Synergistic antidepressant-like effect of xylopic acid co-administered with selected antidepressants

Background

Xylopic acid (XA), a kaurene diterpene from the dried fruits of Xylopia aethiopica, has anxiolytic- and antidepressant-like activity in mice and zebrafish. We aimed to assess the potential synergistic antidepressant-like effects of XA when combined with selected antidepressants in the mouse forced-swim test.

Materials and methods

The antidepressant-like effect of xylopic acid (XA) (10, 30, 100 mgkg-1), fluoxetine (Flx) (3, 10, 30 mgkg-1), sertraline (Sert) (3, 10, 30 mgkg-1), imipramine (Imi) (10, 30, 100 mgkg-1) and ketamine (Ket) (0.1, 0.3, 1.0 mgkg-1), was evaluated in forced swim test. The dose (ED50) that achieved a 50% reduction in immobility time was determined from the respective log-dose response curves. XA and the selected antidepressants were co-administered in fixed-dose ratio combinations (1/2:1/2, 1/4:1/4, 1/8:1/8) of the ED50 to identify the experimental ED50 (ED50mix). The theoretical ED50(ED50add), of all combinations was determined using isobolograms and compared with the ED50mix to identify the nature of the interaction. The effect of dose combinations on general locomotor activity was assessed in the open-field test.

Results

The interaction index (γ) for the following XA combinations, XA/Flx, XA/Sert, XA/Imi and XA/Ket were 0.42, 0.41, 0.31 and 0.34. An independent sample t-test revealed that the experimental ED50 (ED50mix) was significantly lower than the theoretical ED50 (ED50add) in all combinations of XA, indicative of a synergistic antidepressant-like effect. However, combinations of XA with ketamine significantly reduced general locomotor activity at all dose combinations.

Conclusion

The co-administration of xylopic acid and fluoxetine, imipramine, sertraline and ketamine produces a synergistic antidepressant-like effect in mice.

Anxiolytic-like effects of Pseudospondias microcarpa hydroethanolic leaf extract in zebrafish: Possible involvement of GABAergic and serotonergic pathways

Pseudospondias microcarpa is used in ethnomedicine to manage central nervous system diseases. The hydroethanolic extract (PME) from the leaves of the plant has shown anxiolytic-like properties in mice anxiety models. However, its effects in chronic anxiety models and possible mechanism(s) of action were not studied. Therefore, the current study evaluated the anxiolytic-like mechanisms of PME in zebrafish models of anxiety. The zebrafish light dark test (LDT) and novel tank test (NTT) were employed to assess the anxiolytic-like effects of PME (0.1, 0.3, 1.0 mg mL-1), fluoxetine (3 × 10-5 mg mL-1) and diazepam (1.5 × 10-7 mg mL-1). The chronic unpredictable stress (CUS) test was used to further evaluate the extract's anxiolytic-like properties. The potential mechanisms of anxiolytic action of the extract was evaluated after pre-treated with flumazenil, granisetron, methysergide, or pizotifen, all at 1 × 10-3 mg mL-1. The extract significantly decreased anxiety behaviours in the NT and LD tests. These observed effects of the extract were however counteracted by flumazenil, granisetron, methysergide and pizotifen pre-treatment. In addition, PME treatment significantly reversed CUS-induced anxiety behaviours in zebrafish. Results show that PME possesses anxiolytic-like effects possibly through interaction with serotonergic and gamma-aminobutyric acid mediated pathways.

Fast-onset effects of Pseudospondias microcarpa (A. Rich) Engl. (Anacardiaceae) hydroethanolic leaf extract on behavioral alterations induced by chronic mild stress in mice

INTRODUCTION

Pseudospondias microcarpa (Anacardiaceae) is a plant widely used traditionally for treating various central nervous system disorders. A previous study in our laboratory confirmed that the hydroethanolic leaf extract (PME) of the plant produces an antidepressant-like effect in rodent models of behavioral despair. However, its effect on depressive-like behavior induced by chronic mild stress (CMS) and its time course of action are still unknown. In this context, the long-term effects of PME on cognitive function and depressive- and anxiety-like behavior caused by CMS were assessed.

METHODS

Male ICR mice were exposed to CMS for nine weeks and anhedonia was evaluated by monitoring sucrose intake (SIT) weekly. PME (30, 100, or 300 mg kg-1) or fluoxetine (FLX) (3, 10, or 30 mg kg-1) was administered to the mice during the last six weeks of CMS. Behavioral tests-coat state, splash test, forced swimming test (FST), tail suspension test (TST), elevated plus maze (EPM), open field test (OFT), novelty suppressed feeding (NSF), EPM transfer latency, and Morris water maze (MWM)-were performed after the nine-week CMS period.

RESULTS

When the mice were exposed to CMS, their SIT and grooming behavior reduced (splash test), their coat status was poor, they became more immobile (FST and TST), more anxious (OFT, EPM, and NSF), and their cognitive function was compromised (EPM transfer latency and MWM tests). Chronic PME treatment, however, was able to counteract these effects. Additionally, following two (2) weeks of treatment, PME significantly boosted SIT in stressed mice (30 mg kg-1, P<0.05; 100 mg kg-1, P<0.05; and 300 mg kg-1, P<0.001), as compared to four (4) weeks of treatment with FLX.

CONCLUSION

The present findings demonstrate that PME produces a rapid and sustained antidepressant-like action and reverses behavioral changes induced by chronic exposure to mild stressors.

Effect of Diclofenac and Andrographolide Combination on Carrageenan-Induced Paw Edema and Hyperalgesia in Rats

Studies into drug combination at low doses are a promising approach to the management of pain and inflammation. The aim of this study was to evaluate the anti-edema and anti-hyperalgesic effects of a combination of diclofenac and andrographolide. Male Sprague-Dawley rats were first treated with diclofenac or andrographolide alone (3–100 mg/kg), as well as a combination of the 2 drugs. Carrageenan was then injected into the right hind paw of rats, and changes in paw volume and sensitivity to mechanical (von Frey) and thermal (Hargreaves test) stimuli measured. Results showed drug combination produced synergistic effects at reducing paw edema especially at lower doses, with a Loewe synergy score of 13.02 ± 8.75 in SynergyFinder and a combination index of .41 ± .18 after isobolographic analysis. Again synergy scores for decreasing response to 1.0 and 3.6 g force application of von Frey filaments after drug combination were 10.127 ± 5.68 and 8.554 ± 6.53, respectively, in SynergyFinder. Synergistic effects were also seen after drug combination in the Hargreaves test with a synergy score of 5.136 ± 16.38. In conclusion, combination of diclofenac with andrographolide showed better pharmacologic effects after carrageenan injection and was more synergistic at low-dose combinations.

Predictors of medication nonadherence among hypertensive clients in a Ghanaian population: Application of the Hill‐Bone and Perceived Barriers to Treatment Compliance Scale

Background and Aim

Nonadherence to antihypertensive medication impairs optimal blood pressure and is influenced by multiple interrelating factors. Knowing the complexity of medication nonadherence and its associated factors is essential for intervention strategies. This study evaluated the predictors of medication nonadherence among hypertensive clients in a Ghanaian population.

Methods

This was a hospital‐based cross‐sectional study conducted at the Hypertensive Clinic of the Kwame Nkrumah University of Science and Technology (KNUST) Hospital, Kumasi, Ghana. A self‐designed questionnaire, the Hill‐Bone Compliance to High Blood Pressure Therapy and Perceived Barriers to Treatment Compliance Scales, were used for data collection from 246 hypertensives. Data were analyzed using Statistical Package for Social Sciences, version 25.

Results

Medication nonadherence was observed among 8.5% of the study participants. In a multivariate regression model perceived noneffectiveness of medication (odds ratio [OR] = 1.76, 95% confidence interval [CI]: 1.34–2.31, p < 0.001) and barriers to alcohol and smoking cessation (OR = 2.83, 95% CI: 1.31–6.13, p = 0.008) were associated increased odds of antihypertensive medication nonadherence. Also, patients who do not know their total prescription (OR = 8.81, 95% CI: 2.28–34.0, p = 0.002) were more likely to be nonadherent to their antihypertensive medications. Moreover, clients who associate signs/symptoms of palpitations (OR = 5.82, 95% CI: 1.31–25.80, p = 0.021), poor sleep (OR = 3.92, 95% CI: 1.09–14.12, p = 0.036) and decreased sexual drive (OR = 4.74, 95% CI: 0.96–23.28, p = 0.055), were more likely to be nonadherent to antihypertensive medication.

Conclusion

In conclusion, we observed a lower nonadherence rate among hypertensive clients in a Ghanaian population with correlates being medication‐related factors. Most importantly, perceived noneffectiveness of medication, barriers to smoking and alcohol cessation, palpitations, poor sleep, and decreased sexual drive significantly predicted lower adherence and could serve as indicators for high risk of nonadherence to antihypertensive medications.

Antinociceptive effects of a hydroethanolic stem bark extract of Burkea africana

Introduction

Pain is a major symptom of many clinical disorders and its relief has long been a concern for individuals across the globe. There is therefore an unmet need to search for new efficacious agents for the effective management of pain. The stem bark of the savanna tree Burkea africana (Hook) (Family: Leguminosae) is used in the Ghanaian traditional medicine for the treatment and management of various pain-related diseases.

Method

An acute oral toxicity study in mice was conducted by administering BAE (50–5000 mg kg⁻¹p.o.). Antinociceptive effect of BAE (50–1000 mg kg⁻¹p.o.) was evaluated using the acetic acid-induced abdominal constriction, acidic saline-induced muscle pain and formalin-induced pain models. The antinociceptive mechanism of BAE was also assessed using the formalin-induced pain model.

Results

The LD₅₀ of BAE was thus estimated to be above 5000 mg kg⁻¹ since none of the animals died in the acute toxicity study. Pretreatment with BAE (50–1000 mg kg⁻¹p.o.) significantly reduced the number of writhes after acetic-acid administration compared to the vehicle treated group. BAE also produced a significant and dose-dependent reversal of mechanical hyperalgesia induced by the injection of the acidic saline. Administration of BAE was able to significantly suppress both phases of the formalin test. This effect of the extract was however reversed by pretreatment with naloxone and granisetron.

Conclusions

BAE exhibits antinociceptive effects in rodent pain models with a possible involvement of 5-HT₃ receptors and opioidergic pathways.

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Burkea africana stem bark extract.

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Acetic acid-induced abdominal constriction.

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Acidic saline-induced muscle pain.

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Formalin-induced pain.

Antinociceptive effect of the hydroethanolic leaf extract of Calotropis procera (Ait) R. Br. (Apocynaceae): Possible involvement of glutamatergic, cytokines, opioidergic and adenosinergic pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Pain remains real and still a major problem in clinical medicine which requires new agents with improved efficacy for more therapeutic benefits. Plant sources can serve as a basis for the search for some novel drugs hence the analgesic effects of the hydroethanolic extract of Calotropis procera (CPE) which is widespread in Ghana and other tropical areas and used in folkloric medicine for painful and inflammatory conditions was evaluated.

MATERIALS AND METHODS

The analgesic properties of orally administered CPE at doses of 30, 100, and 300 mg/kg were evaluated in thermal (tail immersion), chemical (acetic acid-writhing, formalin-induced paw licking, glutamate-induced nociception) and mechanical (Randall-Selitto) tests for analgesia. The involvement of tumour necrosis factor-alpha (TNF-α), interleukin 1β (IL 1β), bradykinin, and prostaglandin E₂ (PGE₂) on the analgesic effects of CPE were also evaluated in hypernociception assays measuring mechanical pain thresholds.

RESULTS

The latency of tail withdrawal in the tail immersion test was significantly increased (p = 0.0001) while writhing induced by acetic acid was significantly reduced (p < 0.0001) on treatment with CPE (30-300 mg/kg). The extract also significantly inhibited both phase 1 and phase 2 nociceptive states induced by formalin comparable to morphine (p < 0.0001). Furthermore, the extract significantly attenuated hyper-nociception induced by TNF-α (p < 0.0001), interleukin 1β (p = 0.0102), bradykinin (p < 0.0001), and prostaglandin E₂ (p < 0.0001). Additionally, glutamate-induced paw licking was reduced significantly (p < 0.05). The antinociceptive effects exhibited by CPE (100 mg/kg) in the formalin test was reversed by systemic administration of naloxone (2 mg/kg) and theophylline (5 mg/kg) but not glibenclamide (8 mg/kg), granisetron (2 mg/kg), atropine (3 mg/kg), yohimbine (3 mg/kg, p.o.) nor nifedipine (10 mg/kg).

CONCLUSION

Overall, the hydroethanolic leaf extract of Calotropis procera possesses analgesic properties that is mediated possibly through the glutaminergic, opioidergic, and adenosinergic pathways.

Effectiveness of Highly Active Anti-retroviral Therapy (HAART) in the Adult Population in the Ashanti Region of Ghana

  AIDS is the late stage of infection with the Human Immunodeficiency Virus (HIV). Even though the Highly Active Antiretroviral Therapy (HAART) for the management of HIV/ AIDS has been in existence in Ghana since 2003, there is still limited data on their effectiveness. This study therefore sort to ascertain the effectiveness of HAART used at Anti-retroviral therapy (ART) Centres in the Ashanti region of Ghana by assessing its effects on immunological and haematological markers as well as some significant indicators such as body temperature and blood pressure changes. The study was a retrospective cross sectional study which reviewed medical record folders of 156 HIV infected patients who had attended the selected ART centres in the Ashanti region of Ghana between 2010 and 2014. About 49% of the study population had a significant rise in their CD4 counts after six months strict adherence to specific HAART regimen. HAART effectively reduced viral loads and increased CD4 counts in most of the patients whose medical record folders were reviewed. Socioeconomic factors, formal education and lack of health literacy had a significant effect on adherence to the HAART regimen, however; marital status of patients did not have any significant effect on adherence, CD4 counts and the haemoglobin concentration of patients. Based on results obtained from this study, HAART could be considered as effective in the adult population in the Ashanti region of Ghana provided there is a high level of adherence. Immunological and haematological markers for the assessment of effectiveness could also improve with high adherence recommended HAART regimen 

Evidence of an antidepressant-like effect of xylopic acid mediated by serotonergic mechanisms

BACKGROUND

Depression causes significant debilitating symptoms and economic burden. Current management is challenged by slow onset of action and modest efficacies of antidepressants; thus, the search for newer antidepressants remains relevant. We evaluated the antidepressant effects of a kaurene diterpene, xylopic acid (XA), in zebrafish and mouse models.

METHODS

The chronic unpredictable stress (CUS) protocol in zebrafish and the tail suspension test (TST), forced swim test (FST), lipopolysaccharide-induced depression-like behaviour test (LID) and repeated open space swimming test (OSST) in mice were used. We further examined the impact of depleting monoamines on XA's antidepressant effects. The contribution of glutamatergic and nitrergic pathways on the antidepressant effect of XA in mice and XA's effects on 5-HT receptors and monoamine oxidase (MAO) enzymes were also evaluated. Finally, XA's influence on neuroprotection was evaluated by measuring BDNF and oxidative stress enzymes in whole brain. XA doses (1-10 μM) in zebrafish and (10, 30, 100 mg kg-1) in mice exerted potent antidepressant-like potential in FST, TST, LID and showed fast-onset antidepressant-like property in the OSST.

RESULTS

The antidepressant-like properties in mice were reversed by blocking synthesis/release of serotonin but not noradrenaline using p-chlorophenylalanine and α-methyl-p-tyrosine, respectively. This antidepressant-like effect was potentiated by D-cycloserine and Nω-Nitro-L-arginine methyl ester (L-NAME) but not by D-serine and L-arginine. XA also evoked partial agonist-like effects on 5-hydroxytrptamine receptors on the rat fundus but it did not have MAO inhibition effect. It also increased BDNF, glutathione and antioxidant enzymes.

CONCLUSION

Therefore, xylopic acid possesses antidepressant-like effects largely mediated by serotonergic and neuroprotective mechanisms.

Synedrella nodiflora Extract Depresses Excitatory Synaptic Transmission and Chemically-Induced In Vitro Seizures in the Rat Hippocampus

Extracts of the tropical Cinderella plant Synedrella nodiflora are used traditionally to manage convulsive conditions in the West African sub-region. This study sought to determine the neuronal basis of the effectiveness of these plant extracts to suppress seizure activity. Using the hippocampal slice preparation from rats, the ability of the extract to depress excitatory synaptic transmission and in vitro seizure activity were investigated. Bath perfusion of the hydro-ethanolic extract of Synedrella nodiflora (SNE) caused a concentration-dependent depression of evoked field excitatory postsynaptic potentials (fEPSPs) recorded extracellularly in the CA1 region of the hippocampus with maximal depression of about 80% and an estimated IC₅₀ of 0.06 mg/ml. The SNE-induced fEPSP depression was accompanied by an increase in paired pulse facilitation. The fEPSP depression only recovered partially after 20 min washing out. The effect of SNE was not stimulus dependent as it was present even in the absence of synaptic stimulation. Furthermore, it did not show desensitization as repeat application after 10 min washout produced the same level of fEPSP depression as the first application. The SNE effect on fEPSPs was not via adenosine release as it was neither blocked nor reversed by 8-CPT, an adenosine A₁ receptor antagonist. In addition, SNE depressed in vitro seizures induced by zero Mg²⁺ and high K⁺ -containing artificial cerebrospinal fluid (aCSF) in a concentration-dependent manner. The results show that SNE depresses fEPSPs and spontaneous bursting activity in hippocampal neurons that may underlie its ability to abort convulsive activity in persons with epilepsy.

Neuropharmacological Assessment of the Hydroethanolic Leaf Extract of Calotropis procera (Ait). R. Br. (Apocynaceae) in Mice

BACKGROUND

Calotropis procera has been widely used traditionally for its analgesic and anti-inflammatory effects. It is also reportedly used in ethnomedicine for mental health disorders including epilepsy even in the absence of supporting scientific data. Thus, the potential of the plant to affect neurological functions was evaluated.

METHODS

Irwin's test was performed to determine the effect of the oral administration of the extract (30-3000 mg kg^-1) on gross behaviour and physiological function. The activity meter, rotarod, pentylenetetrazol- (PTZ-) induced convulsion, pentobarbitone-induced sleep test, and the tail immersion tests were used to evaluate the spontaneous activity, neuromuscular function, convulsive threshold, sedation, and analgesic effects of the Calotropis procera extract (30-1000 mg/kg), respectively, in mice.

RESULTS

Calotropis procera extract (CPE) exhibited significant (p < 0.0001) anticonvulsant and analgesic effects. There was a significant increase in withdrawal latency of the CPE-treated animals in the tail immersion test for analgesia (p < 0.0001), while latency and duration of PTZ-induced convulsions were positively modulated. Calotropis procera extract showed significant (p < 0.0001) central nervous system depressant effects in pentobarbitone-induced hypnosis at 100-1000 mg/kg and spontaneous activity test (30-1000 mg/kg). The extract also depicted impaired motor coordination at 100-1000 mg/kg dose levels. LD₅₀ was estimated to be above 1000 mg kg^-1.

CONCLUSIONS

Calotropis procera extract has significant central nervous system depressant and analgesic effects in mice.

A review of pharmacological effects of xylopic acid

Xylopic acid (15β-acetyloxy-kaur-16-en-19-oic acid) is a kaurene diterpene that can be obtained from various Xylopia spp. Xylopic acid has demonstrated several pharmacological activities in vitro and in vivo. The compound has shown promising effect as a potent analgesic, anti-inflammatory and anti-allergic agent. Xylopic acid is a CNS depressant and was able to ameliorate anxiety-like symptoms in mice in addition to its neuroprotective effects. Deleterious effects of xylopic acid on the reproductive system of mice have been well documented but extensive toxicity study detailing effect of the acid upon chronic exposure needs to be determined. Due to the heavy consumption of X. aethiopica fruits, it is recommended that the pharmacokinetics of xylopic acid be determined to ascertain the possible food-drug interaction that may occur when conventional drugs are taken together with foods containing xylopic acid.

Leaves and stems of Capparis erythrocarpos, more sustainable than roots, show antiarthritic effects

ETHNOPHARMACOLOGICAL RELEVANCE

Capparis erythrocarpos is a medicinal plant used widely in many parts of Africa for the management of pain and inflammatory conditions such as rheumatoid arthritis. Its wide range of use, popularity and high value, make C. erythrocarpos containing products a target for economically driven adulteration. This is made worse, by the use of roots, which are unsustainable plant parts. In addition, the mechanism of anti-inflammation is not clearly understood.

AIM OF THE STUDY

Therefore, this study comparatively evaluated the anti-arthritic and analgesic effects of the leaves, stems and roots of C. erythrocarpos, while elucidating the mechanism of anti-inflammation.

MATERIALS AND METHODS

Using the complete Freund's adjuvant arthritis model, the antiathritic effects were evaluated. The analgesic effects were determined by measuring responses to Von Frey filament number 9. Effects of C. erythrocarpos extracts on the levels of Interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNF-α) were determined using ELISA. Haematological and serum biochemical assays were also carried out.

RESULTS

The leaf, stem and root extracts significantly reduced paw volumes with ED₅₀ values (mg/kg) of 182.5, 181.5 and 36.4 respectively. The leaf extract at a dose of 100 mg/kg showed substantial analgesic activity with a decrease in the percentage response to Von Frey filament 9. However, there was no significant difference in activities of the leaf, stem and root extracts. Results from ELISA assays show that lower doses of the stem extracts reduce levels of IL-6. Lower doses of all extracts also reduce TNF-α levels. Haematological analysis showed extracts reversed elevated WBC and platelet levels. Toxicity evaluation with kidney and liver function tests indicated no significant differences between the treatment and control groups.

CONCLUSIONS

The leaves and stems, just as the roots, have antiarthritic and analgesic effects and can be used as more sustainable alternatives to the roots. This will support the continuous growth of the industry that has developed around C. erythrocarpos.

An isobolographic analysis of the anti-nociceptive effect of geraniin in combination with morphine or diclofenac

BACKGROUND

Geraniin, a dehydroellagitannin, is a major component of the aqueous extract of the aerial parts of Phyllanthus muellerianus (Kuntze) Exell. (Euphorbiaceae). Several Phyllanthus species are traditionally used for painful disorders. The anti-nociceptive effects of the aqueous extract of the aerial parts of P. muellerianus and of geraniin have been scientifically established. The aim of the paper is to determine whether a combination of geraniin and diclofenac or geraniin and morphine leads to better anti-nociceptive effects.

METHODS

The nature of the interactions of morphine and diclofenac with geraniin was evaluated by undertaking the isobolographic analysis. Mice were treated with geraniin (3-30 mg/kg), morphine (1-10 mg/kg), and diclofenac (10-100 mg/kg) to obtain the ED50 values of the agents in the formalin test. Dose-response curves were then obtained and analyzed after the co-administration of geraniin with morphine or diclofenac in fixed ratio (1:1) combinations based on specific fractions (1/2, 1/4, and 1/8) of their respective ED50 values for the formalin test.

RESULTS

Geraniin was less potent than morphine but more potent than diclofenac in the formalin-induced nociception. The isobolographic analysis of geraniin/morphine (G/M) and geraniin/diclofenac combinations (G/D) at different fractions revealed the potentiation of their anti-nociceptive effects. The degrees of potentiation, which were calculated as interaction indices, showed synergism for both combinations in both phase I (G/M: 0.040, G/D: 0.017) and phase II (G/M: 0.004, G/D: 0.002) of the formalin test.

CONCLUSIONS

The present study demonstrates synergism for the co-administration of geraniin with both morphine and diclofenac.

Albizia zygia root extract exhibits antipsychotic-like properties in murine models of schizophrenia

BACKGROUND

The root extract of Albizia zygia (DC.) J.F. Macbr. (Leguminosae) is used to manage mental disorders in African traditional medicine. However, its value, particularly, against negative and cognitive symptoms of schizophrenia have not been evaluated.

AIM

The aim of this study was to evaluate the antipsychotic properties of the hydroethanolic root extract of Albizia zygia (AZE) against positive, negative and cognitive symptoms of schizophrenia in animal models.

MATERIALS AND METHODS

The effects of AZE (30-300 mg kg^-1) were evaluated against apomorphine-induced cage climbing as well as ketamine -induced hyperlocomotion, -enhanced immobility, -impaired social interaction and novel object recognition. The propensity of AZE to induce catalepsy and to attenuate haloperidol-induced catalepsy were also investigated.

RESULTS

AZE 30-300 mg kg^-1 significantly reduced apomorphine-induced climbing behaviour as well as ketamine-induced hyperlocomotion, immobility and object recognition deficits (at least P < 0.05). Moreover, the extract showed no cataleptic effect but significantly inhibited haloperidol-induced catalepsy at a dose of 30 mg kg^-1 (P < 0.05).

CONCLUSION

The root extract of Albizia zygia exhibited an antipsychotic-like activity in mice with potential to alleviate positive, negative and cognitive symptoms of schizophrenia.

Anticonvulsant effect of the hydroethanolic leaf extract of Psydrax subcordata (DC.) Bridson in murine models

ETHNOPHARMACOLOGICAL RELEVANCE

Psydrax subcordata (DC.) Bridson is a tropical medicinal plant used traditionally for the management of epilepsy. However, there is little scientific evidence to support its use.

AIM OF STUDY

The current study investigated the anticonvulsant properties of the hydroethanolic leaf extract of Psydrax subcordata (PSE) in animal models.

MATERIALS AND METHODS

The anticonvulsant effects were evaluated in mouse models of acute seizures (pentylenetetrazole-, picrotoxin-, 4-aminopyridine-, strychnine- and maximal electroshock-induced seizure tests) and status epilepticus (Lithium/pilocarpine-induced SE). The role of GABAergic mechanisms in the actions of the extract was also examined by pre-treatment of animals with flumazenil in the pentylenetetrazole test.

RESULTS

The extract (30, 100 and 300mg/kg, p.o.) significantly delayed the onset and decreased the duration and frequency of pentylenetetrazole- and picrotoxin-convulsions. PSE also reduced the duration of tonic hind limb extensions in the maximal electroshock-induced seizure test. Furthermore, PSE pre-treatment significantly delayed the onset of seizures and improved survival in the 4-aminopyridine-induced seizure test. In the strychnine-induced seizure test, PSE treatment did not significantly affect the latency to convulsions and time until death when compared to controls. PSE exhibited anticonvulsant effects in the lithium/pilocarpine test by delaying the onset of seizures and status epilepticus as well as reducing the severity of seizures and mortality of mice. Again, the anticonvulsant effect of PSE (100mg/kg, p.o.) was blocked by pre-treatment with flumazenil in the PTZ test.

CONCLUSION

PSE has anticonvulsant activity in animal models, and this effect may be mediated, at least partly, through GABAergic mechanisms.

An evaluation of the anti-inflammatory, antipyretic and analgesic effects of hydroethanol leaf extract of Albizia zygia in animal models

CONTEXT

The leaves of Albizia zygia (DC.) J.F. Macbr. (Leguminosae-Mimosoideae) are used in Ghanaian traditional medicine for the treatment of pain, inflammatory disorders and fever (including malaria).

OBJECTIVES

The present study evaluated the anti-inflammatory, antipyretic and analgesic effects of the hydroethanol leaf extract of Albizia zygia (AZE) in animal models.

MATERIALS AND METHODS

The anti-inflammatory and antipyretic effects of AZE were examined in the carrageenan-induced foot oedema model and the baker's yeast-induced pyrexia test respectively. The analgesic effect and possible mechanisms of action were also assessed in the formalin test.

RESULTS

AZE (30-300 mg/kg, p.o.), either preemptively or curatively, significantly inhibited carrageenan-induced foot edema in 7-day-old chicks (ED₅₀ values; preemptive: 232.9 ± 53.33 mg/kg; curative: 539.2 ± 138.28 mg/kg). Similarly, the NSAID diclofenac (10-100 mg/kg, i.p.) significantly reduced the oedema in both preemptive (ED₅₀: 21.16 ± 4.07 mg/kg) and curative (ED₅₀: 44.28 ± 5.75 mg/kg) treatments. The extract (30-300 mg/kg, p.o.) as well as paracetamol (150 mg/kg, p.o.) also showed significant antipyretic activity in the baker's yeast-induced pyrexia test (ED₅₀ of AZE: 282.5 ± 96.55 mg/kg). AZE and morphine (1-10 mg/kg, i.p.; positive control), exhibited significant analgesic activity in the formalin test. The analgesic effect was partly or wholly reversed by the systemic administration of naloxone, theophylline and atropine.

CONCLUSION

The results suggest that AZE possesses anti-inflammatory, antipyretic and analgesic properties, which justifies its traditional use. Also, the results show the involvement of the opioidergic, adenosinergic and the muscarinic cholinergic pathways in the analgesic effects of AZE.

Possible mechanisms involved in the anti-nociceptive effects of hydro-ethanolic leaf extract of Ziziphus abyssinica

CONTEXT

Various parts of Ziziphus abyssinica Hochst ex. A. Rich (Rhamnaceae) have been used in Ghanaian and African traditional medicine as an analgesic. However, there are little scientific data to support the anti-nociceptive effects of the hydro-ethanolic leaf extract of Ziziphus abyssinica (EthE) as well as the possible mechanisms involved in its anti-nociceptive effects.

PURPOSE

To predict possible nociceptive pathways involved in the anti-nociceptive effects of EthE.

MATERIALS AND METHODS

The effect of EthE (30, 100 and 300 mg/kg) on intraplantar injection of pain mediators such as interleukin-1β, tumour necrosis factor-α, prostaglandin E₂ and bradykinin was evaluated in male Sprague Dawley rats using Randall-Selitto test for 5 h. The effect of specific antagonists to the opioidergic, adenosinergic, ATP-sensitive K⁺ channels, nitric oxide, serotonergic, muscarinic, adrenergic and voltage-gated calcium channel on the anti-nociceptive effect of EthE (100 mg/kg) was evaluated using the formalin test in male imprinting control region (ICR) mice for 1 h.

RESULTS

Pretreatment of the rats with EthE significantly reversed the hypernociception induced by intraplantar injection of TNF-α (F_4,120 = 10.86, p < 0.0001), IL-1β (F_4,120 = 14.71, p < 0.0001), bradykinin (F_4,80 = 12.52, p < 0.0001) and prostaglandin E₂ (F_5,144 = 6.165, p = 0.0001). The anti-nociceptive effect exhibited by EthE in the formalin test was reversed by systemic administration of N^G-l-nitro-arginine methyl ester, naloxone, theophylline and glibenclamide.

CONCLUSIONS

EthE inhibits hypernociception induced by TNF-α, IL-1β, bradykinin and prostaglandin E₂. EthE exhibited anti-nociceptive effects possibly mediated through opioidergic, adenosinergic, ATP-sensitive potassium channels and nitric oxide cyclic GMP pathways.

Anticonvulsant activity of Pseudospondias microcarpa (A. Rich) Engl. hydroethanolic leaf extract in mice: The role of excitatory/inhibitory neurotransmission and nitric oxide pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Pseudospondias microcarpa (A. Rich) Engl. is a plant used for managing various diseases including central nervous system disorders.

AIM OF THE STUDY

This study explored the anticonvulsant activity of P. microcarpa hydroethanolic leaf extract (PME) as well as possible mechanism(s) of action in animal models.

METHODS

Effects of PME was assessed in electroconvulsive (the maximal electroshock and 6-Hz seizures) and chemoconvulsive (pentylenetetrazole-, picrotoxin-, isoniazid-, 4-aminopyridine-, and strychnine-induced seizures) models of epilepsy. In addition, effect of the extract on the nitric oxide pathway and GABA_A receptor complex was evaluated.

RESULTS

The extract (30, 100 and 300mgkg^-1, p.o.) significantly delayed the onset as well as decreased the duration and frequency of pentylenetetrazole-, picrotoxin- and strychnine-induced seizures. In addition, PME pre-treatment significantly improved survival in the 4-aminopyridine- and isoniazid-induced seizure tests. Furthermore, the extract protected against 6-Hz psychomotor seizures but had no effect in the maximal electroshock test. The anticonvulsant effect of PME (100mgkg^-1, p.o.) was also reversed by pre-treatment with flumazenil, L-arginine or sildenafil. However, L-NAME or methylene blue (MB) augmented its effect.

CONCLUSION

Results show that PME has anticonvulsant activity and may probably be affecting GABAergic, glycinergic, NMDA, K⁺ channels and nitric oxide-cGMP pathways to exert its effect.

Anticonvulsant effects of antiaris toxicaria aqueous extract: investigation using animal models of temporal lobe epilepsy

BACKGROUND

Antiaris toxicaria has previously shown anticonvulsant activity in acute animal models of epilepsy. The aqueous extract (AAE) was further investigated for activity in kindling with pentylenetetrazole and administration of pilocarpine and kainic acid which mimic temporal lobe epilepsy in various animal species.

RESULTS

ICR mice and Sprague-Dawley rats were pre-treated with AAE (200-800 mg kg^-1) and convulsive episodes induced using pentylenetetrazole, pilocarpine and kainic acid. The potential of AAE to prevent or delay onset and alter duration of seizures were measured. In addition, damage to hippocampal cells was assessed in kainic acid-induced status epilepticus test. 800 mg kg^-1 of the extract suppressed the kindled seizure significantly (P < 0.05) as did diazepam. AAE also produced significant effect (P < 0.01) on latency to first myoclonic jerks and on total duration of seizures. The latency to onset of wet dog shakes was increased significantly (P < 0.05) by AAE on kainic acid administration. Carbamazepine and Nifedipine (30 mg kg^-1) also delayed the onset. Histopathological examination of brain sections showed no protective effect on hippocampal cells by AAE and nifedipine. Carbamazepine offered better preservation of hippocampal cells in the CA1, CA2 and CA3 regions.

CONCLUSION

Antiaris toxicaria may be effective in controlling temporal lobe seizures in rodents.

Hydro-ethanolic leaf extract of Ziziphus abyssinica Hochst Ex A. Rich (Rhamnaceae) exhibits anti-nociceptive effects in murine models

BACKGROUND

Despite substantial advances in pain research and treatment, millions of people continue to suffer from pain and this has been attributed mainly to the unavailability of effective and safer analgesics. The use of plants as medicines is still widespread and plants constitute a large source of novel phytocompounds that might become leads for the discovery of newer, effective and safer alternatives. Various parts of Ziziphus abyssinica have been used in folk medicine in several African countries as painkillers. However, there is no report on the possible anti-nociceptive effects of this plant especially the leaves, hence the need for this current study.

METHODS

The possible anti-nociceptive activity of hydro-ethanolic leaf extract of Ziziphus abyssinica (EthE) was assessed in rodents using chemical (acetic acid, formalin and glutamate), thermal (tail-immersion test) and mechanical/inflammatory (carrageenan) models of nociception.

RESULTS

EthE (30-300 mg/kg, p.o.) dose-dependently and significantly inhibited chemical-induced nociception with a maximum inhibition of 86.29 ± 2.27%, 76.34 ± 5.67%, 84.97 ± 5.35%, and 82.81 ± 5.97% respectively for acetic acid, formalin (phase 1), formalin (phase 2) and glutamate tests at its highest dose. EthE also dose-dependently and significantly increased reaction times in both tail-immersion and carrageenan-induced hypernociceptive tests. The activities of the extract in the various models were comparable with the effect of morphine hydrochloride and diclofenac sodium used as standard analgesic drugs.

CONCLUSION

Oral administration of hydro-ethanolic leaf extract of Ziziphus abyssinica ameliorates nocifensive behaviours associated with chemical-, thermal- and mechanical/inflammatory - induced nociceptive pain.

Effect of Trichilia monadelpha (Meliaceae) extracts on bone histomorphology in complete Freund's adjuvant-induced arthritis

AIM

This study aimed to assess the effect of petroleum ether extract (PEE), ethyl acetate extract (EthE), and ethanol extract (EAE) of Trichilia monadelpha stem bark on bone histomorphology in arthritis.

METHODS

Percentage inhibition of edema and arthritic scores in complete Freund's adjuvant-induced (0.1 ml of 5 mg/ml¹ of heat-killed Mycobacterium tuberculosis in paraffin oil-injected subplantar into the right hind paw) arthritic Sprague-Dawley rats treated with PEE, EthE, or EAE (10,30, and 100 mg/kg¹, respectively), dexamethasone (0.3-3.0 mg/kg¹), or methotrexate (0.1-1.0 mg/kg¹) over a 28-day period were estimated. Rat paws were radiographed and scored. Body weights were taken and paw tissues were harvested for histopathological studies.

RESULTS

The extracts significantly (P ≤ 0.01-0.0001) and dose dependently reduced the polyarthritic phase of arthritis. EAE and PEE significantly (P ≤ 0.01-0.0001) minimized edema spread from acute arthritic phase (days 0-10) to polyarthritic phase (days 10-28). EthE improved which deteriorated body weight in arthritis. All extracts significantly (P ≤ 0.05-0.01) improved arthritic score; reducing erythema, swelling and joint rigidity, and also significantly (P ≤ 0.05-0.01) reduced hyperplasia, pannus formation, and exudation of inflammatory cells into synovial spaces.

CONCLUSION

The stem bark extracts of T. monadelpha reduce bone tissue damage and resorption associated with adjuvant-induced arthritis, hence could be useful in managing arthritis in humans.

Albizia zygia (DC.) J.F. Macbr. (Leguminosae-Mimosoideae) root extract exhibits anti-nociceptive and antipyretic activities in murine models

ETHNOPHARMACOLOGICAL RELEVANCE

The root extract of Albizia zygia (DC.) J.F. Macbr. (Leguminosae-Mimosoideae) is traditionally used in the management of pain and fever. However, little scientific data exists in literature to support its use.

AIM OF STUDY

The present study evaluated the anti-nociceptive and antipyretic properties of the hydroethanolic extract of the roots of Albizia zygia in animal models.

MATERIALS AND METHODS

The analgesic effects were investigated in chemical (acetic acid-induced abdominal writhing and formalin tests), thermal (tail-immersion test) and mechanical (carrageenan-induced hyperalgesia) pain models. Possible mechanisms of anti-nociception were also assessed with antagonists in the formalin test. The anti-pyretic effect was evaluated using the baker yeast-induced pyrexia model in young rats.

RESULTS

The extract (30-300mg/kg, p.o.) and positive controls, diclofenac (3-30mg/kg, i.p.) and morphine (1-10mg/kg, i.p.), significantly (at least P<0.01) attenuated acetic acid-induced visceral pain, formalin- induced paw pain (both neurogenic and inflammatory), thermal pain as well as carrageenan-induced mechanical hyperalgesia in animals. The anti-nociceptive effect of the extract was reversed (at least P<0.05) by the pre-emptive administration of naloxone and atropine; the administration of theophylline, however, exhibited no significant (P>0.05) inhibition of anti-nociception. The extract (30-300mg/kg, p.o) and paracetamol (15-150mg/kg, p.o.) both reversed yeast-induced pyrexia in rats with ED₅₀ values of 48.59±2.59 and 26.19±1.33mg/kg respectively.

CONCLUSION

The findings indicate that the extract possesses significant anti-nociceptive and antipyretic effects which justify its traditional use in the management of pain and fever. Also, anti-nociceptive effect of the extract involves opioidergic and muscarinic cholinergic mechanisms.

Geraniin attenuates naloxone-precipitated morphine withdrawal and morphine-induced tolerance in mice

Background and Aim:

Potentially life-threatening and unpleasant side effects associated with some analgesics have fueled the drive for the search for more analgesics with better side effect profiles. Geraniin, the most dominant secondary metabolite in the aqueous extract of the aerial parts of Phyllanthus muellerianus, has been shown to possess antinociceptive properties mediated partly by opioidergic mechanisms. The purpose of this study is to determine whether geraniin exhibits tolerance and if it is able to ameliorate withdrawal signs in naloxone-precipitated morphine withdrawal.

Materials and Methods:

After chronic treatment of mice with geraniin orally, the formalin test was used to ascertain whether tolerance will develop to its antinociceptive effects and if there is morphine-induced tolerance cross-generalization with geraniin. The effect of geraniin on naloxone-precipitated morphine withdrawal signs in morphine-dependent mice was also investigated.

Results:

Geraniin (3-30 mg/kg) did not produce any tolerant effects after chronic administration and there was also no cross-generalization with the tolerant effects of morphine. Geraniin did not induce withdrawal signs but significantly reduced the number of jumps in morphine-dependent mice.

Conclusion:

Geraniin does not produce any tolerant effects like morphine and also reduced the signs associated with naloxone-precipitated morphine withdrawal in mice.

Anti-anaphylactic effects of Trichilia monadelpha (Thonn.) J. J. De Wilde extracts on rodent models of anaphylaxis

Effects of petroleum ether and ethanolic extracts of Trichilia monadelpha stem bark (PEE and EAE) on compound 48/80-induced systemic and passive anaphylaxis were determined. Survival rate, extravasation, degranulation of mast cells, and secretion of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were measured after pre-treatment with extracts (10-100 mg/kg) and disodium chromoglycate (2.5-250 μg/kg) and induction of anaphylaxis in C57BL/6 mice or Sprague-Dawley rats with compound 48/80. Histopathological assessments were made from skin biopsies of rats. Data was analyzed by Kaplan-Meier Survival Log-Rank Analysis, or One-way ANOVA and Holm-Sidak’s post hoc test. PEE and EAE inhibited (P ≤ 0.0001) tremors in systemic anaphylaxis passive cutaneous anaphylactic reactions and extravasation, stabilized or prevented (P ≤ 0.001-0.0001) mast cell degranulation, and inhibited (P ≤ 0.001-0.0001) TNF-α and IL-6 secretion. Per the findings, PEE and EAE of T. monadelpha have exhibited substantial anti-anaphylactic and anti-inflammatory property (with PEE performing better) which substantiates its use traditionally in management of allergies and other inflammatory disorders.

Effects of an ethanol extract and the diterpene, xylopic acid, of Xylopia aethiopica fruits in murine models of musculoskeletal pain

CONTEXT

Fruits of Xylopia aethiopica (Dunal) A. Rich. (Annonaceae) are used traditionally to manage arthritis, headache and other pain disorders.

OBJECTIVE

The analgesic properties of the X. aethiopica ethanol fruit extract (XAE) and xylopic acid (XA) were evaluated in musculoskeletal pain models.

MATERIALS AND METHODS

Acute muscle pain was induced in gastrocnemius muscle of Sprague-Dawley rats with 3% carrageenan (i.m.). Rats received XAE (30-300 mg/kg), XA (10-100 mg/kg) or morphine (1-10 mg/kg) after 12 h. Effects of XAE and XA on muscle pain were assessed by measuring post-treatment grip strength of the rats. Chronic muscle pain was similarly induced, but drug treatment was on the eighth day and effects of XAE and XA assessed with Randall-Selitto test for hyperlagesia. Acute-skeletal pain was induced in knee joints of rats with 3% carrageenan-kaolin mixture and effects determined 12-h later. Similar induction protocol was used for chronic knee pain with treatment and measurement as done for chronic muscle pain.

RESULTS

XAE and XA significantly and dose-dependently ameliorated both acute muscle (ED₅₀ mg/kg: XAE = 22.9; XA = 6.2) and skeletal hyperalgesia (XAE = 39.9; XA = 17.7) induced by 3% carrageenan. Similarly, chronic skeletal hyperalgesia was reduced by XAE and XA treatment similar to morphine (ED₅₀: XAE = 13.0; XA = 4.6). This reduction was also seen in chronic muscle hyperalgesia (ED₅₀: XAE = 79.1; XA = 42.7). XAE and XA significantly reduced the spread of hyperalgesia to contralateral limbs in both models of chronic hyperalgesia.

CONCLUSION

These findings establish analgesic properties of the ethanol fruit extract of X. aethiopica and xylopic acid in musculoskeletal pain.

Scientific evidence of plant with a rapid-onset and sustained antidepressant effect in a chronic model of depression: Mallotus oppositifolius

BACKGROUND

One of the major drawbacks of current depression pharmacotherapy is the delay in symptom improvement, aside from the untoward side effects and lack of efficacy against refractory depression. This work therefore investigated a possible rapid-onset and sustained antidepressant effect of Mallotus oppositifolius.

METHODS

Onset of the antidepressant effect of hydroalcoholic extract from the leaves of M. oppositifolius was investigated using the open space swim test, a chronic depression model. The possible effects of the extract on cognitive dysfunction measured in the Morris water maze and weight gain were also investigated.

RESULTS

M. oppositifolius extract, after the first day of treatment, reversed the state of immobility in mice. This effect was sustained even after drug treatment was halted and the antidepressant effect verified in the tail suspension test. The extract also increased the total distance travelled by the mice and reversed the cognitive impairment induced by the depressed state but had no effect on weight variation.

CONCLUSIONS

M. oppositifolius exhibits a rapid-onset and sustained antidepressant effect in mice.

Anxiolytic-like effect of the leaves of Pseudospondias microcarpa (A. Rich.) Engl. in mice

BACKGROUND

Pseudospondias microcarpa is a plant used for managing various diseases including CNS disorders. Previous studies showed sedative and anticonvulsant effects, suggesting possible anxiolytic activity. This study therefore assessed the anxiolytic effects of P. microcarpa hydroethanolic leaf extract (PME) in mice.

METHODS

In the present study, anxiolytic-like effect of the extract in behavioural paradigms of anxiety - the elevated plus maze (EPM), light/dark box (LDB), social interaction test and stress-induced hyperthermia (SIH) - was evaluated.

RESULTS

Mice treated with PME (30-300 mg kg-1, p.o.) exhibited anxiolytic-like activity similar to diazepam in all the anxiety models used. The extract increased open arm activity (p<0.05) in the EPM as well as increasing the time spent in the lit area in relation to the time spent in the dark area of the LDB. Sociability and preference for social novelty significantly (p<0.05-0.001) increased in mice treated with PME. In the SIH paradigm in mice, both PME and the benzodiazepine receptor agonist, diazepam, significantly (p<0.05) reduced the stress-induced increase in rectal temperature. The extract did not impair motor coordination and balance in the beam walk test.

CONCLUSIONS

Results of the present study indicate that PME possesses anxiolytic-like effects in mice.

Enhancement of inhibitory neurotransmission and inhibition of excitatory mechanisms underlie the anticonvulsant effects of Mallotus oppositifolius

CONTEXT

Mallotus oppositifolius is a shrub that is used traditionally to treat epilepsy, but its potential has not been scientifically validated.

AIMS

This study investigated the anticonvulsant properties and possible mechanism of action of the 70% v/v hydroalcoholic extract of the leaves of M. oppositifolius.

MATERIALS AND METHODS

Inprinting control region (ICR) mice (25-30 g) were pretreated with the M. oppositifolius leaf extract (10-100 mg/kg) before administering the respective convulsants (pentylenetetrazole [PTZ], picrotoxin [PTX], strychnine [STR], 4-aminopyridine [4-AP], and pilocarpine). The effect of the extract in maximal electroshock seizure (MES) model was investigated also.

STATISTICAL ANALYSIS

Data were presented as mean ± standard error of the mean and were analyzed with one-way analysis of variance (ANOVA) or two-way ANOVA where appropriate with Newman-Keuls or Bonferroni post hoc test respectively. P < 0.05 was considered significant.

RESULTS

In both PTX and PTZ test, extract delayed the onset of seizures and reduced the frequency and duration of seizures. In the STR-induced seizure test, the extract significantly delayed the onset of seizures and reduced the duration of seizures. The extract also delayed the onset of clonic and tonic seizures as well as increasing the survival of mice in the 4-AP-induced seizure test. It further reduced the duration of tonic limb extensions in the MES test. In the pilocarpine-induced status epilepticus, the extract significantly delayed the onset of clonic convulsions and reduced the frequency and duration of seizures. Moreover, the anticonvulsant effect of the extract was attenuated by flumazenil, a benzodiazepine/gamma-aminobutyric acid (GABA) receptor antagonist.

CONCLUSION

These findings show that the extract has anticonvulsant effect possible mediated by GABAergic, glycinergic neurotransmission, and potassium channel conductions. It may also be acting by antagonizing muscarinic receptor activation and N-Methyl-D-aspartate receptor activation.

Xylopia aethiopica fruit extract exhibits antidepressant-like effect via interaction with serotonergic neurotransmission in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Xylopia aethiopica has been used traditionally to treat some central nervous system disorders including epilepsy.

AIM OF THE STUDY

Despite the central analgesic and sedative effects, there is little evidence for its traditional use for CNS disorders. This study thus assessed the antidepressant potential of Xylopia aethiopica ethanolic fruit extract (XAE).

MATERIAL AND METHODS

Antidepressant effect was assessed in the forced swim test (FST) and tail suspension test (TST) models in mice. The role of monoamines in the antidepressant effects of XAE was evaluated by selective depletion of serotonin and noradrenaline, whereas involvement of NMDA/nitric oxide was assessed with NMDA receptor co-modulators; d-serine and d-cycloserine and NOS inhibitor, l-NAME.

RESULTS

Xylopia aethiopica (30, 100, 300mgkg(-1)) dose dependently reduced immobility in both FST and TST. The reduced immobility was reversed after 5-hydroxytryptamine (5-HT) depletion with tryptophan hydroxylase inhibitor-p-chlorophenylalanine (pCPA) and after monoamine depletion with vesicular monoamine transporter inhibitor-reserpine. The observed antidepressant effect was not affected by catecholamine depletion with the tyrosine hydroxylase inhibitor, α-methyl-p-tyrosine (AMPT). Similarly XAE did not potentiate the toxicity of a sub-lethal dose of noradrenaline. XAE had a synergistic effect with the glycineB receptor partial agonist, d-cycloserine and nitric oxide synthase inhibitor, l-NAME. However established antidepressant effects of XAE were abolished by NMDA and NOS activation with d-serine and l-arginine.

CONCLUSION

This study shows that Xylopia aethiopica has antidepressant potential largely due to effects on 5-HT neurotransmission with possible glutamatergic effect through the glycineB co-binding site and nitric oxide synthase inhibition.

An isobolographic analysis of the antinociceptive effect of xylopic acid in combination with morphine or diclofenac

Background:

A common practice of managing pain globally is the combination of analgesics and this is aimed at facilitating patient compliance, simplifying prescription, and improving efficacy without increasing adverse effects. Fruit extracts of Xylopia aethiopica are used traditionally in the management of pain disorders and xylopic acid (XA) present in the fruit extract have been shown to possess analgesic properties in animals. There is the likelihood of concomitant use of XA and the commonly used analgesics in traditional settings. This study, therefore, evaluated the pharmacologic interaction between XA/morphine and xylopic/diclofenac combinations.

Methods:

The formalin test and acetic acid writhing test were used to study the antinociceptive activity of XA, morphine, and diclofenac. The isobolographic analysis was used to study the antinociceptive interactions between XA co-administered with morphine or diclofenac.

Results:

Results obtained revealed that XA (10–100 mg/kg), morphine (1–10 mg/kg), and diclofenac (1–10 mg/kg) produced dose-related antinociception with different potencies in the formalin and acetic acid writhing tests. Isobolographic analysis of XA/morphine and XA/diclofenac combinations revealed potentiation of their antinociceptive effects. The degree of potentiation calculated as interaction index showed synergism for both combinations in all the nociceptive tests.

Conclusion:

In conclusion, the present study demonstrated synergism for the co-administration of XA with morphine or diclofenac.

Phytotherapy of experimental depression: Kalanchoe integra Var. Crenata (Andr.) Cuf Leaf Extract

CONTEXT

Kalanchoe sp. have been used since 1921 for central nervous system (CNS) disorders such as psychosis and depression. It is known to possess CNS depressant effects.

AIMS

To investigate the antidepressant properties of the aqueous leaf extract of Kalanchoe integra.

SETTINGS AND DESIGN

The study was carried out at the Kwame Nkrumah University of Science and Technology between 6 a.m. and 3 p.m.

MATERIALS AND METHODS

ICR mice were subjected to the forced swimming test (FST) and tail suspension test (TST) after they had received extract (30-300 mg/kg), fluoxetine (3-30 mg/kg), desipramine (3-30 mg/kg) orally, or water (as vehicle). In a separate experiment, mice were pre-treated with reserpine (1 mg/kg), α-methyl paratyrosine (AMPT; 400 mg/kg), both reserpine (1 mg/kg) and AMPT (200 mg/kg) concomitantly, or p-chlorophenylalanine (pCPA; 200 mg/kg) to ascertain the role of the noradrenergic and serotoninergic systems in the mode of action of the extract.

STATISTICAL ANALYSIS USED

Means were analyzed by analysis of variance (ANOVA) followed by Newman-Keuls' post hoc test. P < 0.05 was considered significant.

RESULTS

In both FST and TST, the extract induced a decline in immobility, indicative of antidepressant-like effect. This diminution in immobility was reversed by pCPA, but not by reserpine and/or AMPT. The extract increased the swimming and climbing scores in the FST, suggestive of possible interaction with serotoninergic and noradrenergic systems. In the TST, the extract produced increases in both curling and swinging scores, suggestive of opioidergic monoaminergic activity, respectively.

CONCLUSIONS

The present study has demonstrated the antidepressant potential of the aqueous leaf extract of K. integra is mediated possibly by a complex interplay between serotoninergic, opioidergic, and noradrenergic systems.

Anti-allodynic and Anti-hyperalgesic effects of an ethanolic extract and xylopic acid from the fruits of Xylopia aethiopica in murine models of neuropathic pain

Background:

Fruit extracts of Xylopia aethiopica are used traditionally in the management of pain disorders including headache and neuralgia. An animal model of vincristine-induced sensory neuropathy was developed after repeated intraperitoneal injection in rats and used in the present work to study the effects of the ethanolic extract of X. aethiopica (XAE) and its diterpene xylopic acid (XA) in vincristine-induced neuropathic pain.

Materials and Methods:

Vincristine (0.1 mg kg^-1 day^-1) was administered during two cycles of five consecutive days to induce chemotherapy-induced neuropathic pain. Static tactile anti-allodynic, anti-hyperalgesic, and cold anti-allodynic effects of XAE (30-300 mg kg^-1) and XA (10-100 mg kg^-1) were assessed using Von Frey filaments of bending forces of 4, 8, and 15 g, the Randall-Selitto paw pressure test, and cold water (4.5°C), respectively.

Results:

Administration of vincristine caused the development of allodynia and hyperalgesia with no significant motor deficit, spontaneous pain, and foot deformity. XAE (30-300 mg kg^-1) and XA (10-100 mg kg^-1) exhibited anti-hyperalgesic, tactile, and cold anti-allodynic properties with XA exhibiting greater potency than XAE. Pregabalin (10-100 mg kg^-1) used as control produced similar effect.

Conclusion:

These findings establish the anti-allodynic and anti-hyperalgesic effects of the ethanolic fruit XAE and its major diterpene XA in vincristine-induced neuropathtic pain.

Analgesic effects of stem bark extracts of Trichilia monadelpha (Thonn.) JJ De Wilde

OBJECTIVES

Various parts of Trichilia monadelpha (Thonn) JJ De Wilde (Fam. Meliaceae) are used in Ghanaian traditional medicine for the treatment of painful and inflammatory conditions. The present study examined the analgesic properties of the petroleum ether (PEE), ethyl acetate (EAE), and the hydro-ethanolic (HAE) extract of the stem bark of the plant in murine models.

MATERIALS AND METHODS

PEE, EAE, and HAE were assessed in chemical (acetic acid-induced abdominal writhing and formalin tests), thermal (hot plate test), and mechanical (Randall-Selitto paw pressure test) pain models. The possible mechanisms of the antinociceptive action were also examined with various antagonists in the formalin test.

RESULTS

HAE, EAE, and PEE, each at doses of 10-100 mg/kg orally, and the positive controls (morphine and diclofenac) elicited significant dose-dependent antinociceptive activity in the chemical (acetic acid abdominal writhing and formalin tests), thermal (hot plate test), and mechanical (Randall-Selitto paw pressure test) pain models in rodents. The antinociceptive effect of HAE was partly or wholly reversed by systemic administration of atropine, naloxone, and glibenclamide. The antinociceptive effects of EAE and PEE were inhibited by atropine.

CONCLUSION

The extracts HAE, EAE, and PEE caused dose-related antinociception in chemical, thermal, and mechanical models of pain in animals. The mechanism of action of HAE involves an interaction with muscarinic cholinergic, adenosinergic, opioidergic pathways, and ATP-sensitive K+ channels while that of EAE and PEE involve the muscarinic cholinergic system.

Analgesic effects of an ethanol extract of the fruits of Xylopia aethiopica (Dunal) A. Rich (Annonaceae) and the major constituent, xylopic acid in murine models

Background:

Fruit extracts of Xylopia aethiopica are used traditionally in the management of pain disorders including rheumatism, headache, colic pain, and neuralgia. Little pharmacological data exists in scientific literature of the effect of the fruit extract and its major diterpene, xylopic acid, on pain. The present study evaluated the analgesic properties of the ethanol extract of X. aethiopica (XAE) and xylopic acid (XA), in murine models.

Materials and Methods:

XAE and XA were assessed in chemical (acetic acid-induced abdominal writhing and formalin tests), thermal (Tail-flick and Hargreaves thermal hyperalgesia tests), and mechanical (Randall-Selitto paw pressure test) pain models.

Results:

XAE and XA exhibited significant analgesic activity in all the pain models used. XAE (30-300 mg kg^-1, p.o.) and XA (10-100 mg kg^-1, p.o.) inhibited acetic acid-induced visceral nociception, formalin- induced paw pain (both neurogenic and inflammatory), thermal pain as well as carrageenan-induced mechanical and thermal hyperalgesia in animals. Morphine (1-10 mg kg^-1, i.p.) and diclofenac (1-10 mg kg^-1, i.p.), used as controls, exhibited similar anti-nociceptive activities. XAE and XA did not induce tolerance to their respective anti-nociceptive effects in the formalin test after chronic administration. Morphine tolerance did not also cross-generalize to the analgesic effects of XAE or XA.

Conclusions:

These findings establish the analgesic properties of the ethanol fruit extract of X. aethiopica and its major diterpene, xylopic acid.

Anticonvulsant and related neuropharmacological effects of the whole plant extract of Synedrella nodiflora (L.) Gaertn (Asteraceae)

Purpose:

The plant Synedrella nodiflora (L) Gaertn is traditionally used by some Ghanaian communities to treat epilepsy. To determine if this use has merit, we studied the anticonvulsant and other neuropharmacological effects of a hydro-ethanolic extract of the whole plant using murine models.

Materials and Methods:

The anticonvulsant effect of the extract (10–1000 mg/kg) was tested on the pentylenetetrazole-, picrotoxin-, and pilocarpine-induced seizure models and PTZ-kindling in mice/rats. The effect of the extract was also tested on motor coordination using the rota-rod.

Results:

The results obtained revealed that the extract possesses anticonvulsant effects in all the experimental models of seizures tested as it significantly reduced the latencies to myoclonic jerks and seizures as well as seizure duration and the percentage severity. The extract was also found to cause motor incoordination at the higher dose of 1000 mg/kg.

Conclusions:

In summary, the hydro-ethanolic extract of the whole plant of S. nodiflora possesses anticonvulsant effects, possibly through an interaction with GABAergic transmission and antioxidant mechanisms and muscle relaxant effects. These findings thus provide scientific evidence in support of the traditional use of the plant in the management of epilepsy.

Antiarthritic and antioxidant effects of the leaf extract of Ficus exasperata P. Beauv. (Moraceae)

Leaf extracts of Ficus exasperata P. Beauv. (Moraceae) are commonly used in Ghanaian traditional medicine for the treatment of several pathological states including inflammatory disorders. The present study was undertaken to evaluate the antiarthritic effect of an ethanolic extract of F. exasperata (FEE) in the Freund's adjuvant-induced arthritis model in rats. Since free radicals and reactive oxygen species are implicated in inflammatory joint diseases such as rheumatoid arthritis, the antioxidant potential of the extract was investigated in in vitro experimental models. FEE as well as the positive controls, dexamethasone and methotrexate, showed significant dose-dependent antiarthritic properties when applied to established adjuvant arthritis. Oral administration of FEE (30-300 mg/kg p.o.) significantly reduced the arthritic edema in the ipsilateral paw of rats with a maximal inhibition of 34.46 ± 11.42%. FEE (30-300 mg/kg p.o.) also significantly prevented the spread of the edema from the ipsilateral to the contralateral paws indicating inhibition of systemic spread. The disease-modifying antirheumatic drug methotrexate (0.1-1 mg/kg i.p.) and the steroidal anti-inflammatory agent dexamethasone (0.3-3 mg/kg i.p.) also reduced very significantly the total polyarthritic edema as well as the spread of the arthritis from the ipsilateral to the contralateral paws of the treated animals. The extract also exhibited reducing activity (EC(50) = 8.105 ± 18.49), scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH, EC(50) = 0.499 ± 0.302) and prevented lipid peroxidation (IC(50) = 1.283 ± 0.923) in rat brain homogenates. Phenols were detected in the extract. These results suggest that ethanolic extract of the leaves of F. exasperata exerts antiarthritic activity after oral administration and also has antioxidant properties which may contribute to its activity.

Antinociceptive effect of an ethanolic extract of the aerial parts of Hilleria latifolia (Lam.) H. Walt. (Phytolaccaceae)

Background:

Hilleria latifolia (Lam.) H. Walt. (Phytolaccaceae) is a perennial herb used in Ghanaian traditional medicine for the treatment of various painful conditions. Little scientific evidence exists in literature on the effect of this plant on pain.

Materials and Methods:

The present study examined the antinociceptive effect of the ethanolic extract of the aerial parts of H. latifolia in chemical (acetic acid-induced abdominal writhing, glutamate, formalin, and capsaicin tests) and thermal (tail immersion test) behavioral pain models in rodents. The possible mechanisms of the antinociceptive action were also assessed with various antagonists in the formalin test.

Results:

The H. latifolia extract (HLE) together with morphine and diclofenac (positive controls), showed significant antinociceptive activity in all the models used. The antinociceptive effect exhibited by HLE in the formalin test was partly or wholly reversed by the systemic administration of naloxone, theophylline, and atropine. Glibenclamide, ondansetron, yohimbine, nifedipine, and N^G-L-nitro-arginine methyl ester (L-NAME), however, did not significantly block the antinociceptive effect of the extract. HLE, unlike morphine, did not induce tolerance to its antinociceptive effect in the formalin test after chronic administration; morphine tolerance did not also cross-generalize to HLE. Interestingly, also, the chronic concomitant administration of HLE and morphine significantly suppressed the development of morphine tolerance.

Conclusion:

Together, these results indicate that HLE produces dose-related antinociception in several models of chemical and thermal pain, without tolerance induction, through mechanisms that involve an interaction with adenosinergic, muscarinic cholinergic, and opioid pathways.

Anti-inflammatory and antioxidant effects of an ethanolic extract of the aerial parts of Hilleria latifolia (Lam.) H. Walt. (Phytolaccaceae)

Various parts of the perennial herb Hilleria latifolia (Lam.) H. Walt. (Family: Phytolaccaceae) are used in Ghanaian traditional medicine for the treatment of several inflammatory-related disorders. The present study examined the anti-inflammatory effect of an ethanolic extract of the aerial parts of Hilleria latifolia (HLE) in acute and chronic inflammation models. Since free radicals and reactive oxygen species are implicated in inflammatory diseases, the antioxidant potential of HLE was also investigated in in vitro experimental models. HLE (10-300 mg kg(-1), p.o.), either preemptively or curatively, significantly inhibited carrageenan-induced foot oedema in 7-day old chicks. Similarly, the NSAID diclofenac (10-100 mg kg(-1), i.p.) and the steroidal anti-inflammatory agent dexamethasone (0.3-3 mg kg(-1), i.p.) dose-dependently reduced the oedema in both pre-emptive and curative treatments. In the Freund's adjuvant induced-arthritis model in rats, HLE as well as the positive controls, dexamethasone and methotrexate, showed significant anti-arthritic properties when applied to established adjuvant arthritis. HLE (10-300 mg kg(-1), p.o.) significantly reduced oedema in the ipsilateral paw of rats but failed to prevent systemic arthritic spread. The DMARD methotrexate (0.1-1 mg kg(-1), i.p.) and dexamethasone (0.3-3 mg kg(-1), i.p.) reduced significantly the total polyarthritic oedema as well as the spread of the arthritis from the ipsilateral to the contralateral paws of the treated animals. The extract (0.03-1.00 mg ml(-1)) exhibited Fe(3+) reducing activity, scavenged DPPH and prevented lipid peroxidation. These findings suggest that the extract exerts in vivo anti-inflammatory activity after oral administration and also has antioxidant properties which may contribute to its activity.