hotplate test, nor the first fall time on the rota-rod test. In addition, CAE (1 g/kg, p.o.) inhibited by 65% the mechanical hypernociception, 46% the joint edema, 54% the neutrophil recruitment and 53% the articular TNF-α concentration levels in ZIA. BF (0.4 g/kg, p.o.), AF (0.6 g/kg), F2 (0.1 g/kg) and F2-A (0.045 g/kg), but not F2-B (0.055 g/kg), inhibited the mechanical hypernociception, joint edema and neutrophil recruitment in ZIA. Rutin (0.001-0.03 g/kg, p.o.) produced dose-related inhibitory effects in the mechanical hypernociception, joint edema and neutrophil recruitment, and at 0.03 g/kg also inhibited articular TNF-α synthesis after intra-articular zymosan injection. Isoorientin, isovitexin, rutin and isoquercitrin were identified in the most active fraction (F2-A), along with luteolin and apigenin derivatives, tentatively identified as isoorientin-2″-O-glucoside and isovitexin-2″-O-glucoside. CONCLUSION: This study corroborates the popular use by oral route of aqueous preparations of C. hololeuca against joint inflammatory disorders, such as rheumatoid arthritis. Our results demonstrated for the first time that oral administration of rutin shows antinociceptive and anti-inflammatory effects in ZIA, indicating that this flavonoid is one of the immunomodulatory compounds involved in the anti-arthritic activity of C. hololeuca.

Antinociceptive and antineuropathic effects of cuminaldehyde, the major constituent of Cuminum cyminum seeds: Possible mechanisms of action.

ETHNOPHARMACOLOGICAL RELEVANCE: In Iranian traditional medicine, Cuminum cyminum is a unique medicinal herb for pain relief. Cuminaldehyde has been distinguished as the major constituent of C. cyminum seeds; even though, the analgesic effect of cuminaldehyde has not yet been examined. AIM OF THE STUDY: The nobility of this study was to assess cuminaldehyde effect on nociceptive and neuropathic pains; furthermore, evaluation of its possible mechanisms of action. MATERIALS AND METHODS: Hot plate, formalin, and acetic acid-induced writhing tests were used to evaluate nociception in mice. Naloxone (opioid receptors antagonist), L-arginine (nitric oxide (NO) precursor), L-NAME (NO synthase inhibitor), sodium nitroprusside (NO donor), methylene blue (guanylyl cyclase inhibitor), sildenafil (phosphodiesterase inhibitor), and glibenclamide (KATP channel blocker) were used to determine the implication of opioid receptors and L-arginine/NO/cGMP/KATP channel pathway. Allodynia and hyperalgesia were investigated in the CCI (chronic constriction injury) model of neuropathic pain in rats. The ELISA method was used to measure the inflammatory cytokines in serum samples of rats. The entire chemicals were intraperitoneally injected. RESULTS: Cuminaldehyde (100 and 200 mg/kg) significantly decreased the latency to nociceptive response in the hot plate test. The outcome of cuminaldehyde was completely antagonized by naloxone (2 mg/kg). Formalin- and acetic acid-induced nociception was significantly inhibited by cuminaldehyde (12.5-50 mg/kg). The antinociceptive effect of cuminaldehyde was reversed in writhing test by L-arginine (200 mg/kg), sodium nitroprusside (0.25 mg/kg), and sildenafil (0.5 mg/kg); however, L-NAME (30 mg/kg) and methylene blue (20 mg/kg) enhanced the effect of cuminaldehyde. Glibenclamide (10 mg/kg) did not alter the antinociceptive effects of cuminaldehyde. In the CCI-induced neuropathy, cuminaldehyde (25-100 mg/kg) significantly alleviated allodynia and hyperalgesia and decreased the serum levels of TNF-α and IL-1ß. CONCLUSION: It was attained magnificently that cuminaldehyde exerts antinociceptive and antineuropathic effects through the involvement of opioid receptors, L-arginine/NO/cGMP pathway, and anti-inflammatory function.

Does diet play a role in reducing nociception related to inflammation and chronic pain?

Dietary habits are fundamental issues to assess when modulating health and well-being; however, different nutritional panels may help individuals prevent acute and chronic pain. Many substances, known to be active antioxidants and anti-inflammatory compounds, should serve this fundamental task. Antinociceptive and analgesic natural compounds include flavonoids, terumbone from ginger root, curcuminoids, ω-3 polyunsaturated fatty acids, and taurine. Furthermore, correct intake of trace elements and minerals is strategic to reduce inflammation-related pain. This review addresses these items in an effort to suggest new criteria for proper dietary supplementation to prevent pain.

Repeated Testing With the Hypertonic Saline Assay in Mice for Screening of Analgesic Activity.

BACKGROUND: In vivo animal assays are a cornerstone of preclinical pain research. An optimal stimulus for determining the activity of potential analgesics would produce responses of a consistent magnitude on repeated testing. Intraplantar (i.pl.) injection of hypertonic saline (HS) in mice produces robust nociceptive responses to different analgesics, without evidence of tissue damage. Here, we investigated whether the nociceptive response is changed by repeating the injection at different times and sites in a mouse and whether it is attenuated by morphine. METHODS: We conducted randomized and blinded experiments to assess responses to repeated i.pl. 10% HS in female CD-1 mice. An injection of HS was followed by a second injection into the same hind paw at 4 hours, 24 hours, or 7 days. A separate group of mice each received i.pl. injections at 5, 10, and 15 days. In 2 independent experiments, 30 minutes after initial HS injections in the ipsilateral hind paw, mice received HS injection into the contralateral hind paw or ipsilateral forepaw. The ability of morphine to block the nociceptive responses was examined by injecting morphine at 5-day intervals. RESULTS: Repeated injection of HS did not alter the responses at 4 hours (84 vs 75 seconds; mean difference [95% CI], -9 [-40 to 23]; P = .6), 24 hours (122 vs 113 seconds; -6 [-24 to 12]; P = .5), or 7 days (112 vs 113 seconds; -0.3 [-12 to 11]; P = .95) or at multiple injections (day 0, 122 seconds vs day 5, 121 seconds; -0.3 [-28 to 27], P > .99; day 10, 118 seconds; 2.5 [-36 to 41], P = .99; day 15, 119 seconds; 2 [-36 to 38], P = .99). A previous hind paw injection did not change the responses of the contralateral hind paw (right, 93 seconds versus left, 96 seconds; -3 [-20 to 13], P = .7) or of the ipsilateral forepaw (forepaw after HS, 146 seconds versus forepaw after 0.9% saline, 149 seconds; -3 [-28 to 22], P = .8). Morphine dose-dependently attenuated HS responses (control, 94 seconds vs 4 mg/kg, 66 seconds; 29 [-7 to 64], P = .12; vs 10 mg/kg, 27 seconds; 67 [44-90], P < .0001; 4 vs 10 mg/kg, 67 [44-90], P = .03). CONCLUSIONS: The repetition of i.pl. HS produces consistent reproducible responses without tissue damage. This results in efficient, rapid detection of analgesic activity, reducing the number of animals required.

Ximenia americana heteropolysaccharides ameliorate inflammation and visceral hypernociception in murine caerulein-induced acute pancreatitis: Involvement of CB2 receptors.

BACKGROUND: This study aimed to investigate and characterize the anti-inflammatory and anti-hypernociceptive effects of the total polysaccharides of X. americana (TPL-Xa) bark in a mouse model of acute pancreatitis-induced by caerulein and the potential involvement of cannabinoid receptors. METHODS: TPL-Xa was characterized by1H and 13C NMR spectroscopy. Animals received TPL-Xa (10 mg/kg, i.v.) 30 min before and after caerulein (50 µg/kg, 10×, i.p.) administration. To evaluate the involvement of cannabinoid receptors, AM281 (3 mg/kg, s.c.) and AM630 (1 mg/kg, s.c.) were administered 30 min before TPL-Xa. Plasma levels of amylase and lipase, pancreatic myeloperoxidase (MPO), histology, visceral hypernociception and motor coordination were evaluated 11 and 24 h after acute pancreatitis (AP) induction. RESULTS: TPL-Xa, containing a heteropolysaccharide composed of glucose, galactose, arabinose, rhamnose, fucose and galacturonic acid, reduced amylase and lipase levels, MPO activity, acinar cell necrosis, edema and neutrophil infiltration. TPL-Xa increased the threshold of visceral hypernociception, an effect reversed by AM630, an antagonist of cannabinoid receptor type 2 (CB2). In addition, TPL-Xa did not alter the animals' motor coordination. CONCLUSIONS: TPL-Xa contains heteropolysaccharides that inhibit inflammation and hypernociception in the experimental model of caerulein-induced AP, by a mechanism involving type CB2 receptors.

Antinociceptive and anti-inflammatory activities of a standardizedextract of bis-iridoids from Pterocephalus hookeri.

ETHNOPHARMACOLOGICAL RELEVANCE: Pterocephalus hookeri (C.B. Clarke) Höeck, one of the most popular Tibetan herbs, has been widely applied in Tibetan medicine prescriptions. Chemical investigations have led to the isolation of many bis-iridoids. However, the pharmacological activities of bis-iridoid constituents of this plant have never been reported before. AIM OF THE STUDY: This study evaluated the anti-inflammatory and analgesic activities of afraction of bis-iridoid constituents of P. hookeri (BCPH) in order to provide experimental evidence for its traditional use, such as for cold, flu, and rheumatoid arthritis. MATERIALS AND METHODS: The analgesic effects of BCPH were investigated using the hot-plate test and acetic acid-induced writhing test. The anti-inflammatory activities were observed using the following models: carrageenin-induced edema of the hind paw of rats and xylene-induced ear edema in mice. The effects of dexamethasone administration were also studied. RESULTS: BCPH significantly increased the hot-platepain threshold and reduced acetic acid-induced writhing response in mice. Moreover, BCPH remarkably inhibited xylene-induced ear edema and reduced the carrageenin-induced rat paw edema perimeter. CONCLUSION: The results reveal that BCPH has central, peripheral analgesic activities as well as anti-inflammatory effects, supporting the traditional application of this herb in treating various diseases associated with inflammation and pain.

Eugenia brasiliensis leaves extract attenuates visceral and somatic inflammatory pain in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Eugenia brasiliensis Lam. (Myrtaceae) is a Brazilian tree distributed throughout Atlantic rain forest, since Bahia until Santa Catarina state, and is popularly known as "grumixaba, grumixameira, cumbixaba, ibaporoiti, and cereja-brasileira". The bark and leaves of Eugenia brasiliensis are used in folk medicine as adstringent, diuretic, energizing, anti-rheumatic and anti-inflammatory. This study aimed at investigating the chemical composition, antinociceptive and anti-inflammatory effect of the hydroalcoholic extract of Eugenia brasiliensis (HEEb). MATERIAL AND METHODS: Chemical composition of the HEEb was determined by High Performance Liquid Chromatography/ESI-Mass Spectrometry (HPLC-ESI-MS/MS). The antinociceptive and anti-inflammatory effects of HEEb (30-300 mg/kg) was verified in mice after oral administration by intra-gastric gavage (i.g.) 60 min prior to experimentation. It was investigated whether HEEb decreases visceral pain and leukocyte migration induced by an intraperitoneal (i.p.) injection of acetic acid (0.6%). We also evaluated whether HEEb decreases nociceptive behavior induced by formalin (including paw edema and temperature), prostaglandin E2 (PGE2), histamine, and compound 48/80. Finally, we evaluated the effect of HEEb in the chronic inflammatory (mechanical and thermal hypersensitivity) pain induced by complete Freund's adjuvant (CFA), as well as quantifying the concentration of the pro-inflammatory cytokines TNF-α and IL-6 in the paw by ELISA method. RESULTS: Seven polyphenols were identified in HEEb by HPLC-ESI-MS/MS analysis. HEEb treatment alleviated nocifensive behavior and leukocyte migration caused by acetic acid. Moreover, HEEb also reduced the inflammatory pain and paw temperature induced by formalin, as well as it decreased nociceptive behavior induced by histamine and compound 48/80. Finally, acute and repeated treatment of animals with HEEb (100 mg/kg, i.g.) markedly reduced the mechanical and thermal (heat) hypersensitivity, besides decrease paw edema and temperature induced by CFA, and this effect was evident until the day 7. Moreover, repeated treatment with HEEb (100 mg/kg, i.g.) significantly reduced the levels of IL-6 and TNF-α in the paw when compared to the CFA group. CONCLUSIONS: This is the first report showing that HEEb presents antinociceptive and anti-inflammatory effects in the visceral and somatic inflammatory pain in mice, possibly involving the inhibition of histamine receptors and pro-inflammatory cytokines activated pathways. Our results are of interest because they support the use of Eugenia brasiliensis as a potential source of phytomedicine for inflammatory diseases and pain.

Anti-nociceptive effect of methanol extract of leaves of Senna singueana in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Senna singueana (Del.) Lock (Fabaceae) is a shrub or tree found in Ethiopia and other African countries. It has been traditionally used for different conditions including treatment of pain conditions in humans and animals. Although various reports are available in the literature claiming different activities of the plant, scientific studies supporting analgesic potential of S. singueana are lacking and the present study aimed to investigate the antinociceptive effect of methanol extract of leaves of S. singueana in mice. MATERIALS AND METHODS: Anti-nociceptive activity of S. singueana (200 mg/kg and 400 mg/kg, p.o) was investigated using acetic acid-induced writhing, formalin-induced paw licking, and hot plate tests. Acute oral toxicity was determined using a slightly modified guideline (423) of the Organization for Economic Cooperation and Development. RESULTS: S. singueana extract increased the percentage of inhibition of writhing response and licking response (neurogenic and inflammatory phase) in acetic acid-induced writhing and formalin-induced paw licking tests, respectively. It also significantly (p ≤ 0.05) increased the percentage of mean maximal effect (%MPE) compared to control group in the hot-plate test. In all models, the combination of S. singueana with either diclofenac or morphine produced statistically significant increase (p ≤ 0.05) in the percentage of inhibition of writhing, paw licking, and %MPE compared to single treatment groups. It was also found that the 400 mg/kg extract produced higher antinociceptive effects (p ≤ 0.05) compared to the 200 mg/kg. CONCLUSION: S. singueana leaves may have analgesic effect that is mediated through both peripheral and central mechanisms and could be used as adjuvant treatment to the modern analgesics.

Herb-drug interaction of Andrographis paniculata (Nees) extract and andrographolide on pharmacokinetic and pharmacodynamic of naproxen in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Andrographis paniculata Nees (Acanthacae) have broad range of pharmacological effects such as hepatoprotective, antifertility, antimalarial, antidiabetic, suppression of various cancer cells and anti-inflammatory properties and is widely used medicinal plant in the traditional Unani and Ayurvedic medicinal systems. Andrographolide (AN) is one of the active constituent of the A. paniculata Nees extract (APE). They have been found in many traditional herbal formulations in India and proven to be effective as anti-inflammatory drug. AIM OF THE STUDY: To evaluate the pharmacokinetic and pharmacodynamic (anti arthritic) herb-drug interactions of A. paniculata Nees extract (APE) and pure andrographolide (AN) with naproxen (NP) after oral co-administration in wistar rats. MATERIALS AND METHODS: After oral co-administration of APE (200mg/Kg) and AN (60mg/kg) with NP (7.5mg/kg) in rats, drug concentrations in plasma were determined using HPLC method. The main pharmacokinetic parameters of Cmax, tmax, t1/2, MRT, Vd, CL, and AUC were calculated by non-compartment model. Change in paw volume, mechanical nociceptive threshold, mechanical hyperalgesia, histopathology and hematological parameters were evaluated to study antiarthritic activity. RESULTS: Co-administration of NP with APE and pure AN decreased systemic exposure level of NP in vivo. The Cmax, tmax, AUC0-t of NP was decreased. In pharmacodynamic study, NP (10mg/kg) alone and NP+AN (10+60mg/kg) groups exhibited significant synergistic anti-arthritic activity as compared to groups NP+APE, APE and AN alone. CONCLUSION: The results obtained from this study suggested that NP, APE and pure AN existed pharmacokinetic herb-drug interactions in rat which is correlated with anti-arthritic study. The knowledge regarding possible herb-drug interaction of NP might be helpful for physicians as well as patients using AP. So further studies should be done to understand the effect of other herbal ingredients of APE on NP as well as to predict the herb-drug interaction in humans.

Antinociceptive activity and mechanism of action of hydroalcoholic extract and dichloromethane fraction of Amphilophium crucigerum seeds in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: The medicinal plant generally known as monkey's comb (Amphilophium crucigerum) has been popularly described for the treatment of neuropathic and inflammatory pain, specially seeds preparations. AIM OF THE STUDY: The goal of the present study was to evaluate the antinociceptive effect of the crude extract (Crd) and dichloromethane fraction (Dcm) of A. crucigerum seeds, and investigate the involvement of transient receptor potential vanilloid 1 (TRPV1) receptor in this effect. MATERIALS AND METHODS: Male Swiss mice were used in this study. The effects of Crd and Dcm was tested on capsaicin-induced Ca2+ influx or the specific binding of [3H]-resiniferatoxin. Moreover, after treatment with Crd or Dcm, animals were exposed to acute pain (hot water tail-flick and capsaicin intraplantar test) or chronic pain models (injection of complete Freund's adjuvant or partial ligation of the sciatic nerve). Acute adverse effects were also noted: locomotor activity, corporal temperature, hepatic or renal damage, gastrointestinal transit alteration, and ulcerogenic activity. RESULTS: The oral administration of Crd or Dcm resulted in an antinociceptive effect in the hot water tail-flick (48°C) and capsaicin intraplantar tests. Furthermore, these preparations exhibited antinociceptive and anti-inflammatory effects in a chronic inflammatory pain model, and antinociceptive effects in a neuropathic pain model. Moreover, Crd and Dcm reduced capsaicin-induced Ca2+ influx and diminished the [3H]-resiniferatoxin specific binding to spinal cord membranes. Acute adverse events were not found with Crd or Dcm administration. CONCLUSION: In conclusion, our results support the analgesic effect of A. crucigerum and suggest the presence of compounds that may act as TRPV1 antagonists.

Resveratrol-induced antinociception is involved in calcium channels and calcium/caffeine-sensitive pools.

Resveratrol has been widely investigated for its potential health properties, although little is known about its mechanism in vivo. Previous studies have indicated that resveratrol produces antinociceptive effects in mice. Calcium channels and calcium/caffeine-sensitive pools are reported to be associated with analgesic effect. The present study was to explore the involvement of Ca2+ channel and calcium/caffeine-sensitive pools in the antinociceptive response of resveratrol. Tail-flick test was used to assess antinociception in mice treated with resveratrol or the combinations of resveratrol with MK 801, nimodipine, CaCl2, ryanodine and ethylene glycol tetraacetic acid (EGTA), respectively. The Ca2+/calmodulin-dependent protein kinase II (CaMKII) and brain-derived neurotrophic factor (BDNF) levels in the spinal cord were also investigated when treated with the above drugs. The results showed that resveratrol increased the tail flick latency in the tail-flick test, in dose-dependent manner. N-methyl-D-aspartate (NMDA) glutamate receptor antagonist MK 801 potentiated the antinociceptive effects of sub-threshold dose of resveratrol at 10 mg/kg. Ca2+ channel blocker, however, abolished the antinociceptive effects of resveratrol. In contrast to these results, EGTA or ryanodine treatment (i.c.v.) potentiated resveratrol-induced antinociception. There was a significant decrease in p-CaMKII and an increase in BDNF expression in the spinal cord when combined with MK 801, nimodipine, ryanodine and EGTA. While an increase in p-CaMKII level and a decrease in BDNF expression were observed when high dose of resveratrol combined with CaCl2. These findings suggest that resveratrol exhibits the antinociceptive effects by inhibition of calcium channels and calcium/caffeine-sensitive pools.

In vivo antinociceptive and muscle relaxant activity of leaf and bark of Buddleja asiatica L.

The current study was designed to assess the antinociceptive and skeleton muscle relaxant effect of leaves and barks of Buddleja asiatica in animal models. In acetic acid induced writhing test, pretreatment of ethanolic extract of leaves and barks evoked marked dose dependent antinociceptive effect with maximum of 70% and 67% pain relief at 300mg/kg i.p. respectively. In chimney test, the ethanolic extract of leaves and barks evoked maximum of 66.66% and 53.33% muscle relaxant effect after 90min of treatment at 300mg/kg i.p respectively. In traction test, the ethanolic extract of leaves and barks caused maximum of 60% and 73.33% muscle relaxant effect after 90min of treatment at 300mg/kg i.p respectively. In short, both leaves and barks demonstrated profound antinociceptive and skeleton muscle relaxant effects and thus the study provided natural healing agents for the treatment of said disorders.

Evidence of anti-inflammatory and antinociceptive activities of Plinia edulis leaf infusion.

ETHNOPHARMACOLOGICAL RELEVANCE: Plinia edulis (Vell.) Sobral (Myrtaceae) is native and endemic to the Brazilian Atlantic Rainforest. Popularly known as "cambucá", it has been used in folk medicine for the treatment of stomach disorders, diabetes, bronchitis, inflammation and as tonic. Although there are numerous records concerning its popular use as analgesic and anti-inflammatory, scientific information regarding these pharmacological activities is limited. Therefore, the aim of this study was to characterize the anti-inflammatory and antinociceptive activity of P. edulis leaf infusion (AEPe) in mice. MATERIALS AND METHODS: The acetic acid-induced writhing response and mechanical nociceptive paw tests were used to evaluate the antinociceptive activity. Carrageenan-induced paw edema and lipopolysaccharide-induced peritonitis were used to investigate the anti-inflammatory activity. The substances in AEPe were identified by HPLC-MS analysis. RESULTS: At the test doses 30-300mg/kg p.o., AEPe has clearly exhibited anti-inflammatory effects, reducing carrageenan-induced paw edema and inhibiting leukocyte recruitment into the peritoneal cavity. The infusion has shown significant antinociceptive activity in both models of nociception. Gallic acid, myricitrin, guaijaverin, quercitrin, quercetin, corosolic acid, maslinic acid, oleanolic acid and ursolic acid were identified in AEPe. CONCLUSION: P. edulis infusion presented antinociceptive and anti-inflammatory activities in all experiments realized in this study, which could be related to the presence of triterpenoids and flavonoids. These results provide scientific support for the traditional use of this species in the management of pain and inflammation.