Antinociceptive effect of ethanol extract of leaves of Lannea coromandelica

Involvement of GABAergic and Serotonergic Systems in the Antinociceptive Effect of Jegosaponin A Isolated from Styrax japonicus

The antinociceptive activity of the flower extracts of Styrax japonicus was confirmed in our previous study. However, the key compound for analgesia has not been distinguished, and the corresponding mechanism is obscure. In this study, the active compound was isolated from the flower by multiple chromatographic techniques and structurally illustrated using spectroscopic methods and referring to the related literature. The antinociceptive activity of the compound and the underlying mechanisms were investigated using animal tests. The active compound was determined to be jegosaponin A (JA), which showed significant antinociceptive responses. JA was also shown to possess sedative and anxiolytic activities but no anti-inflammatory effect, implying the association of the antinociceptive effects with the sedative and anxiolytic activities. Further antagonists and calcium ionophore tests showed that the antinociceptive effect of JA was blocked by flumazenil (FM, antagonist for GABA-A receptor) and reversed by WAY100635 (WAY, antagonist for 5-HT_1A receptor). Contents of 5-HT and its metabolite (5-HIAA) increased significantly in the hippocampus and striatum tissues after JA administration. The results indicated that the antinociceptive effect of JA was regulated by the neurotransmitter system, especially GABAergic and serotonergic systems.

In Vivo Bioactivities of Hoya parasitica (Wall.) and In Silico Study against Cyclooxygenase Enzymes

Hoya parasitica (Wall.) is extensively used in traditional medicine for the treatment of various diseases including rheumatism, kidney problems, jaundice, urinary tract disorders, fever, and pain. The present study was designed to explore new lead compound(s) to alleviate pain, pyresis, and diarrhea from methanol, ethyl acetate, and n-hexane extracts of H. parasitica (Wall.) leaves (MHP, EAHP, and NHP, respectively). Analgesic activity of the extracts was assessed through acetic acid induced writhing, tail immersion, and hot plate tests while brewer's yeast-induced pyrexia test was employed for the assessment of antipyretic activity. Besides, castor oil and magnesium sulfate induced diarrheal tests were utilized for the evaluation of antidiarrheal properties. Moreover, in silico study of the isolated compounds was undertaken to seek out best-fit phytoconstituent(s) against cyclooxygenase enzymes. MHP revealed substantial antioxidant activities in different in vitro assays compared to EAHP and NHP. In the acetic acid-induced writhing test, among the extracts, MHP (400 mg/kg) revealed maximum 74.15 ± 1% inhibition of writhing comparable to that of standard (85.77 ± 1.39%). Again, in tail immersion and hot plate tests, higher doses of all the test samples exhibited a significant increase of latent period in a time-dependent manner. In brewer yeast-induced pyrexia test, at 3rd and 4th hour of treatment, significant (P < 0.05) antipyretic action was found in the test samples. In both castor oil and magnesium induced diarrheal tests, MHP at 400 mg/kg showed the highest percent inhibition of diarrhea (68.62 ± 4.74 and 64.99 ± 2.90, respectively). Moreover, molecular docking analysis corroborated the results of the present study. The findings of the present study supported the traditional uses of this plant for the alleviation of pain and fever. Furthermore, hoyasterone was found to be the most effective lead compound as cyclooxygenase enzyme inhibitor.

Central and peripheral pain intervention by Ophiorrhizarugosa leaves: Potential underlying mechanisms and insight into the role of pain modulators

ETHNOPHARMACOLOGICAL RELEVANCE

Ophiorrhiza rugosa var. prostrata is a traditional medicinal plant used by the indigenous and local tribes (Chakma, Marma and Tanchangya) of Bangladesh for the management of chest pain, body ache, and earache. However, the knowledge of anti-nociceptive and anti-inflammatory potentials of this plant is scarce.

AIM OF THE STUDY

Therefore, we scrutinized the anti-nociceptive and anti-inflammatory properties of O. rugosa leaves along with its possible mechanism(s) of action using chemical and heat-induced pain models.

METHODS AND MATERIALS

O. rugosa was extracted using 100% ethanol (EEOR) followed by exploring phytochemicals and assessing acute toxicity. To determine anti-nociceptive potentials, chemical-induced (acetic acid and formalin) and heat-induced (hot plate and tail immersion) nociceptive models were followed. To investigate the possible involvement of opioid receptors during formalin, hot plate, and tail immersion tests, naltrexone was administered whereas methylene blue and glibenclamide were used to explore cGMP involvement and ATP-sensitive K⁺ channel pathways, respectively. Moreover, the anti-inflammatory potential was assessed using the carrageenan-induced paw edema test model. Motor behaviours of EEOR were assessed by the open-field test. Finally, bioactive constituents (identified by GC-MS) from O. rugosa were subjected to molecular docking and ADME/t analysis to evaluate its potency and safety.

RESULTS

During chemical-induced and heat-induced pain models, EEOR exhibited significant and effective nociception suppression at all experimental doses (200 and 400 mg/kg). Also, the administration of naltrexone corroborated the association of opioid receptors with the anti-nociceptive activity by EEOR. Similarly, cGMP and ATP-sensitive K⁺ channel pathways were also found to be involved in the anti-nociceptive mechanism. Furthermore, significant and dose-dependent inhibition of inflammation induced by carrageenan was recorded for EEOR. Both doses of EEOR did not affect the animal's locomotor capacity in the open-field test. Besides, in silico test identified the key compounds (loliolide, harman, squalene, vitamin E, and gamma-sitosterol) that inhibited some particular receptors regarding pain and inflammation.

CONCLUSION

This research exposes central and peripheral pain intervention as well as anti-inflammatory activity of O. rugosa. Also, the identified compounds from this plant support its activities by effectively inhibiting anti-nociceptive and anti-inflammatory receptors. Overall, these outcomes valorize the ethnomedicinal efficacy of O. rugosa in managing various painful conditions.

A Systematic Review of Traditionally Used Herbs and Animal-Derived Products as Potential Analgesics

Pain is a distressing but fundamental manifestation that prepares the body for potentially detrimental stimuli while ensuring its protection. Plant and animal products have traditionally been used to relieve pain for centuries. However, no attempt has been made to compile a single report of plant and animal products possessing analgesic properties. This review enadeavours to recover data from published articles to establish a collective literature review on folk remedies from plant and animal sources used as analgesics and in the treatment of pain-related conditions, identifying gaps in existing knowledge and future works. Relevant information was systematically retrieved using the PRISMA method. In this review, in total, 209 plants were found to be either used raw or prepared by decoctions or maceration. Administration was either oral or topical, and they were predominantly used in Asian countries. In vivo studies of plants with analgesic properties, which were tested using different methods including acetic-induced writhing test, hotplate test, tail-flick test, and formalin-induced pain test, were compiled. Animal products with analgesic properties were obtained mainly from compounds present in venom; their bioactive compounds were also identified. In the literature search, certain gaps were noted, which could be reviewed in future studies. For instance, there was a disparity of information regarding the traditional uses of medicinal plants. In this review, an attempt was made to critically assess and describe the pharmacological properties and bioactive composition of indigenous plants, some animal species, and animal venom by scrutinizing databases and looking for published articles. Therefore, it can be concluded that the compounds obtained from these sources can serve as important ingredients in therapeutic agents to alleviate pain once their limitations are assessed and improved upon. In the literature search, certain gaps were noted, which could be reviewed in future studies.

Tannin-rich extracts from Lannea stuhlmannii and Lannea humilis (Anacardiaceae) exhibit hepatoprotective activities in vivo via enhancement of the anti-apoptotic protein Bcl-2

The potential hepatoprotective activities of two Lannea species were explored in vivo. Furthermore, the binding activities of their main polyphenols to the antiapoptotic protein Bcl-2 were investigated. Based on HPLC-MS/MS results, 22 secondary metabolites were characterized in L. stuhlmannii (mainly tannins), while 20 secondary metabolites (mainly sulphated tannins) were identified in L. humilis. Both extracts exhibited substantial antioxidant activities in vitro and counteracted D-galactosamine induced intoxication in rats in vivo and increased the total antioxidant capacity (TAC) of liver tissues. In addition to reducing the elevated levels of AST and total bilirubin, both extracts significantly attenuated the deleterious histopathologic changes in liver after D-galactosamine-intoxication. Also, both extracts protected hepatocytes from apoptotic cell death and increased the expression of the anti-apoptotic protein Bcl-2. The identified compounds from both extracts can bind to the Bcl-2: Bim (BH3) interface with an appreciable binding free energy. Hydrogen and ionic bonds and hydrophobic interactions with amino acid residues in the hydrophobic face of Bim (BH3) domain were discovered. To sum up, L. humilis and L. stuhlmanni exhibited promising hepatoprotective activities in vivo against D-GalN-induced liver injury and their hepatoprotection is due to the antioxidant and anti-apoptotic effects of tannins and proanthocyanidins.

Chemical characterization and pharmacological assessment of polysaccharide free, standardized cashew gum extract (Anacardium occidentale L.)

ETHNOPHARMACOLOGICAL RELEVANCE

The cashew gum (Anacardium occidentale L.) is used in traditional Brazilian medicine in the treatment of inflammatory conditions, asthma, diabetes, and gastrointestinal disturbances.

AIM OF THE STUDY

In the present study, we aimed at forming a chemical characterization and investigation of the antinociceptive and anti-inflammatory activities of the aqueous extract of cashew gum without the presence of polysaccharides in its composition (CGE).

MATERIALS AND METHODS

The CGE was obtained after the precipitation and removal of polysaccharides through the use of acetone. After, the acetone was removed by rotaevaporation, and the concentrated extract was lyophilized. The chemical characterization of CGE was performed by liquid chromatography mass spectrometry (LC-MS) and tandem mass spectrometry (MS/MS) analyses. Mice were used for the evaluation of the antinociceptive and anti-inflammatory activities. CGE was analyzed via the Irwin test, acetic acid-induced writhing test, formalin-induced pain test, and carrageenan-induced paw edema test. The motor activity or probable sedation was verified through the chimney, open-field, and sodium pentobarbital-induced sleep tests. We investigated if the analgesic and anti-inflammatory effects of CGE depend of reduction in PGE₂ levels, were performed the carrageenan or PGE₂-induced hyperalgesia tests.

RESULTS

The chemical characterization of CGE showed the presence of anacardic acids as the predominant phytoconstituents. The treatment with CGE (75, 150, and 300mg/kg, p.o.) inhibited the number of writhing in a dose-dependent manner. With an intermediate dose, CGE did not cause motor impairment with the chimney test or alterations in either the open-field or sodium pentobarbital-induced sleep. In the formalin-induced pain test, CGE (150mg/kg, p.o.) produced an antinociceptive effect only in the first phase of the test, suggesting anti-inflammatory activity. With the same dosage, CGE also reduced the carrageenan-induced paw edema at all hours of the test, confirming its anti-inflammatory effect. Furthermore, CGE (150mg/kg, p.o.) presented an antihyperalgic effect at all hours of the carrageenan-induced hyperalgesia test. However, this dose of CGE was not able to reduce the hyperalgesia induced by PGE₂, suggesting that the anti-inflammatory effect of this extract depends on the reduction in the PGE₂ levels.

CONCLUSION

The anacardic acids are the predominant phytoconstituents identified in the CGE. The action mechanisms of CGE suggest the reduction in the PGE₂ levels. These findings support the use of cashew gum in popular medicine and demonstrate that part of its antinociceptive and anti-inflammatory effects should also be attributed to the presence of anacardic acids in its composition, independent of the presence of polysaccharides.

Antinociceptive Activity of Macaranga denticulata Muell. Arg. (Family: Euphorbiaceae): In Vivo and In Silico Studies

Background: The present study was conducted to investigate the antinociceptive activity of methanol extract of Macaranga denticulata (Met.MD) in an animal model, followed by molecular docking analysis. Methods: Antinociceptive activity was determined by acetic acid-induced writhing and formalin-induced licking test in mice. Then, molecular docking study was performed to identify compounds having maximum activity against the COX-1 enzyme using Schrödinger Maestro (version 10.1) to determine docking fitness. Results: A preliminary phytochemical analysis of Met.MD revealed that it contained alkaloids, carbohydrates, phenols, flavonoids, tannins, and terpenoids. Met.MD exhibited a dose-dependent and statistically significant antinociceptive activity in the acetic acid and formalin test at the doses of 200 and 400 mg/kg. In addition, our docking study showed that macarangin had the best fitness score of −5.81 with COX-1 enzyme among six major compounds of M. denticulata. Conclusions: Results of the present study confirmed the potential antinociceptive activity of M. denticulata leaf extract in both in vivo and in silico models.

Lannea coromandelica (Houtt.) Merr. Induces Heme Oxygenase 1 (HO-1) Expression and Reduces Oxidative Stress via the p38/c-Jun N-Terminal Kinase-Nuclear Factor Erythroid 2-Related Factor 2 (p38/JNK-NRF2)-Mediated Antioxidant Pathway

The leaves of Lannea coromandelica (Houtt.) Merr. are used in the Garo, Pahan, and Teli tribal communities of Bangladesh as a traditional medicinal plant to treat hepatitis, diabetes, ulcers, heart disease, and dysentery. However, there have been limited phytochemical and biological studies on the bark of L. coromandelica. This study aimed to investigate the antioxidant activities of L. coromandelica bark extract (LCBE) and the underlying mechanism using RAW 264.7 cells. The LCBE was analysed by high-pressure liquid chromatography (HPLC) to detect its key polyphenolic compounds. Various in vitro antioxidant assays were performed using RAW 264.7 cells to assess the antioxidant effects of the LCBE and to understand the underlying molecular mechanism. HPLC revealed the presence of gallic acid, (−)-epigallocatechin-3-gallate, catechin, chlorogenic acid, and caffeic acid in the LCBE. The extract showed a very potent capacity to scavenge numerous free radicals through hydrogen atom transfer and/or electron donation and also quenched cellular reactive oxygen species (ROS) generation without showing any toxicity. The LCBE was found to combat the oxidative stress by enhancing the expression, at both transcriptional and translational levels, of primary antioxidant enzymes as well as phase II detoxifying enzymes, especially heme oxygenase 1, through the upregulation of the nuclear factor erythroid 2-related factor 2 (NRF2)-mediated pathway in RAW 264.7 cells via the phosphorylation of p38 kinase and c-Jun N-terminal kinase (JNK). The LCBE exhibited strong antioxidant activities and mitigated the cellular ROS production. These results provide scientific evidence of its potential as an ideal applicant for a cost-effective, readily available, and natural phytochemical, as well as a strategy for preventing diseases associated with oxidative stress and attenuating disease progress.

The ethyl acetate fraction from Physalis alkekengi inhibits LPS-induced pro-inflammatory mediators in BV2 cells and inflammatory pain in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Physalis alkekengi is an edible herb whose fruit and calyx are traditionally used to treat a wide range of diseases including inflammation, toothache, and rheumatism. However, the effects of Physalis alkekengi fruit along with its calyx (PAF) on neuroinflammation and inflammatory pain behavior have not been reported yet.

AIM OF THE STUDY

This study evaluated the anti-inflammatory effect of PAF on lipopolysaccharide (LPS)-induced neuroinflammation and several in vivo model of inflammatory pain in mice.

MATERIALS AND METHODS

Here, first we studied the effects of PAF fractions on the production of pro-inflammatory mediators in LPS-treated BV2 microglial cells using enzyme-linked immunosorbent assay. The translocation of nuclear factor-kappa B (NF-κB) and the involvements of Akt and mitogen-activated protein (MAP) kinases in ethyl acetate fraction of PAF (PAF-EA)-mediated anti-inflammatory effect were measured using Western blotting. In in vivo experiments, the efficacy of PAF-EA was evaluated at the doses of 100 and 200mg/kg using several chemical-induced models of inflammatory pain such as acetic acid-induced writhing, formalin-induced paw licking and edema.

RESULTS

We found that compared to other fractions, the PAF-EA more potently inhibited the LPS-induced generation of nitric oxide, tumor necrosis factor-α, interleukin-6 and reactive oxygen species. It also inhibited LPS-induced nuclear translocation of NF-κB. These actions of EA fraction were found to be associated with a disruption of Akt and MAP kinases signaling pathways. The EA fraction also significantly inhibited acetic acid-induced writhing, formalin-induced licking time and edema in mice.

CONCLUSIONS

Our findings support the ethnopharmacological use of P. alkekengi fruit along with its calyx as an anti-inflammatory agent and suggest that the EA fraction of PAF may serve as a potential candidate to treat different neurological disorders and pain associated with inflammation.

Endogenous opiates and behavior: 2014

This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).

Evaluation of Antinociceptive Activity of Ethanol Extract of Leaves of Adenanthera pavonina

Adenanthera pavonina is a deciduous tree commonly used in the traditional medicine to treat inflammation and rheumatism. The aim of this study was to evaluate the antinociceptive activity of ethanol extract of leaves of A. pavonina (EEAP). EEAP was investigated using various nociceptive models induced thermally or chemically in mice including hot plate and tail immersion test, acetic acid-induced writhing, and glutamate- and formalin-induced licking tests at the doses of 50, 100, and 200 mg/kg body weight (p.o.). In addition, to assess the possible mechanisms, involvement of opioid system was verified using naloxone (2 mg/kg) and cyclic guanosine monophosphate (cGMP) signaling pathway by methylene blue (MB; 20 mg/kg). The results have demonstrated that EEAP produced a significant and dose-dependent increment in the hot plate latency and tail withdrawal time. It also reduced the number of abdominal constrictions and paw lickings induced by acetic acid and glutamate respectively. EEAP inhibited the nociceptive responses in both phases of formalin test. Besides, the reversal effects of naloxone indicated the association of opioid receptors on the exertion of EEAP action centrally. Moreover, the enhancement of writhing inhibitory activity by MB suggests the possible involvement of cGMP pathway in EEAP-mediated antinociception. These results prove the antinociceptive activity of the leaves of A. pavonina and support the traditional use of this plant.

Evaluation of antinociceptive activity of ethanol extract of bark of Polyalthia longifolia

ETHNOPHARMACOLOGICAL RELEVANCE

Polyalthia longifolia var. pendula is a very popular herb in Bangladesh due to its traditional uses in treatment of rheumatism, bone fracture and gastric ulcer. The present study was conducted to investigate the antinociceptive activity of ethanol extract of P. longifolia (EEPL) bark.

MATERIALS AND METHODS

Hot plate and tail immersion tests, acetic acid-induced writhing test, glutamate and formalin-induced paw licking tests in mice were employed in this study. In all the experiments EEPL was administered orally at the doses of 50, 100 and 200mg/kg body weight. To investigate the possible participation of opioid system in EEPL-mediated effects, naloxone was used to antagonize the action.

RESULTS

EEPL showed a significant antinociceptive activity against both heat and chemical-induced nociception. The effects were dose-dependent and significant at the doses of 100 and 200mg/kg of EEPL. Besides, pretreatment with naloxone caused significant inhibition of the antinociceptive activity induced by EEPL, revealing the possible involvement of the opioid receptors.

CONCLUSION

These results indicate the antinociceptive activity of the bark of P. longifolia and support the ethnomedical use of this plant in treatment of different painful conditions.