Antinociceptive effect of novel trihalomethyl-substituted pyrazoline methyl esters in formalin and hot-plate tests in mice

Catalyst- and base-free visible light-enabled radical relay trihalomethylation/functional group-migration/carbonylation with CX3SO2Cl

Herein, we report a visible light-enabled radical trihalomethylation/cyano-migration/carbonylation cascade reaction of 2-hydroxy-2-hex-5-enenitrile with CX3SO2Cl as the CX3-source (X = F, Cl) to obtain 5-oxo-2-(2,2,2-trihaloethyl)pentanenitrile compounds in the absence of a photocatalyst, transition metal and base. This reaction system is also effective to convert (benzo[d]thiazol-2-yl)-pent-4-enol to the corresponding 4-(benzo[d]thiazol-2-yl)-6,6,6-trihalo-hexanone products. These reactions occur under mild conditions, tolerate a wide range of functional groups, and provide alternative approaches for the 1,2-bifunctionalization reaction of unactivated olefins.

Efficacy of the Multi-Target Compound E153 in Relieving Pain and Pruritus of Different Origins

Itch and pain are closely related but distinct sensations that share largely overlapping mediators and receptors. We hypothesized that the novel, multi-target compound E153 has the potential to attenuate pain and pruritus of different origins. After the evaluation of sigma receptor affinity and pharmacokinetic studies, we tested the compound using different procedures and models of pain and pruritus. Additionally, we used pharmacological tools, such as PRE-084, RAMH, JNJ 5207852, and S1RA, to precisely determine the role of histamine H3 and sigma 1 receptors in the analgesic and antipruritic effects of the compound. In vitro studies revealed that the test compound had potent affinity for sigma 1 and sigma 2 receptors, moderate affinity for opioid kappa receptors, and no affinity for delta or μ receptors. Pharmacokinetic studies showed that after intraperitoneal administration, the compound was present at high concentrations in both the peripheral tissues and the central nervous system. The blood-brain barrier-penetrating properties indicate its ability to act centrally at the levels of the brain and spinal cord. Furthermore, the test compound attenuated different types of pain, including acute, inflammatory, and neuropathic. It also showed a broad spectrum of antipruritic activity, attenuating histamine-dependent and histamine-independent itching. Finally, we proved that antagonism of both sigma 1 and histamine H3 receptors is involved in the analgesic activity of the compound, while the antipruritic effect to a greater extent depends on sigma 1 antagonism.

Tibouchina granulosa Leaves Present Anti-Inflammatory Effect

The ethanol extract (EE) prepared from the leaves of Tibouchina granulosa, and its fraction in ethyl acetate (fEA) were evaluated concerning their capacity to reduce inflammation in different experimental models. fEA was also studied concerning its chemical constituents. EE and fEA were assayed for their anti-inflammatory potential, using formalin-induced licking behavior and carrageenan-induced inflammation into the subcutaneous air pouch (SAP) models. Reduction in polymorphonuclear cells (PMN) activation was performed in freshly isolated PMN. Chromatographic analysis of fEA was performed by HPLC-DAD. Hispiduloside was isolated as the main constituent in fEA, and its quantity was estimated to be 39.3% in fEA. EE (30 mg/kg) significantly reduced the second phase of formalin-induced licking. fEA demonstrated a reduction in leukocyte migration into the SAP. EE and fEA drastically reduced cytokines (TNF-α, IL-1β, and IFN-γ), nitric oxide (NO) production, in vitro PMN migration induced by C5a and IL-8, and TNF-α and IL-1β gene expression. Taken together, our data indicate that either ethanol extract or its fEA fraction from leaves of T. granulosa present an anti-inflammatory effect, contributing to the pharmacological and chemical knowledge of this species and confirming the rationale behind its traditional use.

Ceratonia siliqua leaves ethanol extracts exert anti-nociceptive and anti-inflammatory effects

Background

Ceratonia siliqua L. (Leguminosae) has neuroprotective, mutagenic, hypotensive, anti-bacterial, hypoglycaemic, and anti-inflammatory effects through extracts from its leaves. Therefore, the aim of this study is to assess the anti-nociceptive activity of ethanol extracts of Ceratonia siliqua leaves.

Methods

Ethanol extract of Ceratonia siliqua leaves were studied using well-established animal models of inflammation and pain. A hot plate latency assay (55 °C) was used to assess the analgesic effect of 10, 31.6, 100, and 316 mg/kg doses of ethanol extracts in addition to paw licking time in early and late phase using a formalin-induced paw licking assay test. Paw oedema induction using carrageenan and cotton pellet granuloma assays were used to assess the anti-inflammatory effect of 10, 31.6, 100, and 316 mg/kg doses of ethanol extract.

Results

The ethanol extract of Ceratonia siliqua leaves reduces paw licking time in early and late phase after formalin injection. The same effect was also observed when the hotplate test was performed. Ethanol extract of Ceratonia siliqua leaves caused dose dependent inhibition in paw oedema after the injection of carrageenan and cotton pellet granuloma in mice. These effects were not antagonized when opioid receptors were blocked by naloxone (5 mg/kg). The preliminary phytochemical analysis of the ethanol extract of Ceratonia siliqua leaves showed the presence of tannins, alkaloids, flavonoids and terpenoids.

Conclusion

The present data indicate that ethanol extract of Ceratonia siliqua leaves might possess anti-inflammatory and anti-nociception properties and should be considered for further therapeutic research.

Anti-arthritic and anti-inflammatory effects of Baccharis conferta Kunth in a kaolin/carrageenan-induced monoarthritis model

ETHNOPHARMACOLOGICAL RELEVANCE

Popularly known as "escoba" (broom) or "escobilla china" (Chinese brush), Baccharis conferta Kunth (Asteraceae), is a plant widely used in Mexican folk medicine for alleviating muscular and rheumatic pain. A recent study described that dichloromethane extract as well as fractions and isolated compounds, possess anti-inflammatory activity in TPA-induced acute edema.

AIM OF THE STUDY

Based on the popular medicinal uses of B. conferta as well as previous studies on its anti-inflammatory activity, the aim of this research was to evaluate the anti-arthritic and anti-inflammatory effects of dichloromethane extract, fractions, and compounds from B. conferta in a monoarthritis model induced with kaolin/carrageenan (K/C).

MATERIALS AND METHODS

Aerial parts of B. conferta were collected, dried, and macerated with dichloromethane. The dichloromethane extract (BcD) was separated by open column chromatography to obtain the BcD2 fraction where the diterpene kingidiol (KIN) was isolated and from the BcD3 fraction the flavonoid cirsimaritin (CIR), which are the most active compounds in the TPA model. In addition, the flavonoids acacetin, pectolinaringenin and 6-methoxykaempferide were identified and isolated from the BcD2 fraction. The content of the main compounds was estimated in BcD, BcD2 and BcD3. The anti-arthritic and anti-inflammatory effects of B. conferta were investigated by evaluating ankle joint inflammation, hyperalgesia using the hot plate test, and pro- and anti-inflammatory cytokine levels in the synovial capsule as well as histological changes in ankle joint tissue in a monoarthritis model induced with K/C in Balb/c mice.

RESULTS

Oral administration of BcD2 fraction (25 mg/kg) and KIN (10 mg/kg) reduced the ankle thickness induced by K/C and decreased the levels of TNF-α, IL-1β, IL-6 and IL-17, while BcD2 increased IL-10. In addition, BcD2 and KIN showed significant edema attenuation of the synovial membrane and decreased inflammatory infiltration and cartilage erosion compared to the VEH group. Finally, BcD (50 mg/kg), KIN (10 mg/kg) and CIR (5 mg/kg) decreased hyperalgesia.

CONCLUSIONS

B. conferta constitutes a therapeutic or preventive candidate for osteoarthritis, because of decreased articular inflammation and pain accompanied with the modulation of cytokine concentrations, which confirms the anti-arthritic and anti-inflammatory activities of B. conferta and support its popular use.

Synthesis, Characteristics, and Pharmaceutical Properties of Ibuprofen-Cyclodextrin-PEG Conjugate

The NSAIDs ibuprofen was chemically conjugated to the PEG-graft-β-CyD with an ester bond and its aqueous solubility was clearly improved. The preliminary release profile of ibuprofen in rat gastrointestinal tract contents was performed at 37°C within 12 hours. The polymeric conjugate almost did not release ibuprofen in the contents of stomach, released ibuprofen only 7.4% in the contents of small intestine, and evidently released ibuprofen up to 58.7% in the contents of colon, respectively. These results demonstrated that the polymeric conjugate was site-specifically biodegraded in the rat colonic contents. On the other hand, the xylene-induced ear swelling technique, the hot plate test, and the brewer's yeast-induced hyperthermia model in mice were performed for evaluating the anti-inflammatory, analgesic, and antipyretic activities of the polymeric conjugate, respectively. The results revealed that the polymeric conjugate maintained a long and stable pharmacodynamic efficiency over a period of 24 hours. Hence, the present polymeric ibuprofen-cyclodextrin-PEG conjugate may be of value as an orally administered long-acting prodrug of ibuprofen through colon-targeting delivery.

Design, Synthesis and Biological Activity of New Amides Derived from 3-Benzhydryl and 3-sec-Butyl-2,5-dioxo-pyrrolidin-1-yl-acetic Acid

The aim of this study was to design and synthesize two new series of pyrrolidine-2,5-dione-acetamides with a benzhydryl or sec-butyl group at position 3 as potential anticonvulsants. Their anticonvulsant activity was evaluated in standard animal models of epilepsy: the maximal electroshock (MES), the 6 Hz, and the subcutaneous pentylenetetrazole (scPTZ) tests. The in vivo studies revealed the most potent anticonvulsant activity for 15 (3-(sec-butyl)-1-(2-(4-(3-trifluoromethylphenyl)piperazin-1-yl)-2-oxoethyl)pyrrolidine-2,5-dione), with ED₅₀ values of 80.38 mg/kg (MES) and 108.80 mg/kg (6 Hz). The plausible mechanism of action was assessed in in vitro binding assays, in which 15 interacted effectively with voltage-gated sodium (site 2) and L-type calcium channels at a concentration of 100 μM. Subsequently, the antinociceptive activity of compounds 7 and 15 was observed in the hot plate test of acute pain. Moreover, compounds 7, 11 and 15 demonstrated an analgesic effect in the formalin test of tonic pain. The hepatotoxic properties of the most effective compounds (7, 11 and 15) in HepG2 cells were also investigated.

Intracerebroventricular Delivery of Human Umbilical Cord Mesenchymal Stem Cells as a Promising Therapy for Repairing the Spinal Cord Injury Induced by Kainic Acid

Spinal cord injury (SCI) is a common pathological condition that leads to permanent or temporal loss of motor and autonomic functions. Kainic acid (KA), an agonist of kainate receptors, a type of ionotropic glutamate receptor, is widely used to induce experimental neurodegeneration models of CNS. Mesenchymal Stem Cells (MSC) therapy applied at the injured nervous tissue have emerged as a promising therapeutic treatment. Here we used a validated SCI experimental model in which an intraparenchymal injection of KA into the C5 segment of rat spinal cord induced an excitotoxic lesion. Three days later, experimental animals were treated with an intracerebroventricular injection of human umbilical cord (hUC) MSC whereas control group only received saline solution. Sensory and motor skills as well as neuronal and glial reaction of both groups were recorded. Differences in motor behavior, neuronal counting and glial responses were observed between hUC-MSC-treated and untreated rats. According to the obtained results, we suggest that hUC-MSC therapy delivered into the fourth ventricle using the intracerebroventricular via can exert a neuroprotective or neurorestorative effect on KA-injected animals.

Anti-Inflammatory and Antinociceptive Activity of Pollen Extract Collected by Stingless Bee Melipona fasciculata

The stingless bee, Melipona fasciculata Smith (Apidae, Meliponini), is a native species from Brazil. Their products have high biotechnological potential, however there are no studies about the biological activities of pollen collected by M. fasciculata. In this context, the present study investigated the chemical composition, anti-oxidant, anti-inflammatory, and analgesic activities of hydroethanolic pollen extracts collected by M. fasciculata in three cities in Maranhão State, Brazil. We verified the antioxidant activity of the extracts and inhibitory activity against the cyclooxygenase enzyme using in vitro assays and in allowed to select the extract with higher efficiency to be used on in vivo assays. In these trials, the selected extract showed high anti-inflammatory activity as well as nociceptive effects at central and peripheral level, suggesting that this extract acts on inhibition of histamine release and decreased synthesis of prostaglandins and the in-silico study suggested that polyphenols and acids fatty acids in the extract may be associated with these activities. The results of the present study report the high biological potential of pollen extract and we conclude that the pollen collected by M. fasciculata can be considered as the object of research for new pharmacological alternatives.

Antinociceptive and antioxidant effects of extract enriched with active indole alkaloids from leaves of Tabernaemontana catharinensis A. DC

ETHNOPHARMACOLOGICAL RELEVANCE

Ethnopharmacological knowledge is important for the identification of active compounds from natural products. Pain may have different aetiologies with complex mechanisms. Tabernaemontana catharinensis A. DC. is well known for indole alkaloids, being used empirically in folk medicine, with antimicrobial and anti-inflammatory as well as antiofidic actions among others.

AIM OF THE STUDY

This work aims to evaluate the antinociceptive and antioxidant effect in mice of the alkaloids extract from leaves of Tabernaemontana catharinensis A. DC. (AITc).

MATERIALS AND METHODS

The AITc was produced by ultrasound and acid-base extraction, and the chemical composition was evaluated by high resolution mass spectrometry. Male mice (Mus musculus), Swiss, were used for in vivo tests. The AITc was administrated at doses of 1.0, 5.0, and 10.0 mg/kg in acetic acid model, formalin, tail-immersion, hot plate, and open field tests, and compared to saline, morphine, or diazepam controls, depending on the test. The toxicological, biochemical, haemogram and antioxidant effect were evaluated in mouse organs such as liver, brain, kidneys, spleen and stomach.

RESULTS

In total, 10 compounds were identified in the AITc, being from the indole alkaloids from the ibogan and corynanthean classes. The extract in doses ranging from 5.0 to 10.0 mg/kg showed an antinociceptive effect for acetic acid, inhibiting by 47.7% and 61.6%. In the same line, reductions of 47.1% (first phase) and 43.6% (second phase) were observed for the 5.0 mg/kg dose in the formalin test. However, tail-immersion and hot plate tests did not show considerable modifications in the latency period, while in the open field test there was an inhibition of only 5.1%. It was observed no differences in NO levels and total antioxidant status of the mice in any of the studie tissues.

CONCLUSIONS

The results justify the use of this plant in traditional medicine. in vivo tests indicate that these compounds possess central and peripheral mechanisms of action. This is study that reports the nociceptive action of these alkaloids, also including toxicity tests, which are intended to guarantee the safety of use of extracts of this plant.

Methanol extract of Cola nitida ameliorates inflammation and nociception in experimental animals

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Methanol extract Cola nitida possesses analgesic properties in mice.

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Methanol extract of Cola nitida showed anti-inflammatory activity.

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Methanol extract of cola nitida mediates its nociceptive action through cholinergic pathway.

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Opioid and beta adrenergic pathways do not mediate the analgesic potential of Cola nitida.

Methanol extract of Cola nitida (MECN) was evaluated for its anti-inflammatory and analgesic activities using rats and mice. Inflammatory activity of MECN was assessed by carrageenan-induced paw oedema while analgesic activity was evaluated by acetic acid –induced writhing and formalin paw lick test. Histological analyses of the paws were also carried out. There was evaluation of the mechanism(s) of action of MECN using naloxone, a blocker of opioid receptors; atropine, blocker of muscarinic receptors; and propranolol, blocker of beta adrenergic receptors. Findings from the study revealed that MECN has both anti-inflammatory and analgesic properties. These properties were found to be dose dependent with 200 mg/kg of MECN discovered to be the most potent dose. 200 mg/kg was able to cause statistically significant reduction in paw size (p < 0.001) when compared with the carrageenan group. Histological analysis revealed that rats treated with 200 mg/kg of MECN showed no inflammatory cells in the left paw compared to other groups treated with carrageenan. In the formalin test, the number of paw licking was significantly reduced by MECN at 50 mg/kg, 100 mg/kg and 200 mg/kg in both neurogenic and inflammatory pain responses (p < 0.001) even as 200 mg/kg showed the highest percentage inhibition of 98.17% while 100 mg/kg of aspirin showed percentage inhibition of 93.66%. In acetic acid-induced writhing test, 50 mg/kg, 100 mg/kg and 200 mg/kg of MECN produced significant inhibition of writhes when compared with control as highest inhibition is observed in mice that received 200 mg/kg which is similar to aspirin. Administration of propranolol and naloxone was unable to reverse the analgesic function of MECN. However, atropine administration blocked the analgesic function of MECN. This shows that MECN exhibits its analgesic property through cholinergic pathway and not opioid and adrenergic pathways. Phytochemical screening revealed that MECN contains flavonoids, steroids, saponins, tannins, anthraquinines, terpenoids, and alkanoids. These phytochemical contents may thus be responsible for its analgesic and anti-inflammatory properties.

Chronic Monosodium Glutamate Administration Induced Hyperalgesia in Mice

Monosodium glutamate (MSG) is a widely used food additive. Although it is generally considered safe, some questions regarding the impact of its use on general health have arisen. Several reports correlate MSG consumption with a series of unwanted reactions, including headaches and mechanical sensitivity in pericranial muscles. Endogenous glutamate plays a significant role in nociceptive processing, this neurotransmitter being associated with hyperalgesia and central sensitization. One of the mechanisms underlying these phenomena is the stimulation of Ca2+/calmodulin sensitive nitric oxide synthase, and a subsequent increase in nitric oxide production. This molecule is a key player in nociceptive processing, with implications in acute and chronic pain states. Our purpose was to investigate the effect of this food additive on the nociceptive threshold when given orally to mice. Hot-plate and formalin tests were used to assess nociceptive behaviour. We also tried to determine if a correlation between chronic administration of MSG and variations in central nitric oxide (NO) concentration could be established. We found that a dose of 300 mg/kg MSG given for 21 days reduces the pain threshold and is associated with a significant increase in brain NO level. The implications of these findings on food additive-drug interaction, and on pain perception in healthy humans, as well as in those suffering from affections involving chronic pain, are still to be investigated.

Antihyperalgesic effect of [(±)-(2,4,6-cis)-4-chloro-6-(naphthalen-1-yl)-tetrahydro-2H-pyran-2-yl]methanol: participation of the NO/cGMP/KATP pathway and κ-opioid receptor

The present study used behavioral analyses to investigate the involvement of the NO/cGMP/KATP pathway, serotoninergic, and opioid systems in the antinociceptive action of [(±)-(2,4,6-cis)-4-chloro-6-(naphthalen-1-yl)-tetrahydro-2H-pyran-2-yl]methanol (CTHP) in mice. Oral administration of CTHP (1, 5, 10, and 30 mg/kg) exerted effects at higher doses in chemical models of nociception (the acetic acid writhing and formalin tests) as well as a thermal model (the tail-flick test). It was also found that pretreatment with L-N-nitroarginine methyl ester (nonselective nitric oxide synthase inhibitor), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (selective inhibitor of nitric oxide-sensitive guanosyl cyclase), glibenclamide (selective ATP-sensitive K channel blocker), naloxone (nonselective opioid receptor blocker), and nor-binaltorphimine (selective κ-opioid receptor blocker), but not methylnaltrexone (peripheral μ-opioid receptor blocker) or naltrindole (selective δ-opioid receptor blocker), reversed the antinociceptive effect of CTHP. In addition, CTHP induced the development of tolerance in the tail-flick test: the tolerance appeared later compared with morphine, and was only observed with a higher dose. Taken together, the present study showed that the systemic administration of CTHP reduced pain induced by chemical and thermal stimuli. We also suggest that the possible mechanisms include the involvement of the NO/cGMP/KATP pathway and the κ-opioid receptor.

Effects of 1,3,5-triphenyl-4,5-dihydro-1H-pyrazole derivatives on cell-cycle and apoptosis in human acute leukemia cell lines

Pyrazoline is an important 5-membered nitrogen heterocycle that has been extensively researched. Ten derivatives were synthesized and tested for antileukemic effects on 2 human acute leukemia cell lines, K562 and Jurkat. The most cytotoxic of these derivatives, compound 21, was chosen for investigation of cytotoxicity mechanisms. The results obtained with selectivity calculations revealed that compound 21 is more selective for acute leukemia (K562 and Jurkat cell lines) than for other tumor cell lines. Moreover, compound 21 was not cytotoxic to normal cell lines, indicating a potential use in clinical tests. Compound 21 caused a significant cell cycle arrest in the S-phase in Jurkat cells and increased the proportion of cells in the sub G0/G1 phase in both cell lines. Cells treated with compound 21 demonstrated morphological changes characteristic of apoptosis in the EB/AO assay, confirmed by externalization of phosphatidylserine by the annexin V – fluorescein isothiocyanate method and by DNA fragmentation. An investigation of cytotoxicity mechanisms suggests the involvement of an intrinsic apoptosis pathway due to mitochondrial damage and an increase in the ratio of mitochondrial Bax/Bcl2. Pyrazoline 21 obeyed Lipinski’s “rule of five” for drug-likeness. Based on these preliminary results, the antileukemic activity of compound 21 makes it a potential anticancer agent.

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

ETHNOPHARMACOLOGICAL RELEVANCE

The medicinal plant generally known as monkey's comb (Amphilophium crucigerum) has been popularly described for the treatment of neuropathic and inflammatory pain, specially seeds preparations.

AIM OF THE STUDY

The goal of the present study was to evaluate the antinociceptive effect of the crude extract (Crd) and dichloromethane fraction (Dcm) of A. crucigerum seeds, and investigate the involvement of transient receptor potential vanilloid 1 (TRPV1) receptor in this effect.

MATERIALS AND METHODS

Male Swiss mice were used in this study. The effects of Crd and Dcm was tested on capsaicin-induced Ca²⁺ influx or the specific binding of [³H]-resiniferatoxin. Moreover, after treatment with Crd or Dcm, animals were exposed to acute pain (hot water tail-flick and capsaicin intraplantar test) or chronic pain models (injection of complete Freund's adjuvant or partial ligation of the sciatic nerve). Acute adverse effects were also noted: locomotor activity, corporal temperature, hepatic or renal damage, gastrointestinal transit alteration, and ulcerogenic activity.

RESULTS

The oral administration of Crd or Dcm resulted in an antinociceptive effect in the hot water tail-flick (48°C) and capsaicin intraplantar tests. Furthermore, these preparations exhibited antinociceptive and anti-inflammatory effects in a chronic inflammatory pain model, and antinociceptive effects in a neuropathic pain model. Moreover, Crd and Dcm reduced capsaicin-induced Ca²⁺ influx and diminished the [³H]-resiniferatoxin specific binding to spinal cord membranes. Acute adverse events were not found with Crd or Dcm administration.

CONCLUSION

In conclusion, our results support the analgesic effect of A. crucigerum and suggest the presence of compounds that may act as TRPV1 antagonists.

Cholinergic activation affects the acute and chronic antinociceptive effects of morphine

Current studies indicate that the cholinergic and opioid systems interact to modulate pain. In the present work, we investigated the influence of the cholinesterase inhibitors, donepezil (0.5; 1 or 3mg/kg, i.p.) and rivastigmine (0.03; 0.5 or 1mg/kg, i.p.), on the acute antinociceptive effects of morphine (5mg/kg, i.p.) in the hot plate test in mice. Herein, both inhibitors were found to enhance and prolong the analgesic effects of morphine without affecting latencies themselves. In an extension of this work, we determined which cholinergic receptors subtype mediates the enhancement of analgesic effects of morphine, following inhibition of cholinesterases. In this part of the study, scopolamine (0.5mg/kg, i.p.), a muscarinic cholinergic receptors antagonist, but not mecamylamine (3mg/kg, i.p.), a nicotinic cholinergic receptors antagonist, reversed the enhancing effects of donepezil (3mg/kg, i.p.) and rivastigmine (1mg/kg, i.p.) on the morphine antinociception. Moreover, both cholinesterase inhibitors attenuated the development of tolerance to the antinociceptive effects of morphine. In contrast, acute administration of donepezil (3mg/kg, i.p.) or rivastigmine (1mg/kg, i.p.) on the day of expression of tolerance, had no effect on the already developed morphine tolerance. What is more, in both set of experiments, rivastigmine was slightly more potent than donepezil due to the broader inhibitory spectrum of this drug on acetylcholine degradation. Thus, our results suggest that the cholinesterase inhibitors, donepezil and rivastigmine, may be administered with morphine in order to enhance the latter's analgesic effects for the treatment of acute and chronic pain.

Tabernaemontana catharinensis ethyl acetate fraction presents antinociceptive activity without causing toxicological effects in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Tabernaemontana catharinensis (Apocynaceae) is a medicinal plant used for the treatment of painful and inflammatory disorders. Here, we investigated the antinociceptive potential of the ethyl acetate fraction (Eta) from T. catharinensis leaves and assessed its toxic effects in mice to validate its popular use.

MATERIALS AND METHODS

Adult male Swiss mice (30-35g) were used. The Eta antinociceptive effect (200-800mg/kg, oral route (p.o.)) was evaluated in the acetic acid, formalin, capsaicin and tail-immersion tests. Adverse effects were analyzed using rotarod and open-field tests, body temperature, biochemical analysis and gastric lesions assessment. To evaluate the acute (OECD 423) or sub-acute (OECD 407) toxicity of the Eta, it was administered orally at a single (2000mg/kg) or repeated doses (100-400mg/kg/day for 28 days), respectively. Mortality, behavioral changes, biochemical and hematological parameters were evaluated. The Eta effect on cellular viability also was evaluated.

RESULTS

Eta (200-800mg/kg) inhibited the nociception caused by acetic acid (93.9±1.5%), formalin (86.2±10.8%) or capsaicin (75.4±3.3%) without inducing gastric lesions. Moreover, Eta neither altered the body temperature, biochemical parameters, nor forced or spontaneous locomotor activity of mice. The acute administration of the Eta (2000mg/kg) promoted a decrease in blood glucose levels and alanine aminotransferase activity. In the sub-acute toxicity study, Eta increased the aspartate aminotransferase activity (400mg/kg) and platelet distribution width (200mg/kg). Furthermore, Eta did not alter the cellular viability in cortical slices.

CONCLUSIONS

Eta presents antinociceptive effects and mild toxicity in mice. These results support its traditional use as a potential analgesic.

Antinociceptive and anti-inflammatory effect of the Scutia buxifolia Reissek stem barks extract

BACKGROUND

Scutia buxifolia (Rhamnaceae) has been extensively studied for its phenolics groups, which are able to capture free radicals; being therefore, considered promising as an antioxidant in preventing diseases resulting from oxidative stress.

HYPOTHESIS

Scutia buxifolia extract (SBE) presents antinociceptive and anti-inflammatory effect in mice.

STUDY DESIGN

SBE (400-800mg/kg) was tested in different pain models to investigate its antinociceptive and anti-inflammatory action.

METHODS

It was carried out the abdominal writhing test, capsaicin test, thermal hyperalgesia and incisional pain. The inflamed tissue by carrageenan was used for the analysis of interleukins (IL), interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), c-reactive protein (CRP), nitrite and nitrate (NOx) determination and myeloperoxidase (MPO) activity. Furthermore, we evaluate the possible action mechanism of SBE using naloxone in capsaicin test.

RESULTS

SBE prevented the nociception caused by acetic acid, formalin and capsaicin test. However, neither the SBE prevented the thermal hyperalgesia in hot-plate test, nor the naloxone reversed the SBE antinociceptive effect in capsaicin test. Furthermore, the administration of SBE prevented significantly the increase of MPO activity, the NOx content, and the levels of IL-1, IL-6, TNF-α, INF-γ and CRP and was able to increase the IL-10 levels after the inflammation induced by carrageenan in mice. In addition, SBE prevented mechanical hyperalgesia in a postoperative pain model.

CONCLUSION

The SBE presents great antinociceptive and anti-inflammatory activity in mice but this effect not seem to have its action mechanism like opioids. It is possible that its antinociceptive effects are associated with levels decrease of inflammatory mediators.

Strong and Long-Lasting Antinociceptive and Anti-inflammatory Conjugate of Naturally Occurring Oleanolic Acid and Aspirin

The conjugate 8 was obtained as a result of condensation of 3-hydroxyiminooleanolic acid morfolide (7) and aspirin in dioxane. Analgesic effect of OAO-ASA (8) for the range of doses 0.3–300.0 mg/kg (p.o.) was performed in mice using a hot-plate test. Anti-inflammatory activity was assessed on carrageenan-induced paw edema in rats for the same range of doses. The conjugate OAO-ASA (8) did not significantly change locomotor activity of mice, therefore sedative properties of the compound should be excluded. The compound 8 proved a simple, proportional, dose-dependent analgesic action and expressed strong anti-inflammatory activity showing a reversed U-shaped, dose-dependent relation with its maximum at 30.0 mg/kg. After its combined administration with morphine (MF, 5.0 mg/kg, s.c.) the lowering of antinociceptive activity was found; however, the interaction with naloxone (NL, 3.0 mg/kg, s.c.) did not affect the antinociceptive effect of OAO-ASA (8), therefore its opioid mechanism of action should be rather excluded. After combined administration with acetylsalicylic acid (ASA, 300.0 mg/kg, p.o.) in hot-plate test, the examined compound 8 enhanced the antinociceptive activity in significant way. It also shows that rather the whole molecule is responsible for the antinociceptive and anti-inflammatory effect of the tested compound 8, however, it cannot be excluded that the summarizing effect is produced by ASA released from the compound 8 and the rest of triterpene derivative. The occurrence of tolerance for triterpenic derivative 8 was not observed, since the analgesic and anti-inflammatory effects after chronic administration of the conjugate OAO-ASA (8) was on the same level as after its single treatment. It seemed that the anti-inflammatory mechanism of action of OAO-ASA (8) is not simple, even its chronic administration lowered both blood concentration of IL-6 and mRNA IL-6 expression. However, the effects of the conjugate OAO-ASA (8) on TNF-α level and mRNA expression were opposite. Moreover, compound 8 did not change unequivocally mRNA TLR1, and TLR3 expression. Concluding, the obtained results regarding the antinociceptive and anti-inflammatory activity of new conjugate of oleanolic acid oxime and acetylsalicylic acid (OAO-ASA 8) are very interesting, but for explanation of its mechanism of action, more detailed studies are necessary.

Evaluation of anti-inflammatory and analgesic activities of extracts from herb of Chelidonium majus L

The aim of the study was to evaluate analgesic activity ("hot plate" test), anti-inflammatory activity (carrageenan-induced paw edema) and locomotor activity in rats under the influence of three fractions of Chelidonium majus herb extract: full water extract (FWE), protein enriched fraction (PEF), and non-protein fraction (NPF). Effects of the fractions on the level of chosen cytokines and their mRNA levels were also assessed using lipopolysaccharide (LPS) administration as a proinflammatory cue. All fractions and diclofenac did not affect the locomotor activity of rats in comparison with the control group. FWE and PEF three hours after administration showed statistically significant analgesic activities comparable to morphine (p < 0.05). A slight reduction in rat paw edema was observed after three (comparable with diclofenac) and six hours in the NPF group. FWE revealed a statistically significant pro-inflammatory effect after three hours in comparison with the control group. Peripheral IL-1 and IL-4 cytokine concentrations were reduced under FWE and NPF, PEF fractions. The combination of FWE, PEF and NPF together with LPS showed only the effects of LPS. We suggest that protein enriched fraction (PEF) produced centrally mediated (morphine-like) analgesic action, whereas the anti-inflammatory potential was shown only after LPS-induced inflammation. The precise mechanisms involved in the production of anti-nociceptive and anti-inflammatory responses of studied fractions are not completely understood, but they may be caused rather by the presence of protein more than alkaloids-enriched fraction. This fraction of the extract could be used as an alternative therapy for the prevention of inflammatory-related diseases in the future, but further studies are needed.

Novel ibuprofenate- and docusate-based ionic liquids: emergence of antimicrobial activity

Six new ionic-liquid-based active pharmaceutical ingredients (IL-APIs) were prepared and their molecular structures characterized.

Functional and histopathological changes induced by intraparenchymal injection of kainic acid in the rat cervical spinal cord

Kainic acid (KA) is an analog of the neurotransmitter glutamate and is widely used as an excitotoxic agent to lesion spinal cord networks, thus, providing an interesting model to learn basic mechanisms of spinal cord injury. The present work was aimed to evaluate motor and sensory performance of rats and analyze morphometric parameters of spinal cord neurons after KA injection. Animals were injected either with 0.75, 1 or 1.25 mM of KA at the C5 segment of the cervical spinal cord. Motor and sensory performance of the rats were evaluate at day 0 (before injection) and at days 1, 2, 3 and 7 post-injection (pi) and compared with those of saline-treated and non-operated animals. Animals were sacrificed at each time point for morphometric and histopathological analysis and compared among groups. All KA-treated animals showed a significant impairment at the motor and sensory tests for the ipsilateral forelimb in a concentration-dependent manner in comparison to saline-treated and non-operated animals. Neuronal cell count showed a significant loss of neurons at C4, C5 and C6 cervical segments when compared with those of saline-treated and non-operated animals. The contralateral side of the cervical segments in KA-treated rats remained unchanged. Some improvement at the motor and sensory tests was observed in animals injected with 0.75 and 1mM KA. Moreover, a mild increase in the neuronal count of the damaged segments was also recorded. The improvement recorded in the motor and sensory tests by day 7 pi may be a consequence of a neuron repairing mechanism triggered soon after the KA excitotoxic effect.

Antinociceptive, anti-inflammatory and smooth muscle relaxant activities of the pyrrolo[3,4-d]pyridazinone derivatives: Possible mechanisms of action

The aim of this study was to evaluate the analgesic as well as anti-inflammatory activities of the new pyrrolo[3,4-d]pyridazinone derivatives. Moreover, the present study attempted to assess some of the mechanisms involved in the pharmacological activity of these compounds. In the previous studies it was shown that these compounds were highly active in the phenylbenzoquinone-induced 'writhing syndrome' test and had much lower activity in the hot plate, which indicates that mainly peripheral mechanisms of analgesia are involved in their effects. In these extended studies the analgesic activity of two tested compounds (4c, 4f) was confirmed in some animal models of pain. The studied compounds showed a significant and dose-related antinociceptive effect in the models of pain induced by formalin, capsaicin and glutamic acid. Both compounds decreased the edema formation and one of them (4c) attenuated mechanical hyperalgesia in carrageenan-induced paw inflammation in rats. Furthermore, both compounds inhibited cell migration, plasma exudation and nociceptive reaction in zymosan A-induced mouse peritonitis. In the subsequent studies, including experiments on isolated organs (ileum, trachea, aorta), radioligand assays and biochemical tests, it was demonstrated that analgesic and anti-inflammatory effects of the investigated structures are largely due to their competitive antagonism for histamine H1 receptor. The influence on the level of cAMP in inflammatory cells (shown in RAW 264.7 macrophages) and subsequent inhibition of cytokine (TNFα, IL-1β) release can also be one of the important mechanisms of their action. Moreover some additional mechanisms may also be involved in the eventual analgesic effect of tested pyrrolo[3,4-d]pyridazinone derivatives.

Involvement of the NO/cGMP/KATP pathway in the antinociceptive effect of the new pyrazole 5-(1-(3-fluorophenyl)-1H-pyrazol-4-yl)-2H-tetrazole (LQFM-021)

The pyrazol compounds are known to possess antipyretic, analgesic and anti-inflammatory activities. This study was conducted to investigate the peripheral antinociceptive effect of the pyrazole compound 5-(1-(3-Fluorophenyl)-1H-pyrazol-4-yl)-2H-tetrazole (LQFM-021) and involvement of opioid receptors and of the NO/cGMP/K(ATP) pathway. The oral treatments in mice with LQFM-021 (17, 75 or 300 mg/kg) decreased the number of writhing. In the formalin test, the treatments with LQFM-021 at doses of 15, 30 and 60 mg/kg reduced the licking time at both neurogenic and inflammatory phases of this test. The treatment of the animals with LQFM-021 (30 mg/kg) did not have antinociceptive effects in the tail-flick and hot plate tests. Furthermore, pre-treatment with naloxone (3 mg/kg i.p.), L-name (10 mg/kg i.p.), ODQ (10 mg/kg i.p.) or glibenclamide (3 mg/kg i.p.) antagonized the antinociceptive effect of LQFM-021 in both phases of the formalin test. In addition, it was also demonstrated that the treatments of mice with LQFM-021(15, 30 and 60 mg/kg) did not compromise the motor activity of the animals in the chimney test. Only the highest dose used in the antinociceptive study promoted changes in the open field test and pentobarbital-induced sleep test, thus ruling out possible false positive effects on nociception tests. Our data suggest that the peripheral antinociception effects of the LQFM-021 were mediated through the peripheral opioid receptors with activation of the NO/cGMP/KATP pathway.

Reaction of cyclopropenes with a trichloromethyl radical: unprecedented ring-opening reaction of cyclopropanes with migration

The triethylborane-mediated direct addition of chloroform to cyclopropenes afforded trichloromethylcyclopropanes. In contrast, the use of dimethylzinc gave the unconjugated diene via ring-opening reactions.

A novel, potent, oral active and safe antinociceptive pyrazole targeting kappa opioid receptors

Pyrazole compounds are an intriguing class of compounds with potential analgesic activity; however, their mechanism of action remains unknown. Thus, the goal of this study was to explore the antinociceptive potential, safety and mechanism of action of novel 1-pyrazole methyl ester derivatives, which were designed by molecular simplification, using in vivo and in vitro methods in mice. First, tree 1-pyrazole methyl ester derivatives (DMPE, MPFE, and MPCIE) were tested in the capsaicin test and all presented antinociceptive effect; however the MPClE (methyl 5-trichloromethyl-3-methyl-1H-pyrazole-1-carboxylate) was the most effective. Thus, we selected this compound to assess the effects and mechanisms in subsequent pain models. MPCIE produced antinociception when administered by oral, intraperitoneal, intrathecal and intraplantar routes and was effective in the capsaicin and the acetic acid-induced nociception tests. Moreover, this compound reduced the hyperalgesia in diverse clinically-relevant pain models, including postoperative, inflammatory, and neuropathic nociception in mice. The antinociception produced by orally administered MPClE was mediated by κ-opioid receptors, since these effects were prevented by systemically pre-treatment with naloxone and the κ-opioid receptor antagonist nor-binaltorphimine. Moreover, MPCIE prevented binding of the κ-opioid ligand [(3)H]-CI-977 in vitro (IC₅₀ of 0.68 (0.32-1.4) μM), but not the TRPV1 ([(3)H]-resiniferatoxin) or the α₂-adrenoreceptor ([(3)H]-idazoxan) binding. Regarding the drug-induced side effects, oral administration of MPClE did not produce sedation, constipation or motor impairment at its active dose. In addition, MPCIE was readily absorbed after oral administration. Taken together, these results demonstrate that MPClE is a novel, potent, orally active and safe analgesic drug that targets κ-opioid receptors.

Mechanisms involved in the nociception triggered by the venom of the armed spider Phoneutria nigriventer

BACKGROUND

The frequency of accidental spider bites in Brazil is growing, and poisoning due to bites from the spider genus Phoneutria nigriventer is the second most frequent source of such accidents. Intense local pain is the major symptom reported after bites of P. nigriventer, although the mechanisms involved are still poorly understood. Therefore, the aim of this study was to identify the mechanisms involved in nociception triggered by the venom of Phoneutria nigriventer (PNV).

METHODOLOGY/PRINCIPAL FINDINGS

Twenty microliters of PNV or PBS was injected into the mouse paw (intraplantar, i.pl.). The time spent licking the injected paw was considered indicative of the level of nociception. I.pl. injection of PNV produced spontaneous nociception, which was reduced by arachnid antivenin (ArAv), local anaesthetics, opioids, acetaminophen and dipyrone, but not indomethacin. Boiling or dialysing the venom reduced the nociception induced by the venom. PNV-induced nociception is not dependent on glutamate or histamine receptors or on mast cell degranulation, but it is mediated by the stimulation of sensory fibres that contain serotonin 4 (5-HT4) and vanilloid receptors (TRPV1). We detected a kallikrein-like kinin-generating enzyme activity in tissue treated with PNV, which also contributes to nociception. Inhibition of enzymatic activity or administration of a receptor antagonist for kinin B2 was able to inhibit the nociception induced by PNV. PNV nociception was also reduced by the blockade of tetrodotoxin-sensitive Na(+) channels, acid-sensitive ion channels (ASIC) and TRPV1 receptors.

CONCLUSION/SIGNIFICANCE

Results suggest that both low- and high-molecular-weight toxins of PNV produce spontaneous nociception through direct or indirect action of kinin B2, TRPV1, 5-HT4 or ASIC receptors and voltage-dependent sodium channels present in sensory neurons but not in mast cells. Understanding the mechanisms involved in nociception caused by PNV are of interest not only for better treating poisoning by P. nigriventer but also appreciating the diversity of targets triggered by PNV toxins.

A thermoplastic elastomer patch matrix for traditional Chinese medicine: design and evaluation

OBJECTIVE

To design and evaluate a novel pressure sensitive adhesive (PSA) patch containing traditional Chinese medicine (TCM) using styrene-isoprene-styrene (SIS) copolymer.

METHOD

A mixture D-optimal design with ternary response surface diagram was employed in the optimization process. The proportions of SIS copolymer, tackifying resin and plasticizer were selected as the independent variables while tack force, peel strength of the patch and skin penetrability of methyl salicylate were selected as the dependent variables. The optimized patch was then evaluated including in vivo absorption, pharmacological activities and skin irritation, by comparing with a commercial patch based on natural rubber.

RESULTS

The optimized patch, which comprised 30.0% SIS copolymer, 26.6% tackifying resin and 43.4% plasticizer, was superior to commercial patch in skin permeation, pharmacological activities and skin biocompatibility.

CONCLUSION

SIS copolymer was a suitable substitute to natural rubber in producing patches containing TCM formula.