Antinociceptive Tests Research Articles

Sulfated polysaccharide extracted from the alga Gracilaria domingensis modified with propionic anhydride negatively modulates acute inflammation and experimental hypernociception

Sulfated polysaccharides (PLSs) from marine algae represent a broad class of compounds with pharmacological interest, due to their therapeutic properties. PLSs have hydrophilic chains containing various chemical groups of several compositions that differ structurally and in their physicochemical and biological effects. However, this hydrophilic nature of PLSs is also responsible for some limitations in the use of these compounds. To overcome these disadvantages, PLSs can be chemically modified by grafting groups that can give the compound a more hydrophobic nature. In the present study, the PLS from Gracilaria domingensis was modified with propionic anhydride (PLS-AP) and underwent complementary characterizations by scanning electron microscopy, X-ray diffraction, infrared spectral analysis and elemental analysis. The reaction with propionic anhydride increased crystallinity and produced a chemically modified polysaccharide with new carbon, hydrogen and sulfur groups. The new characteristic of the compound may have added interesting properties to PLS, such as increased stability, amphiphilic nature and increased sulfate content, which in red marine algae SPSs produce biological activity. Regarding biological properties, PLS-AP (2.5 mg/kg) significantly reduced paw edema induced by carrageenan, histamine, serotonin, bradykinin and prostaglandin E2, as well as improved microscopic tissue damage criteria. The modified compound was also able to significantly decrease neutrophil migration, myeloperoxidase, and malondialdehyde concentrations and preserved glutathione levels in peritoneal fluid during induced peritonitis. Additionally, in antinociceptive tests, PLS-AP reduced the number of contortions induced by acetic acid and the response time to formalin-induced paw licking. Thus, PLS-AP may be a promising substance to treat inflammatory conditions.

Fresh Carrier for an Old Topical Local Anesthetic: Benzocaine in Nanostructured Lipid Carriers.

Nanostructured lipid carriers (NLC) have emerged as innovative drug delivery systems, offering distinct advantages over other lipid-based carriers, such as liposomes and solid lipid nanoparticles. Benzocaine (BZC), the oldest topical local anesthetic in use, undergoes metabolism by pseudocholinesterase, leading to the formation of p-aminobenzoic acid, a causative agent for allergic reactions associated with prolonged BZC usage. In order to mitigate adverse effects and enhance bioavailability, BZC was encapsulated within NLC. Utilizing a 23 factorial design, formulations comprising cetyl palmitate (solid lipid), propylene glycol monocaprylate (liquid lipid), and Pluronic F68 as surfactants were systematically prepared, with variations in the solid/liquid lipid mass ratios (60:40-80:20%), total lipid contents (15-25%), and BZC concentrations (1-3%). The optimized formulation underwent characterization by dynamic light scattering, differential scanning calorimetry, Raman imaging, X-ray diffraction, small-angle neutron scattering, nanotracking analysis, and transmission electron microscopy (TEM)/cryo-TEM, providing insights into the nanoparticle structure and the incorporation of BZC into its lipid matrix. NLCBZC exhibited a noteworthy encapsulation efficiency (%EE = 96%) and a 1 year stability when stored at 25 °C. In vitro kinetic studies and in vivo antinociceptive tests conducted in mice revealed that NLCBZC effectively sustained drug release for over 20 h and prolonged the anesthetic effect of BZC for up to 18 h. We therefore propose the use of NLCBZC to diminish the effective anesthetic concentration of benzocaine (from 20 to 3% or less), thus minimizing allergic reactions that follow the topical administration of this anesthetic and, potentially, paving the way for new routes of BZC administration in pain management.

Lippia alba essential oil: A powerful and valuable antinociceptive and anti-inflammatory medicinal plant from Brazil

Ethnopharmacological relevanceIn Brazilian popular medicine, Lippia alba leaves are used in teas to treat pain and inflammatory diseases. Aim of the studyto evaluate the chemical composition, antinociceptive, and anti-inflammatory activities of Lippia alba essential oil and its major compound geraniol. Material and methodsLippia alba leaves were collected in Pará state, Brazil. The leaf essential oil was obtained using a modified Clevenger-type extractor. Then, the oil was analyzed by GC and GC-MS analyses. To evaluate the toxicity of LaEO and geraniol, the doses of 50, 300, and 2000 mg/kg were used in a mouse model. For antinociception tests, abdominal contortion, hot plate, and formalin tests were used; all groups were treated with LaEO and geraniol at doses of 25, 50, and 100 mg/kg; and to evaluate inflammation using the ear edema model. ResultsThe constituents identified in the highest content were oxygenated monoterpenes: geraniol (37.5%), geranial (6.7%) and neral (3.8%). The animals treated with LaEO and geraniol demonstrated atypical behaviors with aspects of lethargy and drowsiness, characteristics of animals in a state of sedation; the relative weights showed no significant difference compared to the controls. In the abdominal contortion test, LaEO at 25 mg/kg, 50 mg/kg doses, and 100 mg/kg reduced the number of contortions, representing a percentage reduction of 84.64%, 81.23%, and 66.21% respectively. In the hot plate test, LaEO and geraniol increased the latency time at doses of 25, 50, and 100 mg/kg in all test periods; there was no statistical difference between LaEO and geraniol. In the first phase of the formalin test, only doses of 25 mg/kg and 100 mg/kg of LaEO showed significant activity, reducing the latency time by 53.40% and 58.90%. LaEO at doses of 25 mg/kg and 100 mg/kg reduced the size of the edema, demonstrating an anti-inflammatory activity of 59.38% (25 mg/kg) and 50% (100 mg/kg). ConclusionLippia alba essential oil and geraniol showed central/peripheral analgesic and anti-inflammatory potential and can be used as an alternative or complementary treatment to conventional drugs. More studies are needed to evaluate its action mechanisms and its analgesic effects.

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 & 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.

Development of fentanyl-specific monoclonal antibody (mAb) to antagonize the pharmacological effects of fentanyl

Fentanyl, a critical component of opioid analgesics, poses a severe threat to public health, exacerbating the drug problem due to its potential fatality. Herein, we present two novel haptens designed with different attachment sites conjugated to keyhole limpet hemocyanin (KLH), aiming to develop an efficacious vaccine against fentanyl. KLH-Fent-1 demonstrated superior performance over KLH-Fent-2 in antibody titer, blood-brain distribution, and antinociceptive tests. Consequently, we immunized mice with KLH-Fent-1 to generate fentanyl-specific monoclonal antibodies (mAbs) using the hybridoma technique to compensate for the defects of active immunization in the treatment of opioid overdose and addiction. The mAb produced by hybridoma 9D5 exhibited the ability to recognize fentanyl and its analogs with a binding affinity of 10−10 M. Subsequently, we developed a human IgG1 chimeric mAb to improve the degree of humanization. Pre-treatment with murine and chimeric mAb significantly reduced the analgesic effect of fentanyl and altered its blood-brain biodistribution in vivo. Furthermore, in a mouse model of fentanyl-induced respiratory depression, the chimeric mAb effectively reversed respiratory depression promptly and maintained a certain level during the week. The development of high-affinity chimeric mAb gives support to combat the challenges of fentanyl misuse and its detrimental consequences. In conclusion, mAb passive immunization represents a viable strategy for addressing fentanyl addiction and overdose.

Antinociceptive effect and anti-inflammatory activity of 1,4-naphthoquinones in mice

Aim: The ability of synthetic 1,4-naphthoquinones (1,4-NQs) to prevent adenosine triphosphate (ATP)-induced and purinergic P2X7 receptor (P2X7R) mediated inflammation in macrophage and neurodegeneration of neuronal cells in vitro was previously established. The aim of the present study was to investigate analgesic-like and anti-inflammatory activity of 1,4-NQs thioglucoside derivatives, compounds U-286 and U-548, in in vivo experiments. Methods: Spectrofluorimetry approach and YO-PRO-1 fluorescent dye uptake determination were applied to study the effect of 1,4-NQs upon ATP-induced P2X7R mediated macropore formation in mouse neuroblastoma Neuro-2a cells and macrophages RAW 264.7 cells. An acetic acid-induced writhing test, hot plate test, and carrageenan-induced paw edema test were used as an in vivo mouse models to study the ability of 1,4-NQs to inhibit pain and inflammation. In the in vivo experiments, compounds were administered to mice intraperitoneally at dosages of 0.1 mg/kg, 1.0 mg/kg and 10.0 mg/kg. A group of animals that received injections of sterile water was used as a control. Each dosage group and the control group consisted of 6 mice. Results: In the present work the analgesic-like and anti-inflammatory activity of 1,4-NQs, U-286 and U-548, was demonstrated. Compound U-548 showed a significant inhibitory effect in antinociceptive tests reducing the number of mouse writhings and eliminating the latent time of mouse hind paw licking, correspondingly. Selected compounds were able to almost completely reduce the size of carrageenan-induced paw edema 24 h after injection and had a potent anti-inflammatory activity. Observed effects were accompanied with aptitude of studied 1,4-NQs to inhibit the formation of purinergic P2X7R macropore associated with inflammation and nociceptive pain. Conclusions: The results obtained allow to consider compounds U-286 and U-548 and as a pharmacological basis for the development of new analgesic-like and anti-inflammatory drugs.

Topical Analgesic and Anti-Inflammatory Properties of Bioengineered Juglans regia L. Silver Nanoparticles.

<b>Background and Objective:</b> Research has demonstrated the antibacterial, anti-angiogenetic, antiviral, anti-inflammatory, anticancer and antioxidant properties of colloidal silver due to its biological, optical and electrical properties. The aim of this study was the anti-inflammatory effect of the silver bioengineered nanoparticles by using the acetonitrile-unripe fruit extract of <i>Juglans regia</i> L., on experimental animal model. <b>Materials and Methods:</b> The study uses various techniques to characterize nanoparticles, including ultraviolet spectra, dynamic light scattering and Fourier transform infrared. The study used carrageenan-induced rat paw edema as an induction model for inflammation and assessed its antinociceptive effects in mice using the formalin test. As well as evaluation of proinflammatory cytokines IL-6, TNF and IL-1. <b>Results:</b> The produced AgNPs were more compact and stable, according to physical characterization methods compared to chemical prepared nanoparticles. The formulation combining unripe fruit bio-reduced nanoparticles and extract, UF, shows a greater acute anti-inflammatory effect, while leaf extract has a better late anti-inflammatory effect. These bioengineered nanoparticles show efficient <i>in vivo</i> anti-acute inflammation, reducing skin inflammation through decreased cellular infiltrates and cytokine release. <b>Conclusion:</b> <i>Juglans regia</i> L., extract and silver nanoparticles show notable effects in both the early and late stages of the antinociceptive formalin test. While, bioengineered NP/UF and NP/LV can be used as topical analgesics. The potent topical anti-inflammatory and analgesic effects of these medications provide a sufficient basis for the use of this plant material in dermatological products.

ATP-induced hypothermia improves burn injury and relieves burn pain in mice

Thermal burn injury is a severe and life-threatening form of trauma that presents a significant challenge to clinical therapy. Therapeutic hypothermia has been shown to be beneficial in various human pathologies. Adenosine triphosphate (ATP) induces a hypothermic state that resembles hibernation-like suspended animation in mammals. This study investigates the potential protective role of ATP-induced hypothermia in thermal burn injury. Male C57BL/6 mice underwent a sham procedure or third-degree burn, and ATP-induced hypothermia was applied immediately or 1 h after burn injury. Our results show that ATP-induced hypothermia significantly improved burn depth progression and reduced collagen degradation. Moreover, hypothermia induced by ATP alleviated burn-induced hyperinflammatory responses and oxidative stress. Metabolomic profiling revealed that ATP-induced hypothermia reversed the shifts of metabolic profiles of the skin in burn mice. In addition, ATP-induced hypothermia relieved nociceptive and inflammatory pain, as observed in the antinociceptive test. Our findings suggest that ATP-induced hypothermia attenuates burn injury and provides new insights into first-aid therapy after thermal burn injury.

Blockade of orexin receptor type-1 by SB-334867 and activation of orexin receptor type-2 attenuate morphine tolerance in rats.

The interaction of orexinergic neurons with the opioidergic system and their effects on morphine analgesia and tolerance have not been fully elucidated. The purpose of the study was to evaluate the effects of the orexin-1 and orexin-2 receptor (OX1R and OX2R) agonist and antagonist on morphine analgesia and tolerance in rats. A total of 90 Wistar albino male rats weighing 180-220 g wereused in the experiments. To induce morphine tolerance, rats were injected with a single dose of morphine (50 mg kg-1, s.c.) for 3 days. Morphine tolerance was assessed on day 4 in randomly selected rats by analgesia tests. In order to evaluate morphine tolerance situation, orexin-A, SB-334867, orexin-B andTCSOX2 29 were administered together with morphine for 3 days. The analgesic effects of orexin-A (10 μg kg-1), OXR1 antagonist SB-334867 (10 mg kg-1), OXR2 agonist orexin-B (15 μg kg-1), OXR2 antagonist TCS OX2 29 (0.5 mg kg-1) and morphine (5 mg kg-1) were measured at 15 or 30-min intervals by tail-flick and hot-plate antinociceptive tests. The results suggested that the combination of orexin-1 receptor antagonist SB-334867 and orexin-B with morphine significantly increased the analgesic effect compared to morphine-tolerant rats. In addition, administration of orexin-A and -B alone showed significant analgesic effects compared to the saline group. However, co-administration of orexin-A and -B with morphine didnot increase the analgesic efficacy of morphine. The results of this study demonstrated that co-administration of SB-334867 and orexin-B with morphine attenuated morphine tolerance. Further studies are needed to elucidate the details of the interaction between orexin receptors and the opioidergic system.

Metformin prevents morphine-induced apoptosis in rats with diabetic neuropathy: a possible mechanism for attenuating morphine tolerance.

Morphine is a drug of choice for the treatment of severe and chronic pain, but tolerance to the antinociceptive effect limits its use. The development of tolerance to morphine has recently been associated with neuronal apoptosis. In this study, our aim was to investigate the effects of metformin on morphine-induced neuronal apoptosis and antinociceptive tolerance in diabetic rats. Three days of cumulative dosing were administered to establish morphine tolerance in rats. The antinociceptive effects of metformin (50mg/kg) and test dose of morphine (5mg/kg) were considered at 30-min intervals by thermal antinociceptive tests. To induce diabetic neuropathy, streptozotocin (STZ, 65mg/kg) was injected intraperitoneally. ELISA kits were used to measure caspase-3, bax, and bcl-2 levels from dorsal root ganglion (DRG) tissue. Semi-quantitative scoring system was used to evaluate apoptotic cells with the the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) method. The findings suggest that co-administration of metformin with morphine to diabetic rats showed a significant increase in antinociceptive effect compared to morphine alone. The antinociceptive tests indicated that metformin significantly attenuated morphine antinociceptive tolerance in diabetic rats. In addition, metformin decreased the levels of apoptotic proteins caspase 3 and Bax in DRG neurons, while significantly increased the levels of antiapoptotic Bcl-2. Semi-quantitative scoring showed that metformin provided a significant reduction in apoptotic cell counts in diabetic rats. These data revealed that metformin demonstrated antiapoptotic activity in diabetic rat DRG neurons and attenuated morphine tolerance. The antiapoptotic activity of metformin probably plays a significant role in reducing morphine tolerance.

Ventrolateral periaqueductal gray matter integrative system of defense and antinociception

Defensive responses are neurophysiological processes crucial for survival during threatening situations. Defensive immobility is a common adaptive response, in rodents, elaborated by ventrolateral periaqueductal gray matter (vlPAG) when threat is unavoidable. It is associated with somatosensory and autonomic reactions such as alteration in the sensation of pain and rate of respiration. In this study, defensive immobility was assessed by chemical stimulation of vlPAG with different doses of NMDA (0.1, 0.3, and 0.6 nmol). After elicitation of defensive immobility, antinociceptive and respiratory response tests were also performed. Results revealed that defensive immobility was followed by a decrease in the nociceptive perception. Furthermore, the lowest dose of NMDA induced antinociceptive response without eliciting defensive immobility. During defensive immobility, respiratory responses were also disturbed. Interestingly, respiratory rate was increased and interspersed with prolonged expiratory phase of breathing. These findings suggest that vlPAG integrates three different defensive behavioral responses, contributing to the most effective defensive strategies during threatening situations.

Novel bivalent ligands carrying potential antinociceptive effects by targeting putative mu opioid receptor and chemokine receptor CXCR4 heterodimers

The functional interactions between opioid and chemokine receptors have been implicated in the pathological process of chronic pain. Mounting studies have indicated the possibility that a MOR-CXCR4 heterodimer may be involved in nociception and related pharmacologic effects. Herein we have synthesized a series of bivalent ligands containing both MOR agonist and CXCR4 antagonist pharmacophores with an aim to investigate the functional interactions between these two receptors. In vitro studies demonstrated reasonable recognition of designed ligands at both respective receptors. Further antinociceptive testing in mice revealed compound 1a to be the most promising member of this series. Additional molecular modeling studies corroborated the findings observed. Taken together, we identified the first bivalent ligand 1a showing promising antinociceptive effect by targeting putative MOR-CXCR4 heterodimers, which may serve as a novel chemical probe to further develop more potent bivalent ligands with potential application in analgesic therapies for chronic pain management.

Evaluation of the terpenes β-caryophyllene, α-terpineol, and γ-terpinene in the mouse chronic constriction injury model of neuropathic pain: possible cannabinoid receptor involvement.

Pain is one of the most common reasons to seek medical attention, and chronic pain is a worldwide epidemic. Anecdotal reports suggest cannabis may be an effective analgesic. As cannabis contains the terpenes α-terpineol, β-caryophyllene, and γ-terpinene, we hypothesized these terpenes would produce analgesia in a mouse model of neuropathic pain. We used the chronic constriction injury of the sciatic nerve mouse model, which produces mechanical allodynia, assessed via the von Frey assay, as well as thermal hyperalgesia assessed via the hotplate assay. Compounds were further assessed in tests of locomotor activity, hypothermia, and acute antinociception. Each terpene produced dose-related reversal of mechanical allodynia and thermal hyperalgesia. Thermal hyperalgesia displayed higher sensitivity to the effects of each terpene than mechanical allodynia, and the rank order potency of the terpenes was α-terpineol > β-caryophyllene > γ-terpinene. To examine the involvement of cannabinoid receptors, further tests were conducted in mice lacking either functional cannabinoid type 1 receptors (CB1R (-/-)) or cannabinoid type 2 receptors (CB2R (-/-)). Compared to wild type mice, CB1R (-/-) mice treated with α-terpineol displayed a 2.91-fold decrease in potency to reverse mechanical allodynia; in CB2R (-/-) mice, the potency of α-terpineol was decreased 11.73-fold. The potency of β-caryophyllene to reverse mechanical allodynia decreased 1.80-fold in CB2R (-/-) mice. Each terpene produced a subset of effects in tests of locomotor activity, hypothermia, and acute antinociception. These findings suggest α-terpineol, β-caryophyllene, and γ-terpinene may have differential cannabinoid receptor activity and a pharmacological profile that may yield new efficacious analgesics.

High-performance thin-layer chromatography fingerprinting and anti-inflammatory and antinociceptive activities of Pyracantha coccinea M.Roem.: A laboratory-based study.

This study aimed to investigate the high-performance thin-layer chromatography (HPTLC) fingerprinting and in-vivo anti-inflammatory and antinociceptive activities of different leaf extracts (ethanolic extract, n-hexane, chloroform, and ethyl acetate) of Pyracantha coccinea M.Roem. plant. A total of one hundred and twenty-four Wistar rats for anti-inflammatory and antinociceptive tests (carrageenan and formalin tests, respectively) were treated with two doses of the ethanolic extract (100 and 300 mg/kg), two doses of other plant fractions (30 and 100 mg/kg), Diclofenac (25 mg/kg) as the positive control, and normal saline as the negative control group, by oral gavage route. HPTLC fingerprinting is used for assay of terpenoids, flavonoids, alkaloids, and antioxidant activity. Treatment of the animal with the ethanolic extract at doses of 100 and 300 mg/kg, both ethyl acetate and chloroform fractions at the dose of 30 mg/kg and 100 mg/kg decreased the pain score in the formalin test and paw edema caused by carrageenan relative to control group significantly. Moreover, these extracts reported the highest amounts of flavonoid contents. In conclusion, phytochemicals present in Pyracantha coccinea M.Roem. leaves have anti-inflammatory and antinociceptive activities. Future studies are needed to identify the compounds with the anti-inflammatory and antinociceptive potential present in the plant.

Synthesis, Design, and Biological Evaluation of Novel Diethylphenylcarbamothioylphosphonate

The aim of this work was to synthesize a diethyl phenylcarbamothioyl phosphonate (EThmP) and evaluate its biological activities. ThmP has been prepared with high yields and its conformation was determined. This phosphonothioamidate derivative was characterized by IR, and NMR Spectroscopy (1H, 13C, and 31P). On the component of EThmP, the Hirshfeld surface analysis indicates that the major contributions for the crystal packing are H···H (53.3%), H···O (12.9%) H···S (14.5%), and C···H (17.6%) interactions. An anti-nociceptive test (the formaline test) showed that the EThmP modulates the pain during the early and late phases proved by rat behavior characterized by absence of licking, biting and shaking of the affected paw. The modulation of pain by the EThmP may be due to its anti-inflammatory effect. The Hot Plate test showed that the pretreatment with the EThmP did not modulate the pain nociception induced by maintaining the rat at a fixed temperature of 48°C. The treated rats’ behavior was characterized by elevating, licking the paw, jumping and fleeing. EThmP did not affect the memory capacity and acetylcholinesterase activity. The morbidity of rats was normal with no mortality or sign of toxicity. The in vitro study showed that the EThmP has no antibacterial, antifungal and antioxidant activities. The EThmP has an important dose dependent anti-inflammatory activity.

In vivo analgesic and anti-inflammatory effects of the essential oil from Tanacetum balsamita L.

Tanacetum balsamita locally called Shahesparam is an aromatic plant that grows widely in Azerbaijan Province, Iran. Due to the widespread use of T. balsamita as a pain killer and relief of inflammatory based disorders in Iranian folk medicine and considering the high content of essential oil in T. balsamita aerial parts, we were prompted to investigate the anti-nociceptive and anti-inflammatory properties of T. balsamita essential oil (TBEO) for the first time. The carrageenan-induced Paw Edema was used for inflammation evaluation in rat, and hot-plate method was used for pain assessment in mice. Different doses of TBEO were administered. Morphine and Mefenamic acid were used as the standard drugs in anti-nociceptive and anti-inflammatory evaluation tests, respectively. TBEO (100 mg/kg) showed significantly anti-nociceptive activity in hot-plate test. The anti-inflammatory activity of TBEO was found to be more than mefenamic acid. The studied oil was analyzed by GC and GC-MS. The major component of the oil was characterized as carvone (39.8%) which might be responsible for the observed activities. The results suggested that TBEO possessed biologically active constituents that had significant analgesic and anti-inflammatory effects which support the ethno-medicinal claims of the plant application in the management of pain and inflammation.

μ-opioid/D2 dopamine receptor pharmacophore containing ligands: Synthesis and pharmacological evaluation

Herein, the synthesis and pharmacological evaluation of 13 novel compounds, designed as potential heterobivalent ligands for ?-opioid receptor (MOR) and dopamine D2 receptors (D2DAR), are reported. The compounds consisted of anilido piperidine and N-aryl piperazine moieties, joined by a variable-length methylene linker. The two moieties represent MOR and D2DAR pharmacophores, respectively. The synthesis encompassed four steps, securing the final products in 28?42 % overall yields. The approach has a considerable synthetic potential, providing access to various related structures. Pharmacological tests involved in vitro competitive assay for D2DAR using [3H] spiperon, as a standard radioligand, and in vivo antinociceptive tests for MOR. The measured dopamine affinities were modest to low, while antinociceptive activity was completely absent. Therefore, the compounds of the general structure prepared in this research are unlikely to be useful as opioid?dopamine receptor heterobivalent ligands.

Discriminative Stimulus and Low Abuse Liability Effects of Novel Endomorphin Analogs Suggest a Potential Treatment Indication for Opioid Use Disorder.

Opioid dependence can be difficult to manage using existing pharmacotherapies. A long-acting opioid with low abuse liability that substitutes for a shorter-acting opioid may improve treatment of opioid use disorders (OUDs). We recently characterized an endomorphin (EM) analog (ZH853) that produced a longer duration of antinociception compared with morphine, but did not produce self-administration or several other adverse effects preclinically. Here, we further characterized ZH853 in tests of antinociception, abuse liability, and drug discrimination. A conditioned place preference (CPP) procedure, that included a locomotor activity assessment, was used to test abuse liability in rats. Subsequently, dopamine (DA) cell-somas located in the ventral tegmental area (VTA) from these rats were assessed by size using immunohistochemistry and Stereo Investigator software. A hot-plate antinociception test in male and female mice confirmed central penetration. Morphine-substitution effects of several EM analogs (ZH850, ZH831, and ZH853) were tested in a drug discrimination (DD) procedure in rats. Morphine produced dose-dependent CPP and locomotor sensitization and reduced the size of DA cell somas in VTA, whereas ZH853 did not produce any of these effects relative to control. The antinociceptive effects of ZH853 were μ-receptor selective since β-funaltrexamine antagonized these effects. Rats responded on a morphine-trained lever when injected with ZH831 and ZH853 during DD experiments. The favorable morphine-substitution effects of these EM analogs relative to their low abuse liability indicate promising novel compounds that may improve treatment of OUD. SIGNIFICANCE STATEMENT: In this experiment, we investigated the preclinical effects of novel endomorphin analogs for use as substitution therapies for opioid use disorder, a problem that has contributed to an opioid overdose epidemic. Several endomorphin analogs substituted for morphine without producing adverse effects, including reward behaviors associated with abuse liability. These compounds have the potential to become important additional tools to treat opioid use disorders.

Chemical Constituents, Anti-nociceptive and Anti-inflammatory Activities of Essential Oil of Phyllanthus muellerianus

The aim of the present study was to characterize the chemical composition and to evaluate the anti-inflammatory and anti-nociceptive properties of the essential oil from the leaves of Phyllanthus muellerianus (Kuntze) Exell. The essential oil was hydrodistilled and characterized by gas chromatography-flame ionization detection and gas chromatography coupled with mass spectrometry analyses. The anti-inflammatory activity was evaluated on carrageenan-induced rat paw edema while the anti-nociceptive test was based on hot plate analysis. The hydrodistillation afforded 0.09% (dry weight basis) of pale yellow oil. Thirty-eight compounds representing 94.8% were identified in the oil. The major components of the oil were hexahydrofarnesyl acetone (11.6%), isocaryophyllene (9.8%), and limonene (9.4%). The oils of P. muellerianus displayed anti-nociceptive effect at a rate independent of reaction time and dose ( P < 0.001). The rate of inhibition increased exponentially as the dose increases with optimum activity at 400 mg/kg. The carrageenan-induced edema model revealed the suppression of inflammatory mediators at a very high significant value ( P < 0.001) for all doses, showing activity comparable to a standard drug at 4 hours after carrageenan injection. Collectively, the essential oils depressed the nociceptors and most likely acted as centrally mediated opioid analgesics while the anti-inflammatory mechanisms of the oil might be related to the decrease in the level of iNOS, and cyclo-oxygenase-2 in the edema paw via the suppression of pro-inflammatory cytokines (TNF-α, IL1-β), NO, and PGE2 production. This study confirms the analgesics and inflammatory activities of P. muellerianus.

Anti-inflammatory, antinociceptive and antidiarrhoeal activities of methanol and ethyl acetate extract of Hemigraphis alternata leaves in mice

BackgroundThe study was designed to investigate the qualitative phytochemical constituents and evaluate the anti-inflammatory, anti-nociceptive and anti-diarrhoeal activities of methanol (MHAL) and ethyl acetate (EAHAL) extract of Hemigraphis alternata leaves in Swiss albino mice.MethodsQualitative phytochemical constituents of MHAL and EAHAL were determined by different tests such as Molisch’s test, Fehling test, Mayer’s test, Frothing test, FeCl3 test, Alkali test, Salkowski’s test, Keller-killiani test and CuSO4 test. In addition, Xylene induced-ear edema test and Cotton pellet-induced granuloma formation test had been performed to evaluate the anti-inflammatory activity. Moreover, Formalin-induced paw licking test, Acetic acid-induced writhing tests and Castor oil induced antidiarrheal test had been performed to evaluate the anti-nociceptive and anti-diarrhoeal activities respectively.ResultsThese crude extracts were figured the presence of carbohydrates, flavonoids, tannins, glycosides, triterpenoids, fat and fixed oils. No mortality, behavioral changes or sign of any toxicity were observed up to the dose as high as 4000 mg/kg in mice. During anti-inflammatory test, MHAL 400 mg/kg and EAHAL 200 mg/kg & 400 mg/kg were significantly reduced ear weight differences and granuloma formation in mice. Highest percentage inhibition was offered by EAHAL 400 mg/kg dose (35.15 ± 11.78% and 34.76 ± 11.30%) in both anti-inflammatory tests respectively. In anti-nociceptive experiments, all extracts were significantly reduced paw licking and abdominal writhing of mice. Highest percentage inhibition was offered by EAHAL 400 mg/kg dose (88.21 ± 2.23% and 54.00 ± 2.38%) in both anti-nociceptive tests respectively. In addition, both extracts were showed significant inhibition of percentage of diarrhea in anti-diarrhoeal models except EAHAL 200 mg/kg dose and the apex percentage inhibition is offered by MHAL 400 mg/kg dose (67.73 ± 5.77%).ConclusionThese results confirm that the leaves extract of Hemigraphis alternata are nontoxic and may provide a source of plant compounds with anti-inflammatory, anti-nociceptive and anti-diarrhoeal activities.