Peripheral and central antinociceptive effects of the butanolic fraction of Byrsonima verbascifolia leaves on nociception-induced models in mice

Antinociceptive activity of the Caesalpinia eriostachys Benth. ethanolic extract, fractions, and isolated compounds in mice

Caesalpinia eriostachys Benth. (CE) is native to the Mexico and multiple effects have been observed from several plants belonging to the same family. CE was subjected to extraction with 95% ethanol, and the components were isolated through column chromatography. The structure of the compound was elucidated based on nuclear magnetic resonance (NMR) spectral data, electron ionization-mass (EI-MS) spectroscopy, and liquid chromatography-mass (LC-MS) spectroscopy. In vivo antinociceptive studies were conducted using writhing, 5% formalin, tail-flick, hot-plate, and von Frey filament tests. The ethanolic extract showed a significant effect in the acetic acid-induced pain model and nociceptive behavior in the formalin model (second phase). In hot-plate test and tail-flick test, the results showed no difference compared to the control group. The results suggest that the ethanolic extract may act peripherally to reduce pain. In the streptozotocin (STZ)-induced pain model, the ethanolic extract showed significant effect in the von Frey test model. The n-Hex (Hexane) and MC (Methylene chloride) fractions and isolated compounds, ellagic acid and agathisflavone, showed increased effect. Based on these results, we confirmed that the CE ethanolic extract and their compounds, ellagic acid and agathisflavone, have antinociceptive effect on diabetes mellitus-induced pain. Furthermore, the results of this study might be valuable for identifying compounds with antinociceptive activity from natural products.

In vivo anti-inflammatory and antinociceptive effects, and in vitro antioxidant, antiglycant and anti-neuroinflammatory actions of Syzygium malaccense

Syzygium malaccense is popularly used to treat inflammation and pain-related ailments. The species was assessed regarding its antioxidant, antiglycant, anti-inflammatory, including anti-neuroinflammatory, and antinociceptive activities. Different models were employed to measure S. malaccense extract (ESM) antioxidant activity. The antiglycant activity was determined using the glucose-induced protein glycation model. LPS-induced neuroinflammation on murine BV-2 microglial cell line was used for anti-neuroinflammatory activity evaluation. The croton oil-induced ear edema test was accomplished to evaluate the in vivo anti-inflammatory activity. Acetic acid-induced writhing together with formalin-induced paw licking assays were performed to evaluate the antinociceptive potential. Finally, the chemical characterization was accomplished by a UHPLC-MS analysis. ESM presented relevant antioxidant and antiglycant activity. NO production by BV-2 cells was reduced, indicating the relevant neuroprotective activity. ESM significantly decreased the mice ear edema induced by croton oil and the nociceptive stimulus induced by acetic acid and formalin by central and peripheral mechanisms. The flavonoids myricitrin, myricetin and quercetin were identified and, as far as we know, the alkaloid reserpine was reported in the species for the first time. The antioxidant and antiglycant potential of ESM, may be related to the in vivo anti-inflammatory and antinociceptive effects, and to the in vitro neuroinflammation inhibition.

Anti-inflammatory and antinociceptive activity of Siparuna guianensis Aublet, an amazonian plant traditionally used by indigenous communities

ETHNOPHARMACOLOGICAL RELEVANCE

Siparuna guianensis Aublet leaves, known as negramina, are used by indigenous and local communities in Brazil and other countries in the Americas to treat pain and inflammatory diseases.

AIM OF THE STUDY

To characterize the chemical constituents and to evaluate the antioxidant, anti-inflammatory, antinociceptive and locomotor activities of the dichloromethane fraction (DF) of S. guianensis leaves. Also, an acute oral toxicity test was accomplished.

MATERIAL AND METHODS

The chemical characterization of DF was performed by ultra-high pressure liquid chromatography (UHPLC) analyses coupled with a high-resolution mass spectrometer. The antioxidant potential of DF was investigated using nitric oxide (NO) and hydroxyl radical (OH) scavenging test. The evaluation study of the anti-inflammatory activity was carried out in vitro by NO measurement in stimulated macrophages and, in vivo, by croton oil-induced ear edema, LPS-induced peritonitis, and zymosan-induced arthritis in mice. Different mechanisms of central and peripheral nociception were stimulated by acetic acid-induced writhing, formalin, and tail-flick tests. Besides that, the open field assay was performed.

RESULTS

UHPLC analyses of DF showed the presence of a mixture of glycosylated and methoxylated flavonoids. DF was able to scavenge NO and OH radicals in vitro and showed anti-inflammatory activity by inhibiting NO production in LPS-stimulated murine macrophages. Oral administration of DF considerably inhibited the ear edema after croton oil application and reduced the leukocyte infiltrated in LPS-induced peritonitis. In the inflammatory intra-articular zymosan-induced process, DF showed a significant reduction in the inflammatory area and of the cells in the synovial and connective tissues adjacent to the joint. Also, DF was able to reduce the intra-articular edema. In nociception models, the oral administration of DF considerably inhibited the acetic acid-induced writhings. The formalin test showed that DF attenuated the licking time in both phases, which suggested that DF reduce the nociception by central and peripheral mechanisms. In the tail-flick test, DF showed no activity. Besides that, DF did not affect the animal locomotion, and no acute toxicity was observed.

CONCLUSIONS

For the first time, the anti-inflammatory and antinociceptive activities of S. guianensis were reported, supporting its ethnopharmacological uses for some inflammatory diseases and painful conditions.

Anti-inflammatory and antinociceptive activities of a phenylpropanoid-enriched fraction of Duguetia furfuracea

A previous study reported the in vivo anti-inflammatory and antinociceptive activities of essential oil of the underground stem bark of Duguetia furfuracea, termed EODf. This study aimed to obtain a phenylpropanoid-enriched fraction from the D. furfuracea (EFDf) essential oil and to investigate its anti-inflammatory and antinociceptive effects. The chemical composition of the EFDf was determined by gas chromatography-mass spectrometry (GC-MS). The in vivo anti-inflammatory activity was evaluated with a lipopolysaccharide (LPS)-induced paw oedema model. The effects of the EFDf on the polymorphonuclear leukocyte recruitment and the inducible nitric oxide synthase (iNOS) expression were evaluated in mice footpads. Moreover, the in vivo antinociceptive effect was assayed using the formalin test and the LPS-induced thermal hyperalgesia model. In the EFDf, 8 major compounds were identified, with α-asarone (36.4%) and 2,4,5-trimethoxystyrene (27.8%) the main constituents. A higher concentration of phenylpropanoid derivatives was found in the EFDf, 64.2% compared to the EODf (38%). The oral (p.o.) treatment with the EFDf at a dose of 3 mg/kg significantly attenuated the paw oedema, polymorphonuclear leukocyte migration, iNOS expression, and tumour necrosis factor alpha (TNF-α) production. The EFDf (10 and 30 mg/kg) also inhibited both phases of the formalin test and caused a significant increase in the reaction time in the LPS-induced thermal hyperalgesia model. Finally, EFDf-treated animals did not show any alteration of motor coordination. The results suggest that the enrichment of 2,4,5-trimethoxystyrene and α-asarone enhances the anti-inflammatory activity of the EFDf compared to the EODf. In contrast, the antinociception promoted by the EFDf was similar to the EODf and was mediated via activation of adenosinergic and opioidergic receptors.

Synthesis and evaluation of pharmacological activities of some 3-O-benzyl-4-C-(hydroxymethyl)-1,2-O-isopropylidene-α-D-ribofuranose derivatives as potential anti-inflammatory agents and analgesics

Background and purpose:

α-D-ribofuranose analogues are reported to have multifarious biological properties such as analgesic, anti-inflammatory, and antiviral activities. The present study aims to synthesize some α-D- ribofuranose derivatives and investigate their biological properties.

Experimental approach:

Four derivatives (2a, 2b, 3, and 4) were synthesized from the starting material 3-O- benzyl-4-C-(hydroxymethyl)-1,2-O-isopropylidene-α-D-ribofuranose via subsequent benzylation, tosylation, and acetylation reactions in good yields. The compounds were confirmed by spectroscopic methods such as Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (¹HNMR), and then evaluated for various pharmacological activities using standard in vitro and in vivo procedures.

Findings / Results:

Compound 2a (50 mg/kg) exhibited both central and peripheral analgesic activity in the tail immersion test (2.52 ± 0.14 min tail flicking reaction time after 30 min from administration, P < 0.001) and the acetic acid-induced writhing test (65.33 ± 2.06% reduction in abdominal writhing, P < 0.001) respectively. In the anti-inflammatory assay, percent paw edema inhibition of carrageenan-induced rats for compounds 2a and 4 (100 mg/kg) after 4 h of administration were 82.6% (P < 0.001) and 87.6% (P < 0.001), respectively. The compounds were also tested for antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, antimicrobial property in disk diffusion assay, and cytotoxicity in HeLa cell line; however, no significant results were observed in any of those tests.

Conclusion and Implications:

Our study indicated that some of the synthesized compounds exhibited promising analgesic and anti-inflammatory effects and may serve as potential lead compounds.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Anti-inflammatory and central and peripheral anti-nociceptive activities of α-asarone through the inhibition of TNF-α production, leukocyte recruitment and iNOS expression, and participation of the adenosinergic and opioidergic systems

Alpha-asarone has been found to possess many pharmacological activities, which can improve cognitive function and exert anti-oxidant, anxiolytic, anti-epileptic and protective effects against endothelial cell injury. The anti-inflammatory activity of α-asarone was evaluated using lipopolysaccharide (LPS)-induced paw oedema. Moreover, leukocyte migration, inducible nitric oxide synthase (iNOS) expression and tumour necrosis factor-alpha (TNF-α) levels were quantified in footpads. Formalin and LPS-induced thermal hyperalgesia models were generated using adenosinergic, opioidergic, serotonergic and muscarinic receptor antagonists. The effects on motor coordination were evaluated by means of the rota-rod test. Oral treatment (p.o.) with α-asarone (3 mg/kg) significantly inhibited paw oedema by 62.12 and 72.22%, 2 and 4 h post LPS injection, respectively. Alpha-asarone (3 mg/kg, p.o.) attenuated the inflammatory infiltrate 1, 3 and 6 h after LPS injection. Furthermore, α-asarone (3 mg/kg, p.o.) suppressed iNOS expression and TNF-α production, 6 and 1 h after inflammatory stimulus, respectively. Alpha-asarone (3, 10 and 30 mg/kg, p.o.) inhibited both phases of formalin-induced licking. In the hot-plate test, α-asarone (10 and 30 mg/kg, p.o.) increased the latency to response 3 and 5 h post LPS stimulus. Caffeine and naloxone abolished the central anti-nociceptive effect of α-asarone (neurogenic phase of formalin and hot plate tests), suggesting the participation of the adenosinergic and opioidergic systems. Furthermore, naloxone reversed the peripheral activity of α-asarone (inflammatory phase of formalin test), indicating the possible involvement of the opioidergic pathway. In the rota-rod test, α-asarone did not change motor coordination. These findings suggest that α-asarone has anti-inflammatory, peripheral and central anti-nociceptive effects and could represent a promising agent for future research.

Chemical composition and evaluation of the anti-inflammatory and antinociceptive activities of Duguetia furfuracea essential oil: Effect on edema, leukocyte recruitment, tumor necrosis factor alpha production, iNOS expression, and adenosinergic and opioidergic systems

ETHNOPHARMACOLOGICAL RELEVANCE

Duguetia furfuracea (A. St. -Hil.) Saff. (Annonaceae) is commonly known in Brazil as "araticum-seco," and its root is used in folk medicine to treat inflammatory and painful disorders. However, no studies have been performed to evaluate these therapeutic activities.

AIM OF THE STUDY

Investigate the chemical composition, anti-inflammatory and antinociceptive effects, and elucidate the possible antinociceptive mechanisms of action from the essential oil of D. furfuracea (EODf) underground stem bark.

MATERIALS AND METHODS

Chemical composition was determined by gas chromatography and mass spectrometry (GC/MS). The paw edema induced by LPS, formalin-induced nociception, LPS-induced thermal hyperalgesia and rota-rod tests in vivo were used to evaluate the anti-inflammatory and antinociceptive effects in addition to the alteration on motor coordination. Histological analyses and an immunohistochemistry assay for iNOS were performed on mouse footpads of naive, control, 10 mg/kg EODf, and 10 mg/kg indomethacin (Ind) groups. The samples were removed at 1, 3, and 6 h after subplantar injection of LPS. In addition, the involvement of the adenosinergic, opioidergic, serotonergic, and cholinergic systems were investigated, in order to elucidate possible antinociceptive mechanisms.

RESULTS

Twenty-four volatile constituents were detected and identified. (E)-asarone (21.9%), bicyclogermacrene (16.7%), 2,4,5-trimethoxystyrene (16.1%), α-gurjunene (15%), cyperene (7.8%), and (E)-caryophyllene (4.6%) were major compounds found in EODf. Oral treatment (p.o.) with EODf (1, 3, and 10 mg/kg) significantly inhibited the paw edema induced by LPS. At 10 mg/kg EODf promoted inhibition of tumor necrosis factor alpha (TNF-α) production, recruitment of polymorphonuclear (PMN) leukocytes and inducible nitric oxide synthase (iNOS) expression in paw tissue. EODf (10 and 30 mg/kg, p.o.) also reduced licking time in both phases of the formalin test and it had a significant effect on the LPS-induced thermal hyperalgesia model. The administration of caffeine (Caf) and naloxone (Nal) reversed the antinociceptive activity of EODf, in the first phase of the formalin test and in the LPS-induced thermal hyperalgesia model. Moreover, Nal was also able to abolish the antinociception caused by EODf, in the second phase of formalin test. In the rota-rod test, EODf-treated animals did not show any alteration of motor coordination.

CONCLUSIONS

Our findings indicate that EODf underground stem bark produces anti-inflammatory and both central and peripheral antinociceptive effects. Furthermore, the antinociceptive activity of EODf underground stem bark is possibly mediated by adenosinergic and opioidergic pathways, and its properties do not induce effects on motor coordination. These results support the use of the folk medicine, D. furfuracea root, to treat inflammation and painful conditions.