Formalin-induced Paw Licking Test Research Articles

Antinociceptive and antineuropathic effects of Trifolium resupinatum L. on formalin-induced nociception and cervical spinal cord hemi-contusion: Underlying Mechanisms

Ethnopharmacological relevanceTrifolium resupinatum L. (Fabaceae), known as Persian clover, ethnomedicinally used in Persian folk medicine to treat peritoneal inflammation, rheumatism, and back pain. Aim of the studyTo investigate the antineuropathic and antinociceptive activities of Trifolium resupinatum leaves essential oil (TREO) in male Wistar rats, as well as to explore the potential mechanisms of action. Materials and methodsThe antinociceptive activity of TREO and its main constituents, quercetin (Qc) was assessed using the formalin-induced paw licking test. Moreover, the potential mechanisms of antinociception were evaluated through various competitive and non-competitive antagonisms. Additionally, the antineuropathic potential was investigated using the cervical spinal cord hemi-contusion (CCS) model, and the role of phosphorylated Stat-3 was analyzed using Western blotting. ResultsTREO exerted significant antinociceptive activity (P < 0.01) in both phases of the formalin-induced test; however, its effects were more pronounced in the second phase. Modulators of the NO-cGMP-K+ channel pathway significantly reversed the antinociceptive activity of TREO (P < 0.05). Additionally, antagonists of TRPV1 and TRPV2, as well as CB1 and GABAA receptors, significantly reversed the antinociceptive effects of TREO (P < 0.05). In another study, both TREO and Qc significantly attenuated hyperalgesia and mechanical allodynia (P < 0.01) when evaluated using the CCS-induced nociception model. Notably, TREO also reduced the expression levels of interleukin-1 beta, interleukin-2, and tumor necrosis factor alpha in CCS-induced rats (P < 0.05). ConclusionTREO and Qc exhibit both antinociceptive and anti-neuropathic activities. The antinociceptive effects are partially mediated through the NO-cGMP-K+ channel pathways, along with the activation of TRPV, GABA, and cannabinoid receptors. Furthermore, the anti-neuropathic activity of TREO may be partially regulated through the inhibition of cytokines.

Exploring the antinociceptive potential of homoeriodictyol in nociception models

Context: Homoeriodictyol is a flavonoid with known antioxidant, anti-inflammatory, and anti-tumor properties found in various plants. However, its potential analgesic effects have not been explored. Aims: To investigate the pain-relieving properties of homoeriodictyol using different mouse models of nociception. Methods: Various doses of homoeriodictyol (50, 100, 150, and 200 µg/kg) were administered to mice and evaluated using the acetic acid-induced writhing test, the hot plate test, and the formalin-induced paw licking assay. These effects were compared with those of mice treated with acetylsalicylic acid or morphine, both with and without naloxone, an opioid receptor antagonist. Additionally, capsaicin- and glutamate-induced paw-licking tests were conducted to assess the involvement of the vanilloid and glutamatergic systems, respectively. Results: Homoeriodictyol demonstrated a significant and dose-dependent reduction in nociceptive behavior in the acetic acid-induced writhing test, achieving a 52.4% inhibition at a dose of 200 µg/kg. It also substantially increased the latency period in response to the hot plate test (65.8% at 200 µg/kg) and significantly suppressed both the neurogenic and inflammatory phases in the formalin-induced paw-licking test. Notably, the effects of homoeriodictyol in the hot plate test and formalin-induced paw-licking test were significantly reversed by naloxone. Furthermore, homoeriodictyol effectively reduced neurogenic nociception induced by intraplantar injections of glutamate and capsaicin (57.8% and 76.9%, respectively, at a dose of 200 µg/kg). Conclusions: This study concludes that homoeriodictyol exhibits antinociceptive activity in mice, acting through both central and peripheral pathways.

Polyphenol-rich Sorghum bicolor supplement exhibits anti-nociceptive activity and protective effects against pathological changes associated with complete Freund's adjuvant induced arthritis in rodents

IntroductionArthritis is a common inflammatory joint disease; causing severe pain, anxiety, and depression. Sorghum bicolor L. Moench (Pocaeae) is used for treating cough, asthma, and arthritic pain in Traditional Chinese Medicine (TCM). This study evaluates the anti-nociceptive and anti-arthritic effects of the polyphenol-rich Sorghum bicolor supplement (SBS) in rodents. MethodsThe anti-nociceptive activity of SBS was assessed using hot plate, acetic acid mouse writhing, and formalin-induced paw licking tests in mice. In the arthritis study, rats received SBS (50, 100, and 200 mg/kg p.o) for 28 days. Thirty minutes after treatment on days, 1 and 20, rats received intra-articular injection of Complete Freund's adjuvant (CFA) for arthritis induction. Arthritic scores and paw edema were determined before assessing motor function, anxiety, depression, hyperalgesia and allodynia on day 28. Lipid profiles were determined, and ankle and brain tissues were analyzed for oxidative stress and inflammatory biomarkers, alongside histopathological studies. ResultsSBS reduced nociceptive responses induced by noxious heat, acetic acid and formalin in mice. In CFA-injected rats, SBS decreased paw volume and arthritic scores, and increased pain thresholds to thermal, cold, and mechanical stimuli. The SBS reduced motor activity, anxiety and depression, and improved serum lipid profiles in arthritic rats. It further modulated oxidative stress, pro-inflammatory cytokines, nuclear factor kappa (NF-kB), apoptotic markers, nuclear factor erythroid 2-related factor 2 (NRF2), glutamic acid decarboxylase (GAD) and brain-derived neurotrophic factor (BDNF) in CFA-treated rats. SBS produced histopathological improvements in joint tissues of arthritic rats. DiscussionThis study revealed that SBS exhibited anti-nociceptive activity in mice and reduces inflammation, hyperalgesia, anxiety and depression in CFA-arthritic rats. The ability of SBS to modulate key biomarkers such as pro-inflammatory cytokines, NF-κB, caspases, Nrf2, BDNF, and GAD highlights its multifaceted approach in addressing both the physical and psychological aspects of arthritis, providing a comprehensive therapeutic strategy, justifying its use in TCM for this debilitating condition.

Evaluation of Anticancer, Anthelminthic, Anti-Nociceptive, Antidiabetic and Toxicological Investigation of Ludwigia adscendens

The present research investigated Ludwigia adscendens crude methanol extract invitro anticancer anthelminthic, and invivo anti-nociceptive, antidiabetic and toxicological properties. The coarsely dried plant powder was extracted using methanol. The methanolic extract (MELA) was further tested for anticancer, anthelminthic, anti-nociceptive, antidiabetic and toxicological activities. Cell Viability Assay was used for anticancer testing, and the earthworm assay was used for anthelminthic testing using different concentrations. Antinociceptive tests were done on Swiss albino mice at 200 and 400 mg/kg utilizing a hot plate, acetic acid induced writhing &amp; formalin-induced paw licking tests. Antidiabetic test was done using Blood Glucose Determination test using the dose of 150 mg/kg and 300 mg/kg. Acute toxicity was tested utilizing cinnamon oil-induced toxicological tests at 3000, 5000 and 7000 mg/kg. The MELA demonstrated 39.16% inhibition at 1000µg/mL in the Cell Viability Assay. The earthworm died after 6 minutes and 4 seconds in the 100 mg/mL anthelminthic test, whereas Albendazole killed it in 4 minutes and 20 seconds. Hot plate test results were substantial. The formalin-induced nociception test demonstrated strong inhibition rates of 79.54% in the early phase and 74.54% in the late phase at 400 mg/kg, compared to 62.99% and 68.18% for diclofenac sodium. Acetic acid-induced writhing test showed 77.66% of pain inhibition where’s Diclofenac sodium showed 79.61%. MELA inhibited blood glucose level very significantly compared to the standard Glibenclamide. In toxicological testing, 7000 mg/kg killed mice 2/5, whereas cinnamon oil killed 5/5 within 24 hours. The study shows that MELA has moderate anticancer, significant anthelmintic, anti-nociceptive, antidiabetic and mild toxicological properties. They may support the plant's use in conventional medicine to relieve pain, minimize drug intoxication, and prevent cancer, control diabetes and parasitic disorders.

Synthesis, molecular docking evaluation for LOX and COX-2 inhibition and determination of in-vivo analgesic potentials of aurone derivatives

In the current study, seven (7) aurone derivatives (ADs) were synthesized and employed to in-vitro LOX and COX-2 assays, in-vivo models of acetic acid-induced mice writhing, formalin-induced mice paw licking and tail immersion test to evaluate their analgesic potential at the doses of 10 mg and 20 mg/kg body weight. Molecular docking was performed to know the active binding site at both LOX and COX-2 as compared to standard drugs. Among the ADs, 2-(3,4-dimethoxybenzylidene)benzofuran-3(2H)-one (WE-4)possessed optimal LOX and COX-2 inhibitory strength (IC50=0.30 μM and 0.22 μM) as compared to standard (ZileutonIC50 = 0.08 μM, CelecoxibIC50 = 0.05 μM). Similarly in various pain models compound WE-4 showed significantly (p < 0.05) highest percent analgesic potency as compared to control at a dose of 20 mg/kg i.e. 77.60 % analgesic effect in acetic acid model, 49.97 % (in Phase-1) and 70.93 % (inPhase-2) analgesic effect in formalin pain model and 74.71 % analgesic response in tail immersion model. By the administration of Naloxone, the tail flicking latencies were reversed (antagonized) in all treatments. The WE-4 (at 10 mg/kg and 20 mg/kg) was antagonized after 90 min from 11.23 ± 0.93 and 13.41 ± 1.21 to 5.30 ± 0.48 and 4.80 ± 0.61 respectively as compared to standard Tramadol (from 17.74 ± 1.33 to 3.70 ± 0.48), showing the opiodergic receptor involvement. The molecular docking study of ADs revealed that WE-4 had a higher affinity for LOX and COX-2 with docking scores of -4.324 and -5.843 respectively. As a whole, among the tested ADs, compound WE-4 demonstrated excellent analgesic effects that may have been caused by inhibiting the LOX and COX-2 pathways.

Exploring the phytochemical, antioxidant, antimicrobial and analgesic potentials of Solanum erianthum as an alternative biological feedstock for producing sustainable biochemicals

Solanum erianthum is a medicinal herb that offers health benefits and valuable phytochemicals in treating human ailments. Phytochemicals and therapeutic properties of different parts of S. erianthum in four solvents: water, petroleum ether, chloroform, and methanol were evaluated. Stem showed high alkaloids (15.40 ± 0.7%) and tannins (8.6 ± 0.3%), followed by higher root saponins (12.2 ± 0.2%). In contrast, leaf exhibited high flavonoid (13.5 ± 0.5%) and phenolic (12.30 ± 1.0%) contents. The petroleum ether extract of the stem had the highest 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity (70.66 ± 0.3%) and ferric reducing antioxidant power (FRAP) activity (70.55 ± 0.08 μg/mL). In contrast, the petroleum ether extract of the root had maximum total antioxidant capacity (TAC) (1.065 ± 0.6 absorbance at 695 nm), while the fruit aqueous extract showed highest activity in ferric thiocyanate assay (FTC) (61.53 ± 0.1). Antibacterial activity ranged from 19 to 51 mm, while antifungal was from 11 to 43 mm. The methanol extracts of the root and leaf showed the highest antimicrobial activity against the tested bacteria and fungi. The methanol extract of fruit showed the highest analgesic activity (11.98 ± 2.14 s) and writhing inhibition (1st phase 85.1% and 2nd phase 96.7%), as confirmed by the formalin-induced paw licking test. Fruit extract showed active central and peripheral analgesic effects in early (88.9%) and late (92.8%) phases of pain, comparable to paracetamol (60 mg/kg). In conclusion, this study demonstrates the antioxidant, antimicrobial, and antifungal properties as well as central and peripheral analgesic effects of S. erianthum extracts.

Analgesic and anti-inflammatory effects of galangin: a potential pathway to inhibit transient receptor potential vanilloid 1 receptor activation.

Galangin, commonly employed in traditional Chinese medicine for its diverse medicinal properties, exhibits potential in treating inflammatory pain. Nevertheless, its mechanism of action remains unclear. Mice were randomly divided into 4 groups for 7 days: a normal control group, a galangin-treated (25 and 50 mg/kg), and a positive control celecoxib (20 mg/kg). Analgesic and anti-inflammatory effects were evaluated using a hot plate test, acetic acid-induced writhing test, acetic acid-induced vascular permeability test, formalininduced paw licking test, and carrageenan-induced paw swelling test. The interplay between galangin, transient receptor potential vanilloid 1 (TRPV1), NF-κB, COX-2, and TNF-α proteins was evaluated via molecular docking. COX- 2, PGE2, IL-1β, IL-6, and TNF-α levels in serum were measured using ELISA after capsaicin administration (200 nmol/L). TRPV1 expression in the dorsal root ganglion was analyzed by Western blot. The quantities of substance P (SP) and calcitonin gene-related peptide (CGRP) were assessed using qPCR. Galangin reduced hot plate-induced licking latency, acetic acid-induced contortions, carrageenantriggered foot inflammation, and capillary permeability in mice. It exhibited favorable affinity towards TRPV1, NF- κB, COX-2, and TNF-α, resulting in decreased levels of COX-2, PGE2, IL-1β, IL-6, and TNF-α in serum following capsaicin stimulation. Galangin effectively suppressed the upregulation of TRPV1 protein and associated receptor neuropeptides CGRP and SP mRNA, while concurrently inhibiting the expression of NF-κB, TNF-α, COX-2, and PGE2 mRNA. Galangin exerts its anti-inflammatory pain effects by inhibiting TRPV1 activation and regulating COX-2, NF-κB/TNF-α expression, providing evidence for the use of galangin in the management of inflammatory pain.

Evaluation of the antinociceptive activities of natural propolis extract derived from stingless bee Trigona thoracica in mice.

: Stingless bee propolis is a popular traditional folk medicine and has been employed since ancient times. This study aimed to evaluate the antinociceptive activities of the chemical constituents of aqueous propolis extract (APE) collected by Trigona thoracica in a nociceptive model in mice. : The identification of chemical constituents of APE was performed using high-performance liquid chromatography (HPLC). Ninety-six male Swiss mice were administered APE (400 mg/kg, 1,000 mg/kg, and 2,000 mg/kg) before developing nociceptive pain models. Then, the antinociceptive properties of each APE dose were evaluated in acetic acid-induced abdominal constriction, hot plate test, and formalin-induced paw licking test. Administration of normal saline, acetylsalicylic acid (ASA, 100 mg/kg, orally), and morphine (5 mg/kg, intraperitoneally) were used for the experiments. : HPLC revealed that the APE from Trigona thoracica contained p-coumaric acid (R2 = 0.999) and caffeic acid (R2 = 0.998). Although all APE dosages showed inhibition of acetic acid-induced abdominal constriction, only 2,000 mg/kg was comparable to the result of ASA (68.7% vs. 73.3%, respectively). In the hot plate test, only 2,000 mg/kg of APE increased the latency time significantly compared to the control. In the formalin test, the durations of paw licking were significantly reduced at early and late phases in all APE groups with a decrease from 45.1% to 53.3%. : APE from Trigona thoracica, containing p-coumaric acid and caffeic acid, exhibited antinociceptive effects, which supports its potential use in targeting the prevention or reversal of central and peripheral sensitization that may produce clinical pain conditions.

The oral administration of Lotus corniculatus L. attenuates acute and chronic pain models in male rats

Ethnopharmacological relevanceLotus corniculatus L. (Fabaceae) traditionally used in Persian folk medicine to heal peritoneal inflammation and back pain. Aim of the studyTo explore the antinociceptive (acute pain) and anti-neuropathic (chronic pain) activities of Lotus corniculatus leaves essential oil (LCEO) in addition to uncovering the possible mechanisms of antinociception. Materials and methodsLCEO as well as the pure oleanolic acid (OA) compound, were assayed for their effects on acute (formalin induced paw licking test or FIPT) and chronic (cervical contusion injury models on the fifth cervical vertebra or CCS; 14-day intervals) pain. The possible involvements of NO-cGMP-K+ channel, TRPV, dopamine, cannabinoid, PPAR, adrenergic, and opioid mechanisms in the antinociceptive activity of LCEO have studied by formalin test. The levels of p53 and inflammatory markers were measured using a streptavidin biotin immune peroxidase complex and ELISA methods, respectively. ResultsThe LCEO and OA exerted antinociceptive activity in the first-phase of FIPT. Pretreatment with antagonists of TRPV1, dopamine D2, cannabinoid type1 and 2, and NO-cGMP-K+ channel blockers (glibenclamide, L-NAME and methylene blue) attenuated the antinociceptive effect of LCEO in FIPT. In addition, LCEO and OA meaningfully reduced hyperalgesia (days 6–14) and mechanical allodynia (days 2–14) in the CCS model. LCEO suppressed the apoptotic marker (p53) in CCS model and also ameliorated IL-2, TNF-α, and IL-1 in the spinal cord. ConclusionFinally, LCEO inhibited acute (possibly via the modulation of opioid, TRPV, dopamine, cannabinoid mechanisms as well as NO-cGMP-K+ channel) and chronic pain (via suppressing apoptotic and inflammatory markers) in male rats. The results also suggest that OA has analgesic activity against acute and chronic pain conditions.

Analgesic Activity of Methanolic Extract of Litsea deccanensis Gamble Bark in Mice Model

Litsea deccanensis Gamble. (Family: Lauraceae) is used traditionally for sprained or swollen joints such as ankles or knee. Still, there is no report for its analgesic activity, therefore the present study was aimed to evaluate analgesic activity of the crude methanolic extract of L. deccanensis (MELD) bark in various mice models. Acetic acid-induced writhing, Eddy’s hot plate and formalin induced paw licking tests were performed to evaluate the pain reducing/relieving effects. In acetic acid-induced writhing model, MELD showed significant reduction of squirming (p &lt; 0.001, p &lt; 0.01 and p &lt; 0.05) in a dose dependent manner as compared to control. In the heat induced pain model (Eddy’s hot plate method), MELD showed a slight increment of the latency time for the initiation of the reaction in the experimental animals, that revealed a moderate analgesic activity of MELD when compared to control group, but the results were insignificant. Whereas, in the formalin induced pain model, the reaction time was decreased significantly (p &lt; 0.05) with the increment of doses for the studied plant extract (MELD) as well as standard in the late phase (20-30 min) of the study. So, the present study concluded a significant reduction of acetic acid-induced squirming or writhing, and formalin induced biting or licking in mice, provided us the evidence of having pain reducing potential. Bangladesh Pharmaceutical Journal 26(2): 144-149, 2023 (July)

2ʹ,3,3,5ʹ-Tetramethyl-4ʹ-nitro-2ʹH-1,3ʹ-bipyrazole exerts antinociceptive effect using various nociception models

Background: 2ʹ,3,3,5ʹ-Tetramethyl-4ʹ-nitro-2ʹH-1,3ʹ-bipyrazole (TMNB) is a novel bipyrazole compound that exhibited antidiabetic and anti-inflammatory properties. However, its analgesic effect has not been investigated. This study aimed to assess the antinociceptive activity of TMNB using different nociception mouse models. Methods: TMNB doses (50, 100, 150, and 200 µg/kg) were assessed in mice using the acetic acid-induced writhing test, hot plate test, and formalin-induced paw licking assay. The effects were compared to those of mice treated with acetylsalicylic acid or morphine in the presence or absence of naloxone. Capsaicin- and glutamate-induced paw-licking tests were also used to evaluate the involvement of the vanilloid and glutamatergic systems, respectively. Results: TMNB produced significant dose-dependent inhibition of nociceptive behavior in the acetic acid-induced writhing test, showing 66% inhibition at a dose of 200 µg/kg. TMNB also caused a significant increase in the latency period in response to the hot plate test (68.2% at 200 µg/kg), and significantly inhibited both the neurogenic and inflammatory phases in the formalin-induced paw-licking test. Naloxone significantly reverses the effect of TMNB in both the hot plate test and formalin-induced paw-licking test. Moreover, TMNB significantly inhibited the neurogenic nociception induced by intraplantar injections of glutamate and capsaicin (53% and 77.1%, respectively at a dose of 200 µg/kg). Conclusion: TMNB possesses antinociceptive activity in mice that is mediated through both central and peripheral pathways.

Lysionotin exerts antinociceptive effects in various models of nociception induction

BackgroundLysionotin, a natural flavonoid extracted from Lysionotus pauciflorus Maxim (Gesneriaceae), has several pharmacological effects including anti-bacterial, anti-hypertensive and anti-inflammatory effects. However, its analgesic effect has not been investigated. This study aimed to assess the antinociceptive activity of lysionotin using chemically and thermally induced nociception in a mouse model. MethodsThe antinociceptive effects of various lysionotin doses (50, 100, 150, and 200 μg/kg) were assessed in mice using the acetic acid-induced writhing test, hot plate test, and formalin-induced paw licking assay. The effects were compared to those of mice treated with acetylsalicylic acid or morphine in the presence or absence of naloxone (an opioid receptor antagonist). Capsaicin- and glutamate-induced paw licking tests were also used to evaluate the involvement of the vanilloid and glutamatergic systems, respectively. ResultsLysionotin produced significant dose-dependent inhibition of nociceptive behavior in the acetic acid-induced writhing test, showing 60% inhibition at a dose of 200 μg/kg. Lysionotin also caused a significant increase in the latency period in response to the hot plate test (76.4% at 200 μg/kg), and significantly inhibited both the neurogenic and inflammatory phases in the formalin-induced paw licking test. Naloxone significantly reverses the effect of lysionotin in both hot plate test and formalin-induced paw licking test. Moreover, lysionotin significantly inhibited the neurogenic nociception induced by intraplantar injections of glutamate and capsaicin (57% and 67.2%, respectively at a dose of 200 μg/kg). Thus, lysionotin exhibited peripheral and central antinociception through the modulation of vanilloid receptors, opioid receptors, and the glutamatergic system. ConclusionLysionotin possesses antinociceptive activity on adult mice that is mediated through both central and peripheral pathways.

Anti-Inflammatory and Antimicrobial Effects of Eucalyptus spp. Essential Oils: A Potential Valuable Use for an Industry Byproduct.

In Brazil, the use of Eucalyptus is focused on the production of wood or pulp for the paper industry but without any general recovery of waste, with leaves and branches being left on the ground. One possibility is to use these residues as raw materials in the production of industrially relevant and value-added compounds such as essential oil. The aim of the present study was to investigate the chemical composition, yield, anti-inflammatory/antinociceptive activities, and acute toxicity in mice, as well as the antimicrobial effects of essential oils from the leaves of 7 varieties of Eucalyptus and hybrids against Escherichia coli, Staphylococcus aureus, and Candida albicans. The extraction of oils was carried out using hydrodistillation, and they were analyzed by gas chromatography coupled to mass spectrometry. Urocam and Grancam were the plants that obtained the highest oil yield, with yields of 3.32 and 2.30%, respectively. The main chemical components identified in these plants were 1.8 cineole and α-pinene. The antinociceptive effect of the 7 oils (50 mg/kg, p.o.) was initially assessed in the acetic acid-induced writhing test. In this assay, a significant (p < 0.05) antinociceptive/anti-inflammatory effect was observed from 4 tested essential oils (E. benthamii, E. saligna, and the hybrids Urocam and Grancam) when compared to the vehicle-treated group. This effect was then confirmed in the formalin-induced paw licking test. No toxicological effects or alterations were observed in motor coordination after the administration of the studied oils to the animals. In the antimicrobial evaluation, the seven essential oils inhibited the growth of S. aureus, E. coli, and C. albicans at different concentrations. Collectively, these results demonstrate that the essential oil from the leaves and branches of Eucalyptus species and varieties present potential biomedical applications and represent a source of antimicrobial and/or anti-inflammatory compounds.

Phytochemical Screening and Pharmacological Evaluation of the Methanolic Extract of Cissus Elongata Roxb. Leaves

This study evaluates the pharmacological activity of the methanolic extract of Cissus elongata Roxb. leaves. Dried leaves of C. elongata were extracted with methanol. The crude extract was then tested to identify the presence of different phytoconstituents. To evaluate the pharmacological effects of this plant- analgesic, anti-diarrheal, anti-inflammatory and antipyretic, tests were conducted using animal models. Analgesic activity was evaluated by an acetic acid-induced writhing test, formalin-induced paw-licking test paw-licking immersion test. Castor oil-induced anti-diarrheal test was performed to evaluate anti-diarrheal activity. Xylene-induced ear edema and brewer’s yeast-induced pyrexia test were performed to investigate anti-inflammatory and antipyretic activity respectively. Phytochemical screening revealed the presence of carbohydrates, tannins, fat, and fixed oil. In writhing test, the extract showed 45.68±3.99 % and 52.28±1.67 % inhibition of writhing at a dose of 200 mg/kg and 400 mg/kg respectively whereas it was 73.09±1.01 % for the standard drug compared to the control group. In the formalin-induced paw-licking test, the percentage inhibition of licking by both doses of the extract was more in the delayed phase than in the acute phase. In the tail immersion test, 200 mg/kg dose didn’t show a significant effect but 40 0mg/kg showed significant (*P&lt;0.05 vs. control) analgesic activity at 30 min, 60 min and 120 min time periods. In an anti-diarrheal study, 400 mg/kg dose showed (68.42±0.87 % inhibition of diarrhea) almost similar anti-diarrheal effect as the standard drug loperamide HCl (71.05±0.58 %). In xylene induced ear edema test, both doses of the extract showed little anti-inflammatory effect compared to the standard drug but both doses showed significant (*P&lt;0.05 vs. control) reduction in body temperature in the antipyretic study.

Chemical characterization, anti-nociceptive and anti-inflammatory activities of Plukenetia conophora seed oil in experimental rodent models

Ethnopharmacological relevanceThe seed of the African walnut, Plukenetia conophora Mull.-Arg is well-known for its nutritional and medicinal values. The seed oil is widely used in massages to relieve pain, as nerve tonic and to enhance sexual performance. ObjectiveThe study aimed at investigating the chemical profile, antinociceptive and anti-inflammatory activities of P. conophora oil (PCO). MethodsSeed oil of P. conophora was characterized using Gas-Liquid Chromatographic method (GC-MS) and oral acute toxicity evaluated at 2000 mg/kg. Antinociceptive effects were evaluated in hot plate, acetic acid and formalin-induced paw licking tests. The anti-inflammatory effects were investigated in egg albumin and carrageenan-, formalin and complete Freund adjuvant (CFA)-induced paw oedema models. The levels of pro-inflammatory cytokines in the fluid exudates were also evaluated in carrageenan air pouch model. ResultsPCO exhibited high content of alpha linolenic acid (ALA). No toxicity was observed at 2000 mg/kg of PCO. PCO (50–200 mg/kg) demonstrated significant anti-nociceptive activity in pain models. PCO exhibited anti-inflammatory activity against oedema formation by phlogistic agents. The increased inflammatory oedema and oxidative stress in CFA-treated rats were also attenuated by PCO. The PCO (100 and 200 mg/kg) significantly reduced the levels of TNF-α (59.3% and 85.2%) and IL-6 (27.5% and 72.5%) in carrageenan-induced air pouch model. ConclusionThe results of this study suggest that ALA-rich seed oil of Plukenetia conophora demonstrated anti-nociceptive and anti-inflammatory activities via inhibition of pro-inflammatory cytokines and oxidative stress, lending supportive evidences for its use in painful inflammatory conditions.

Insight into the possible mechanism(s) involved in the antinociceptive and antineuropathic activity of Descurainia sophia L. Webb ex Prantl essential oil

Ethnopharmacological relevanceDescurainia sophia (L.)(Brassicaceae), popularly known as “Khaksheer”, is a native species widely distributed in Iran. The seeds and essential oil has been used in local traditional medicine (Persian folk ethnomedicine) to treat fever, inflammation, back pain, and headache. Aim of the studyTo investigate in vitro anti-nociceptive and antineuropathic activities of Descurainia sophia seeds essential oil (DSEO) in rats and to determine the possible mechanism(s) involved. Materials and methodsThe antinociceptive activity of DSEO or Linolenic acid (LA) was evaluated using the formalin induced paw licking test followed by determination on the role of NO-cGMP-K+ channel pathway as well as a number of non-opioid receptor systems (vanilloid, dopamine, cannabinoid, serotonin, peroxisome proliferator activated, and adrenergic receptors) in the modulation of DSEO-induced antinociceptive activity. Additionally, the cervical spinal cord contusion (CCS) model was used to study antineuropathic potential of DSEO or LA. ResultsDSEO exerted significant (p < 0.05) antinociceptive activity in formalin test (both phases) and altered mechanical allodynia and hyperalgesia observed in the CCS model. Pretreatment with glibenclamide, Nω-nitro-L-arginine methyl ester, tranilast, methylene blue, SCH23390, SR141716A and SR144528 restored DSEO-induced antinociceptive activity observed in the formalin test. Furthermore, LA also reduced nociceptive responses induced in the formalin and CCS models. ConclusionDSEO inhibits inflammatory mediated nociceptive response partly via the modulation of NO-cGMP-K+ channels pathway well as the activation of vanilloid, dopamine, and cannabinoid receptors, and exerts antineuropathic activity possibly via the modulation of inflammatory mediated activity. Thus, these findings confirm the Persian ethno-medicine claim on the efficacy of D. Sophia.

Analgesic, anti-inflammatory and NF-\u03baB inhibitory activity of aerial parts of Cestrum diurnum

BackgroundCestrum diurnum L. (Solanaceae), locally known as buno-Hasnahena, is widely used in different traditional medicinal practices to treat pain, burn, swelling and related disorders. Adequate evidence is not available to support its medicinal properties for further use and drug development. Present study was designed to evaluate its traditional use in pain and inflammation with further characterisation of its chemical constituents through liquid chromatography-mass spectroscopic (LC-MS) analysis.MethodsAntinociceptive and analgesic potential of methanol extract of the aerial parts of C. diurnum was carried out using carrageenan induced paw oedema and formalin induced paw licking test in mice at the oral doses of 150 and 300 mg/kg body weight. Inhibition of the inflammatory mediator nuclear factor kappa B (NF-κB) was evaluated by tumour necrosis factor α (TNF-α) induced NF-κB activation assay in macrophage cells at the concentration of 100 μg/ml. LC-MS analysis of the extract was performed to characterise the active component responsible for bioactivities.ResultsThe extract significantly inhibited (p < 0.05) carrageenan induced paw oedema at both doses tested and the effect persisted throughout the entire experimental period of 3 h with the highest activity (50% inhibition) observed at 3rd h. Further, the extract significantly inhibited (p < 0.05) formalin induced paw licking both in the early and late phase at the aforementioned dose levels. The extract also downregulated the expression of NF-κB p65 protein in the TNF-α induced NF-κB activation assay. LC-MS analysis of the extract indicated the presence of some important secondary metabolites including nicotine, nornicotine, ursolic acid, vitamin D3 and its derivatives.ConclusionsThe results of this study supported the folkloric uses of the plant in pain and inflammations. The insights and observations suggest the action might involve downregulation of NF-κB p65 protein expression and/or inhibition of autacoids (histamine, serotonin, prostaglandin).

ViphyllinTM, a Standardized Black Pepper Seed Extract Exerts Antinociceptive Effects in Murine Pain Models via Activation of Cannabinoid Receptor CB2, Peroxisome Proliferator-Activated Receptor-Alpha and TRPV1 Ion Channels.

PurposePlant-based natural products as anti-nociceptors have enormous potential as safer alternatives to conventional opiates and NSAIDS. Piper nigrum (black pepper) is one of the major culinary spices with medicinal attributes.MethodsIn the present study, the antinociceptive activity of a standardized black pepper seed extract (Viphyllin) containing not less than 30% β-caryophyllene (BCP) was evaluated using pain models in mice, namely acetic acid-induced writhing test, formalin-induced paw licking test, hot plate test and tail flick test. Further, the antagonists SR141716A (0.1 mg/kg i.p.), AM630 (5 mg/kg i.p.), capsazepine (0.1 mg/kg body weight i.p.), and GW6471 (1 mg/kg i.p.) were used to evaluate the involvement of cannabinoid receptors CB1 and CB2, TRPV1 ion channel and PPARα receptor, respectively. Molecular docking (AutoDock 4.2) was used to study the interaction of BCP with the agonist-binding sites of the selected pain receptors.ResultsViphyllin at 10 mg, 25 mg and 50 mg/kg (i.p.) significantly inhibited the writhings in mice as compared to untreated control group (p < 0.001). Further, Viphyllin at 50 mg/kg showed strong antinociceptive effect in formalin-induced paw licking test (p < 0.05). Pretreatment of mice with AM630 significantly reversed the antinociceptive activity of Viphyllin in both early and late phases of formalin test (p < 0.05). Administration of Viphyllin markedly increased the latency time of mice in hot plate test (p < 0.001). Further, Viphyllin markedly increased the latency time of tail flick compared to control group from 30 min to 90 min after treatment. AM630, Capsazepine, and GW6471 abolished the analgesic effect of Viphyllin. These findings clearly suggest the involvement of CB2 receptor, TRPV1 ion channel and PPARα receptor activation in Viphyllin-mediated antinociceptive activity. Docking score predictions further supported the possible involvement of BCP in the antinociceptive mechanism of Viphyllin.ConclusionIn conclusion, Viphyllin could be a natural pain-relieving agent involving safer pain signaling mechanisms, unlike conventional opiates and NSAIDs.

Myristic acid reduces skin inflammation and nociception.

This study evaluated the inhibitory effect of myristic acid (MA) on models of inflammation and nociception. The in vitro anti-inflammatory activities of MA were assessed on LPS-stimulated macrophages, membrane stabilization assay, and inhibition of protein denaturation, whereas the inhibitory activity of MA on in vivo inflammation was assessed on TPA-induced ear edema using acute and chronic assays in mice. The inhibitory effect of MA on nociception was assessed using three in vivo models. MA exerted in vitro anti-inflammatory activity by the increase (58%) in the production of IL-10 in LPS-stimulated macrophages. In the in vivo assay, MA showed good anti-inflammatory effects on the acute (ED50 = 62mg/kg) and chronic (ED50 = 77mg/kg) TPA-induced ear edema. The antinociceptive activity of MA was related to the participation of the nitrergic system in the formalin-induced paw licking test. PRACTICAL APPLICATIONS: Previous studies with different plant extracts containing MA, as one of their major components, have demonstrated anti-inflammatory and antinociceptive actions. However, the anti-inflammatory and antinociceptive actions of myristic acid have not been previously reported. The results suggest that MA induced anti-inflammatory effects in LPS-stimulated macrophages through the participation of IL-10. The antinociceptive effects of MA are attributed to the participation of the nitrergic system.

Antinociceptive and Behavioural Effects of the Leaves of Milicia excelsa (Welw.) C. C. Berg (Moraceae)

The leaves of Milicia excelsa (Welw.) C. C. Berg (Moraceae) is used in the treatment of inflammatory and painful disorders and as sedative in the treatment of insanity in Nigerian traditional medicine. The antinociceptive activity of the ethanol extract (50, 100 and 200 mg/kg, p.o.) was investigated using acetic acid-induced writhing, hot plate and formalin-induced paw licking tests while the behavioural assessment was evaluated in holeboard, elevated plus maze and phenobarbitone-induced sleeping time tests. Acetylsalicylic acid, morphine or diazepam and 1% Tween 20 (10 mL/kg) were employed as positive and negative control respectively. Acute toxicity of the extract (200-3200 mg/kg, p.o.) was also determined.