Central Antinociceptive Activity Research Articles

Mechanisms of action of ethyl acetate fractions of Liparis nervosa (Thunb.) Lindl. as potential central anti-nociceptive agents.

Opioids/non-steroidal anti-inflammatory drugs are used to alleviate pain; however, they are expensive and can have adverse effects, especially when used over extended periods. Therefore, there is immense demand for innovative, non-addictive analgesics. Here, we report a novel plant-derived central anti-nociceptive agent, Liparis nervosa (Thunb.) Lindl. (LN), validated in animal pain models. Ethyl acetate fractions of L. nervosa (EALN) exhibited central anti-nociceptive activity in hot plate, tail immersion, formalin-induced paw oedema, and acetic acid-induced abdominal writhing tests. The chemical composition of the EALN was determined using ultra-high-performance liquid chromatography-mass spectrometry. Reserpine (monoamine transmitter-depleting agent) and naltrexone (opioid antagonist) partially suppressed the anti-nociceptive effect of EALN in both phases of the formalin test. Oral administration of EALN activated the endogenous opioid and central descending inhibitory systems by increasing β-endorphin, 5-hydroxytryptamine, and norepinephrine expression. EALN treatment increased the expression of γ-aminobutyric acid B; inhibited the expression of prostaglandin E2, substance P, calcitonin gene-related peptide, and c-Fos; and blocked the transmission of pain signals in the spinal cord. EALN treatment reduced the activity of nitric oxide and nitric oxide synthase in the central region and inhibited the nitric oxide-cyclic guanosine monophosphate signal transduction pathway, thereby attenuating the transmission of nociceptive information in the descending inhibitory pathways. The central anti-nociceptive effect of EALN was achieved by integrating these pathways. This study provides new insights into the pharmacologic action of LN and provide a therapeutic approach as a promising candidate for central anti-nociceptive agents.

Evaluation of Olea europaea L. and Tamarix aphylla leaves extracts in the management of pain, pyrexia and allergy in mice and rats

A huge amount of information, related to herbals is based exclusively on historical beliefs. Therefore, we aim to provide scientific validation for some of the traditional uses attributed to Olea europaea (OE) and Tamarix aphylla (TA). To achieve this, we conducted experiments to ensure the safety of the aqueous extract of OE and the methanolic extract of TA. Subsequently, we investigated the peripheral and central antinociceptive activity, antipyretic properties, and anti-allergic activities using albino mice and Wistar rats. Both plant extracts at the doses of 100, 200 and 400 mg produced potent antinociceptive activity (p < 0.05) in a dose-dependent manner using acetic acid-induced writhing reflex and tail immersion assay. Additionally, both plants produced remarkable antipyretic activity comparable with paracetamol (100 mg) manifested by a significant (p < 0.05) reduction of brewer’s yeast-induced pyrexia in rat. Both OE and TA resulted in a potent reduction in leukocytosis and eosinophilia induced by milk in mice.

Identification of a novel protein Hq023 of the hard tick Haemaphysalis qinghaiensis and preliminary evaluation of its analgesic effect in mice model

Tick saliva contains a range of critical biological molecules which could inhibit host defenses and guarantee their food supply. Hq023, a novel cDNA sequence, was cloned from a cDNA library constructed from salivary glands of partially-engorged Haemaphysalis qinghaiensis. Hq023 has an open reading frame (ORF) of 408 bp coding a protein containing 135 amino acid residues with a molecular mass of 15 kDa. Database homology showed that Hq023 protein was structurally similar to a natural toxin U33-theraphotoxin-Cg1c from the Chinese tarantula Chilobrachys guangxiensis. A recombinant protein was expressed with the novel cDNA in a prokaryotic system and its analgesic effect was evaluated in mice model. Both tail immersion and hot-plate tests uncovered an antinociceptive activity, while in the acetic acid-induced writhing test this effect was not observed. These results indicated that the novel recombinant protein Hq023 (rHq023) probably possessed a central antinociceptive activity. Finding of the novel protein might pave a new avenue for the development of tick-derived analgesics.

BNT12, a novel hybrid peptide of opioid and neurotensin pharmacophores, produces potent central antinociception with limited side effects

The development of multitarget opioid drugs has emerged as an attractive approach for innovative pain management with reduced side effects. In the present study, a novel hybrid peptide BNT12 containing the opioid and neurotensin (NT)-like fragments was synthesized and pharmacologically characterized. In acute radiant heat paw withdrawal test, intracerebroventricular (i.c.v.) administration of BNT12 produced potent antinociception in mice. The central antinociceptive activity of BNT12 was mainly mediated by μ-, δ-opioid receptor, neurotensin receptor type 1 (NTSR1) and 2 (NTSR2), supporting a multifunctional agonism of BNT12 in the functional assays. BNT12 also exhibited significant antinociceptive effects in spared nerve injury (SNI)-neuropathic pain, complete Freund's adjuvant (CFA)-induced inflammatory pain, acetic acid-induced visceral and formalin-induced pain after i.c.v. administration. Furthermore, BNT12 exhibited substantial reduction of acute antinociceptive tolerance, shifted the dose-response curve to the right by only 1.3-fold. It is noteworthy that BNT12 showed insignificant chronic antinociceptive tolerance at the supraspinal level. In addition, BNT12 exhibited reduced or no opioid-like side effects on conditioned place preference (CPP) response, naloxone-precipitated withdrawal response, acute hyperlocomotion, motor coordination, gastrointestinal transit, and cardiovascular responses. The present investigation demonstrated that the novel hybrid peptide BNT12 might serve as a promising analgesic candidate with limited opioid-like side effects.

Hyaluronic acid from bluefin tuna by-product: Structural analysis and pharmacological activities

The fishing and aquaculture industries generate a huge amount of waste during processing and preservation operations, especially those of tuna. Recovering these by-products is a major economic and environmental challenge for manufacturers seeking to produce new active biomolecules of interest. A new hyaluronic acid was extracted from bluefin tuna's vitreous humour to assess its antioxidant and pharmacological activities. The characterization by infrared spectroscopy (FT-IR), nuclear magnetic resonance ((1D1H) and 2D (1H COSY, 1H/13C HSQC)) and size exclusion chromatography (SEC/MALS/DRI/VD) revealed that the extracted polysaccharide was a hyaluronic acid with high uronic acid content (55.8 %) and a weight average molecular weight of 888 kDa. This polymer possesses significant anti-radical activity and ferrous chelating capacity. In addition, pharmacological evaluation of its anti-inflammatory and analgesic potential, using preclinical models, in comparison with reference drugs (Dexamethasone, diclofenac, and acetylsalicylate of lysine), revealed promising anti-inflammatory activity as well as interesting peripheral and central antinociceptive activity. Therefore, our new hyaluronic acid compound may therefore serve as a potential drug candidate for the treatment of pain sensation and inflammation of various pathological origins.

Evaluation of the anodyne effect of Terminalia bellirica fruit pulp in mouse models of Swiss albino strain

Background: Terminalia bellirica has been extensively investigated and used since time immemorial as part of Ayurvedic practice entirely because of its curable properties. Their antioxidant, hepatoprotective, antibacterial, and immunemodulatory activities are mostly attributed to the presence of glucoside, gallic acid, and its esters, chebulinic acid, etc. Aims and Objectives: The aim of the study is to analyze the effects of sub-acute administration of T. bellirica fruit pulp aqueous extract (TBFPAE) in ameliorating pain in mouse models of the Swiss albino strain. Materials and Methods: Young mice of Swiss albino strain typically 3 months’ of age; Male gender and weighing approximately 20–30 g were used for the purpose of the study. The mice were investigated by grouping them into five sets of six each randomly as control, standard, and trial groups. Group I was allotted as vehicle and given 1% gum acacia (10 mL/kg) as control; Group II was given pentazocine (5 mg/kg) as standard for central anti-nociceptive activity, while the IIIrd, IVth, and Vth groups received the investigative product TBFPAE per oral in doses of 9, 18 and 36 mg/kg, respectively. Eddy’s hot plate technique was employed for assessing central anodyne activity. Results: All the test groups of TBFPAE were found to have an analgesic effect but doses 18 mg/kg and 36 mg/kg demonstrated greater effects, especially at 30 and 60 min. Maximum analgesic effect with TBFPAE was seen with 36 mg/kg dose at 60 min. Conclusion: Therefore, T. bellirica has some analgesic potential. However, further studies are required to confirm its dose and usage.

Analgesic effect of Centaurium erythraea and molecular docking investigation of the major component swertiamarin

Centaurium erythraea Rafn is employed in Algerian traditional medicine for treating pain. The analgesic activity of the ethanolic extract (EE) from the flowering aerial parts of this plant was examined, and molecular docking of the main bioactive compound was performed. The EE, characterised by the iridoid swertiamarin, was administered to Wistar albino rats in pain models. Peripheral analgesic activity was evaluated using the acetic acid-induced writhing test, and a hot plate test was performed for central antinociceptive activity evaluation. Treatment with EE significantly decreased rats’ writhing induced by acetic acid suggesting peripheral analgesic activity. Furthermore, the elevation of mean basal reaction time in the hot plate method indicated central analgesic activity. Molecular docking studies showed good docking energy with acceptable binding interactions of swertiamarin with cyclooxygenase-2 protein. This supports the analgesic activity of C. erythraea EE, justifying the traditional use of the plant as an analgesic herbal remedy.

Chemical composition and antinociceptive and anti-inflammatory activity of the essential oil of Hyptis crenata Pohl ex Benth. from the Brazilian Amazon

Ethnopharmacological relevanceThe leaf tea of Hyptis crenata has its practical use in the Brazilian Amazon for treating gastrointestinal and liver disorders, sweating induction, and as an anti-inflammatory. Aim of the studyEvaluation of the chemical composition, acute oral toxicity, and antinociceptive and anti-inflammatory activities of the H. crenata essential oil. Material and methodsThe essential oil was hydrodistilled and analyzed by GC and GC-MS. The antinociceptive action in mice was evaluated for the peripheral and central analgesic activity (abdominal contortion and hot plate tests), and the xylene-induced ear swelling was carried out for the nociception test. ResultsOxygenated monoterpenes (53.0%) and monoterpene hydrocarbons (38.9%) predominated in the H. crenata oil, being 1,8-cineo1e (35.9%), α-pinene (20.8%), camphor (10.0%), and β-pinene (7.3%) their primary constituents. The oral oil administration in the mice did not display changes in behavior patterns or animal mortality at 300 and 2000 mg/kg doses. The control group's biochemical parameters (ALP, AST, ALT) displayed a statistical difference from the treated group, unlike the renal parameters, which showed no variation between the groups. Oil reduced the abdominal contortions at doses of 100 (79.5%) and 300 mg/kg (44.4%), while with endodontacin, the dose was 5 mg/kg (75.2%). In addition, the oil could not decrease the paw licking/biting time at doses of 30, 100, and 300 mg/kg. However, it showed a significant antinociceptive effect on the second phase in the formalin test inhibiting licking time, with a reduction of 50.8% (30 mg/kg), 63.4% (100 mg/kg), 58.0% (300 mg/kg), and morphine (4 mg/kg, 78.3%). The oil administration produced significant inhibition of ear edema at all tested doses, with a better effect produced at 30 mg/kg (64.0% inhibition). ConclusionThe oil of Hyptis crenata, rich in 1,8-cineole, camphor, α-pinene, and β-pinene, totaling 74%, displayed low acute toxicity and significant anti-inflammatory activity, with peripheral and no central antinociceptive action. Thus, these results show an actual perspective on using H. crenata oil in developing a phytotherapeutic product.

Anti-inflammatory, antinociceptive effects and involvement of opioid receptors in the antinociceptive activity of Eugenia uniflora leaves obtained with water, ethanol, and propylene glycol mixture

Ethnopharmacological relevanceEugenia uniflora (Myrtaceae) is a species native to Brazil and has a traditional use in the treatment of inflammation. Aim of the studyTo evaluate the anti-inflammatory and antinociceptive effects, and the involvement of opioid receptors in the antinociceptive activity of extract and fractions from Eugenia uniflora leaves. Materials and methodsTLC and HPLC were used to characterize the spray-dried extract (SDE) and fractions. In the in vivo assays, Swiss (Mus musculus) mice were used. Carrageenan-induced hind-paw edema and carrageenan-induced peritonitis models were used to determine the anti-inflammatory effect of the extract (50, 100, or 200 mg/kg). Acetic acid-induced writhing, tail-flick, and formalin tests were used to determine the antinociceptive effect of the extract (50, 100, or 200 mg/kg). The aqueous (AqF) and ethyl acetate (EAF) fractions (6.25, 12.5, and 25 mg/kg) were then combined with naloxone to evaluate the involvement of opioid receptors in the antinociceptive activity. ResultsIn this work, the TLC and HPLC analysis evidenced the enrichment of EAF, which higher concentration of gallic acid (5.29 ± 0.0004 %w/w), and ellagic acid (1.28 ± 0.0002 %w/w) and mainly myricitrin (8.64 ± 0.0002 %w/w). The extract decreased the number of total leukocytes and neutrophils in the peritoneal cavity (p < 0.05), at doses of 100 and 200 mg/kg and showed significant inhibition in the increase of paw edema volume (p < 0.05). The treatment per oral route (doses of 50, 100, and 200 mg/kg) significantly reduced the nociceptive response in acetic acid-induced abdominal writhing (p < 0.05). The effect of the extract on the tail-flick test showed a significant increase in latency time of animals treated at doses of 200 and 100 mg/kg (p < 0.05). The extract and ethyl acetate fraction reduced the nociceptive effect in both phases of formalin at all tested doses. The naloxone reversed the antinociceptive effect of EAF, suggesting that opioid receptors are involved in mediating the antinociceptive activity of EAF of E. uniflora in the formalin test. ConclusionThe current study demonstrates the anti-inflammatory and analgesic activities of water: ethanol: propylene glycol spray-dried extract from E. uniflora leaves using in vivo pharmacological models in mice. Our findings suggest that spray-dried extract and ethyl acetate fraction exhibit peripheral and central antinociceptive activity with the involvement of opioid receptors that may be related to the presence of flavonoids, mainly myricitrin.

Antinociceptive and Anti-Inflammatory Activity of Beta-Sitosterol

Background: Phytosterols are commonly present in various plants, among which sitosterol is the abundant one. Various extracts of leaves of the plant were screened but a purified phytosterol like β-sitosterol (BS) is a compound of interest. Objective: The aim of the study is to evaluate for analgesic and anti-nociceptive property of activity BS. Materials and Methods: Hot plate test and Acetic acid-induced writhing’s test was used for evaluating the central and peripheral Antinociceptive activity and Anti-inflammatory activity was evaluated by carrageenan-induced hind paw edema method. Results: BS (10 and 20 mg/kg, i.p.) was responsible for the significant and dose-dependent activity comparable with the standard. Conclusion: The dose dependent activity of β-sitosterol might be responsible for analgesic and anti-inflammatory activity, this may also be a vital observation for further studies.

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.

A Mechanistic Approach to Anti-nociceptive Potential of Nymphaea lotus Linn (Nymphaeaceae) in Rodents

Background: Nymphaea lotus Linn. (Nymphaeaceae), commonly known as white water-lily, white lotus or Egyptian lotus, is an important and well-known medicinal plant, widely used in the Ayurveda and Siddha systems of medicine for the treatment of diabetes, inflammation, liver disorders, urinary disorders, fever, skin diseases, cancer, gonorrhoea, pain and bronchitis. Objective: The study was designed to explore anti-nociceptive potential of aqueous extract of Nymphaea lotus leaf, its possible mechanism of action, and antioxidant properties. Methods: The anti-nociceptive activity of Nymphaea lotus (50, 100 and 250 mg/kg) was explored using writhing, formalin, tail clip and hot plate tests, while formalin test was used to investigate the involvement of opioid, dopamine, serotonin, K+ channel blocker, α1-adrenergic and α2- adrenergic systems. The antioxidant effect was carried out using DPPH, nitric oxide free radical scavenging activity and the reducing power effect. Total phenolic and flavonoids contents were also explored. Results: Oral administration of N. lotus in doses of 50, 100 and 250 mg/kg recorded a significant (p&lt;0.05) dose dependent obstruction of nociception. A remarkable effect was recorded with the writhing and formalin tests and a significant effect was also observed in the tail clip and hot plate test, which suggests peripheral and central anti-nociceptive activity of the extract. The anti-nociceptive effect produced by N. lotus was significantly reversed by naloxone and yohimbine, suggesting the possible involvement of opioid and α2–adrenergic systems in its anti-nociceptive activity. N. lotus also displayed a potent antioxidant activity. Conclusion: These findings justify the folkloric use of N. lotus in pain management.

Anti-nociceptive activity of ethanol leaf extract of Smilax anceps in swiss albino mice

Smilax anceps is traditionally used in the management of rheumatism. Anti-nociceptive activity of the ethanol extract of the leaf of this plant was investigated. Phytochemical screening and acute toxicity (LD50) of the extract were determined. The acetic acid induced writhing and hotplate test were used to evaluate the anti-nociceptive activity in Swiss mice. Fifty animals divided into twenty-five each were used for each assay. Acetylsalicylic acid and tramadol were used as reference drugs while extract was administered at 250, 500 and 1000mg/kg doses via the oral route in writhing and hotplate test respectively. Flavonoids, tannins, saponins and steroids/triterpenoids were found as phytoconstituents. In acetic acid induced writhing test, a statistically significant (P&lt;0.05) difference in anti-nociceptive activity was observed between the test groups and the negative control. However, the extract at 250mg/kg showed a statistically significant (P&lt;0.05) difference in anti-nociceptive activity when compared to the positive control. In the hotplate test, all extract treated groups exhibited a statistically significant (P&lt;0.05) difference when compared to the negative control. Meanwhile, the 250mg/kg extract dose exhibited non-significant increase in latency at the 90,120 and 150minute when compared with the positive control. The findings of this study have shown that ethanol leaf extract of Smilax anceps might possess significant peripheral and central anti-nociceptive activities.

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

Ethnopharmacological relevanceBougainvillea 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 studyThis 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 methodsThe 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. ResultsOur 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. ConclusionTaken 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.

In vivo and in silico evaluation of antinociceptive activities of seed extract from the Holarrhena antidysenterica plant

The objective of the study was to investigate the analgesic activity of seeds extracted from the Holarrhena antidysenterica plant (Family: Apocynaceae). The seeds of H. antidysenterica were extracted with pure ethanol and administered to the experimental Swiss albino mice at three different doses (50, 100, and 150 mg/kg body weight) in pain models. Peripheral analgesic activity was evaluated using the acetic acid-induced writhing test, and heat-induced (hot plate and tail immersion test) pain models were applied for central anti-nociceptive activity evaluation. Formalin induced licking test was applied to evaluate both peripheral and central anti-nociceptive activity on mice. Computational studies were performed by Schrödinger Maestro v10.1 for molecular docking and the SwissADME online server for ADME prediction of compounds. In acetic acid-induced writhing test, dose-dependent reduction of writhing response was observed with 43.94% (p < 0.001) writhing inhibition at 150 mg/kg dose compared to standard 60.98% (p < 0.001). 150 mg/kg caused a maximum decrease in licking and biting time in both early and late phases of the formalin-induced licking test (71.2 ± 5.67, p < 0.05, and 36.6 ± 5.62, p < 0.01 respectively). In both tests of central analgesic activity, the extract also showed dose-dependent anti-nociceptive activity. In the hot plate method, the highest %MPE was 67.39 (p < 0.001) at 30 min at 150 mg/kg dose, which was even better than the standard drug. In the case of the tail immersion method, the highest %MPE was 69.84 at a dose of 150 mg/kg at 30 min (p < 0.001). In molecular docking study, Conimine, Conarrhimin, Conessine, and Funtudienine showed the best binding affinities against the COX-1 enzyme. The study indicates that the ethanolic seed extract of H. antidysenterica has the strong potentiality of having central analgesic activity and moderate peripheral analgesic activity due to the presence of bioactive compounds in its seeds.

Pharmacological evidence for the use of Cissus assamica as a medicinal plant in the management of pain and pyrexia

The existing therapeutic agents for the management of pain and pyrexia are not very efficient and accompanied by numerous side effects. Thus, new effective agents are the most needed. The present study investigates bioactivities and phytochemical screening of different parts of Cissus assamica (Vitaceae), a Bangladeshi tribal medicinal plant. Three plant parts stems, leaves and roots were collected, washed, dried, powdered and then prepared for cold extraction. The methanolic stems and leaves extracts were fractioned with four and two solvents respectively. Different plant extracts were then investigated for in vivo antinociceptive activity and only methanolic leaves extract was investigated for in vivo antipyretic activity. In Swiss-albino mice, 200 and 400 mg/kg body weight doses were used for all extracts. In the peripheral antinociceptive activity, the methanolic stem extract and its dichloromethane, chloroform, pet ether fractions and methanolic roots extract at their both doses showed significant antinociceptive responses when compared to standard diclofenac sodium (60.49% inhibition). In the central antinociceptive activity, the response was found significant for methanolic stem and methanolic roots extract in their both doses compared to standard morphine. In antipyretic activity, methanolic leaves extract significantly reduced pyrexia level at 400 and 200 mg/kg body weight doses after two, three and 4 h of administration when compared to standard. So our findings indicate that this plant possesses noteworthy pharmacological activities which may be a basis for further researches to establish a possible mode of action of its different parts.

Acetyl-L-carnitine in painful peripheral neuropathy: a systematic review.

Acetyl-L-carnitine (ALC) has shown a neuroprotective effect in patients with peripheral neuropathies of different etiologies. Preclinical studies demonstrated a central anti-nociceptive action, both in neuropathic and nociceptive pain models. The present review aims to provide the knowledge on the efficacy of ALC in patients with painful peripheral neuropathy, based on the evidence. Consistent with the PRISMA statement, authors searched PubMed, Embase and the Cochrane Database of Systematic Reviews for relevant papers, including those issued before April 2018. Two authors independently selected studies for inclusion and data extraction: only trials including patients with a diagnosis of peripheral neuropathy and involving at least 10 patients were considered for the purposes of this review. Fourteen clinical trials were revised, to provide the level of evidence for neuropathy. To assess the global efficacy of ALC in painful peripheral neuropathy, a meta-analysis of four randomized controlled trials was performed. Mean difference in pain reduction as measured on a 10-cm VAS, and 95% CIs were used for pooling continuous data from each trial. Four randomized controlled trials tested ALC in patients with neuropathy secondary to diabetes and to antiretroviral therapy for HIV. Compared to placebo, ALC produced a significant pain reduction equal to 20.2% (95% CI: 8.3%-32.1%, P<0.0001) with respect to baseline. Clinical trials also showed beneficial effects on nerve conduction parameters and nerve fiber regeneration, with a good safety profile. These data indicate that ALC provides an effective and safe treatment in patients with painful peripheral neuropathy. We recommend further studies to assess the optimal dose and duration of the therapeutic effect (also after treatment withdrawal).

Antinociceptive and Anthelmintic Activities of Leaves of Leea aequata

The objective of the study was to evaluate the antinociceptive and anthelmintic activities of the crude methanol extract of leaves of Leea aequata and its fractions. The crude extract and its fractions at 200- and 400-mg/kg bw were subjected to assay for their antinociceptive activity using acetic acid induced writhing and radiant heat tail flicking methods. The ethyl acetate soluble fraction at 400 mg/kg bw induced 40.97% inhibition of writhing in mice while the carbon tetrachloride and chloroform soluble fractions of crude extract at the same dose displayed activity with 40.28% inhibition of writhing as compared to standard diclofenac sodium. The crude extract elongated the reaction time by 57.04% after 30 minute of administration in radiant heat tail flicking method, which suggested the central antinociceptive activity as compared to morphine. The methanol extract of the leaves of L. aequata exhibited profound anthelmintic activity in a dose dependent manner with shortest time of paralysis and death at 100 mg/ml concentration. It caused paralysis of the earthworm Pheretima posthuma at 9.44 min and death at 12.9 min when compared to the standard drug albendazole, which at 10 mg/ml concentration revealed the same at 8.21 minutes and 11.18 minutes, respectively.&#x0D; Dhaka Univ. J. Pharm. Sci. 17(2): 251-255, 2018 (December)

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.

Ethanolic extract of the aerial parts of Passiflora cincinnata Mast. (Passifloraceae) reduces nociceptive and inflammatory events in mice

BackgroundPassiflora cincinnata Mast. is described as a native species from the Caatinga biome, and used by traditional medicine for several pharmacological purposes, such as inflammatory disorders. However, studies that prove its biological activities are scarce. Hypothesis/purposeThis paper aims to evaluate the antinociceptive and anti-inflammatory activities of the aerial parts of Passiflora cincinnata (Pc-EtOH) in mice. MethodsThe chemical composition of Pc-EtOH was assessed by high-performance liquid chromatography coupled to diode array detector (HPLC-DAD). The antinociceptive profile of the extract (given orally: 100, 200 and 400 mg/kg) was established using the in vivo chemical models (acetic acid-induced abdominal constriction and formalin-induced paw licking test) and thermal (hot plate test) of nociception. The role of opioid, potassium channels, TRPV-1, muscarinic, serotoninergic (5-HT3) receptors and the participation of the nitric oxide pathway also was determined. The rota-rod test was used to verify the possible interference of the extract treatment in motor performance. Paw edema induced by carrageenan or histamine, and leukocyte migration, determination of total protein and nitric oxide to the peritoneal cavity were used for anti-inflammatory profile. ResultsThe presence of flavonoids in the extract was confirmed using HPLC-DAD. At all doses tested the Pc-EtOH significantly reduced the number of writhing and decreased the paw licking time in both phases of the formalin test (p < 0.05). In the hot plate test, the extract increased the reaction time, reducing painful behavior. The antinociceptive mechanism probably involves central and peripheral pathways, involving the pathway of opioid and muscarinic receptors with influence of potassium channels and the nitric oxide pathway. However, the motor coordination test indicated that in the time of 120 min the extract decreases the stay time of the animal in the rota-rod. Pc-EtOH inhibited significantly (p < 0.05) the increase of the edema volume after administration of carrageenan and histamine. In the peritonitis test, acute pre-treatment with Pc-EtOH inhibited leukocyte migration, with a reduction in the number of neutrophils and concentration of total proteins and nitric oxide. ConclusionThe present study suggests that Pc-EtOH possesses peripheral and central antinociceptive action, and showed potential in inhibition of release of mediators of the inflammatory process.