K. Gamaniel

Anti-inflammatory and Anti-nociceptive Effects of Sphaeranthus senegalensis

Sphaeranthus senegalensis Vaill (Asteraceae) is used in traditional medicine as a remedy for rheumatic pains and other ailments. The anti-inflammatory and anti-nociceptive activity of the aqueous extract of the whole shoot of the plant was evaluated in mice and rats. Activity of the extract against egg-albumin induced hind paw oedema was measured to evaluate the anti-inflammatory activity while the anti-nociceptive potency was evaluated using three painful stimuli viz acetic acid induced abdominal constriction and hot plate test in mice, and the formalin test in rats. Results indicated that the extract possess remarkable dose dependent anti-inflammatory activities in rats. The extract also showed anti-nociceptive activities against acetic acid induced writhing, formalin and the hot plate pain models. The effects were significant (P < 0.05) when compared with the saline control group. The results suggest the presence of a potent anti-inflammatory and anti-nociceptive principle in the extract, which support the folkloric use of the plant in relieving rheumatic pains.

Antinociceptive Activity of Zizyphus spina-christi Root Bark Extract

The antinociceptive effect of the aqueous extract of Zizyphus spina-christi root bark was investigated in mice and rats. Acetic acid-induced writhing, formalin and thermal (hot plate) tests were used. The extract (50 and 100 mg/kg, i.p.) showed a dose-dependent analgesic effect in all the tests used. Its i.p. LD50 in mice was 2236.07 mg/kg.

Antiplasmodial, analgesic, and anti-inflammatory activities of the aqueous extract of the stem bark of Erythrina senegalensis

The in vivo antiplasmodial, analgesic and anti-inflammatory properties of Erythrina senegalensis, an ornamental plant commonly used in Northern Nigeria for the treatment of fevers, was evaluated. Aqueous extracts of the stem bark of the plant was used for the study. The in vivo antiplasmodial activity of the aqueous extract against Plasmodium berghei was assessed using the suppressive and curative test procedures. Analgesic activity was assessed using the acetic acid (0.75%v/v) induced abdominal constriction, while the anti-inflammatory activity was evaluated on egg-albumin induced paw oedema in rats as a model of acute inflammation. The stem bark extract of E. senegalensis exhibited only slight antiplasmodial activity while significant (P<0.05) analgesic and anti-inflammatory effects were observed. Preliminary phytochemical analysis of the extract indicates the presence of alkaloids and glycosides.

Effect of Zizyphus spina-christi Willd aqueous extract on the central nervous system in mice

The effects of the aqueous extract of Zizypus spina-christi Willd root bark against exploratory behaviour, spontaneous motor activity (SMA), motor coordination (Rota-rod performance) and pentobarbital-induced hypnosis were investigated in mice. The extract induced a significant (P<0.05) dose-dependent reduction in exploratory behaviour and SMA when administered orally. It also prolonged pentobarbital sleeping time but failed to inhibit motor coordination (rota-rod performance) in the experimental mice. These results suggest that the extract contained some constituents that depress the central nervous system, which may not be due to neuromuscular blockade.

Evaluation of the antidiarrhoeal effects of Zizyphus spina-christi stem bark in rats.

The antidiarrhoeal effects of the methanol extract of Zizyphus spina-christi stem bark were evaluated in laboratory rodents. Studies on castor oil induced diarrhoea, intraluminal fluid accumulation, and gastrointestinal transit time were carried out. Results obtained revealed that the extract caused a dose dependent protection of rats against castor oil induced diarrhoea, decreased the intraluminal fluid accumulation and gastrointestinal transit. The intraperitoneal and oral LD(50) values were found to be 346+/-5.6 and 1200+/-41.2 mg/kg in mice. Preliminary phytochemical screening revealed the presence of glycosides, resins, saponins, and tannins. It is suggested that the extract may contain biologically active components that may be useful against diarrhoea, thereby justifying its use in ethnomedical practice as an antidiarrhoeal agent.

Studies on the use of Cassia singueana in malaria ethnopharmacy.

Cassia singueana (Family: Fabaceae) is used in northern Nigeria for the treatment of acute malaria attack. We investigated the activities of the methanol extract of the root bark of this plant against rodent plasmodia infection, nociception, pyrexia and inflammation in mice and rats. The studies were carried out using acetic acid-induced writhing, hot plate algesia, rodent plasmodia (Plasmodium berghei) in mice; formalin test, yeast-induced pyrexia and egg-albumin-induced inflammation in rats. The results showed that the extract exhibited significant antinociceptive, antipyretic and antiplasmodial activity in all the models used. Phytochemical screening of the extract revealed the presence of phenols, saponins, tannins and some traces of anthraquinones. The LD50 of the extract was established to be 847+/-30 mg/kg, i.p. in mice. The observed pharmacological activities might be the scientific basis for the folkloric use of the plant in treating acute malaria attack. The study also paves way for the possible development of it, as a phytodrug against malaria.

Antinociceptive and smooth muscle contracting activities of the methanolic extract of Cassia tora leaf.

The leaves of Cassia tora Linn. (Family: Caesalpiniaceae) were soxhlet extracted with methanol. The spasmogenic effects of the extract were evaluated on guinea pig ileum, rabbit jejunum and mice intestinal transit. Antinociceptive activity of the extract was also evaluated in the mice. The LD(50) values of the extract in mice were >2000 mg/kg i.p. and p.o. The extract contracted smooth muscles of guinea pig ileum and rabbit jejunum in a concentration-dependent manner. Atropine reversibly blocked this activity. Mepyramine also reduced the contractile amplitude due to the extract in a concentration-dependent manner. The extract increased intestinal transit in mice dose dependently. C. tora extract significantly (P<0.05) reduced the number of acetic acid induced abdominal constrictions in mice and the effect was comparable to that of aspirin (150 mg/kg i.p.). The extract also significantly (P<0.05) reduced the nociceptive response of mice to increased force (g). The effects were dose-dependent. The studies suggest that the use of C. tora, traditionally, as a purgative and in the treatment of other ailments is justifiable.

Ketamine-enhanced immobility in forced swim test: A possible animal model for the negative symptoms of schizophrenia

Schizophrenia is a chronic and highly complex psychiatric disorder characterised by cognitive dysfunctions, negative and positive symptoms. The major challenge in schizophrenia research is lack of suitable animal models that mimic the core behavioural aspects and symptoms of this devastating psychiatric disorder. In this study, we used classical and atypical antipsychotic drugs to examine the predictive validity of ketamine-enhanced immobility in forced swim test (FST) as a possible animal model for the negative symptoms of schizophrenia. We also evaluated the effects of a selective serotonin reuptake inhibitor (SSRI) on the ketamine-enhanced immobility in FST. Repeated administration of a subanaesthetic dose of ketamine (30 mg kg(-1), i.p., daily for 5 days) enhanced the duration of immobility in FST 24 h after the final injection. The effect, which persisted for at least 21 days after withdrawal of the drug, was neither observed by single treatment with ketamine (30 mg kg(-1) i.p.) nor repeated treatment with amphetamine (1 and 2 mg kg(-1) i.p., daily for 5 days). The enhancing effects of ketamine (30 mg kg(-1) day(-1) i.p.) on the duration of immobility in the FST were attenuated by clozapine (1, 5 and 10 mg kg(-1) i.p.), risperidone (0.25 and 0.5 mg kg(-1) i.p.) and paroxetine (1 and 5 mg kg(-1) i.p.). Haloperidol (0.25 and 0.50 mg kg(-1) day(-1) i.p.) failed to attenuate the ketamine-enhanced immobility in the FST. The repeated ketamine administration neither affects locomotor activity nor motor coordination in rats under the same treatment conditions with the FST, suggesting that the effects of ketamine on the duration of immobility in this study was neither due to motor dysfunction nor peripheral neuromuscular blockade. Our results suggest that repeated treatment with subanaesthetic doses of ketamine enhance the duration of immobility in FST, which might be a useful animal model for the negative symptoms (particularly the depressive features) of schizophrenia.

Anticonvulsant properties of saponins from Ficus platyphylla stem bark

Preparations of Ficus platyphylla have been used in Nigerian traditional medicine for the management of epilepsy for many years and their efficacy is widely acclaimed among the Hausa communities of northern Nigeria. The anticonvulsant properties of the saponin rich fraction (SFG) obtained from the methanol extract of F. platyphylla stem bark were studied on pentylenetetrazole-, strychnine- and maximal electroshock seizures in mice. Effects of SFG were also examined in murine models for neurological disease and on relevant in vitro targets for anticonvulsant drugs. SFG protected mice against pentylenetetrazole- and strychnine-induced seizures; and significantly delayed the onset of myoclonic jerks and tonic seizures. SFG failed to protect mice against maximal electroshock seizures at doses tested. SFG neither abolished the spontaneous discharges induced by 4-aminopyridine in a neonatal rat brain slice model of tonic-clonic epilepsy nor could it modulate chloride currents through GABA(A) receptor channel complex in cultured cortical cells. However, it was able to non-selectively suppress excitatory and inhibitory synaptic traffic, blocked sustained repetitive firing (SRF) and spontaneous action potential firing in these cultured cells. Our results provide scientific evidence that F. platyphylla stem bark may contain psychoactive principles with potential anticonvulsant properties. SFG impaired membrane excitability; a property shared by most anticonvulsants particularly the voltage-gated sodium channel (VGSC) blocking drugs, thus supporting the isolation and development of the saponin components of this plant as anticonvulsant agents.

Pharmacological Evidence Favouring the Folkloric Use of Diospyros mespiliformis Hochst in the Relief of Pain and Fever

The methanol extract of Diospyros mespiliformis was evaluated for its claimed folkloric usage in the relief of pain and fever. Antipyretic, analgesic and anti-inflammatory effects of the extract were evaluated in rats and mice. Studies were carried out on yeast-induced pyrexia in rats, acetic acid-induced writhing in mice, formalin test and egg albumin-induced anti-inflammatory activity in rats. The extract (50 and 100 mg/kg i.p.) gave a potent antipyretic effect for 100 mg/kg and significant activity (P<0.05) against all the analgesic and anti-inflammatory models used. The LD(50) of the extract was estimated to be 513.80+/-33.92 mg/kg i.p. in mice. These results provide support for the use of the plant in relieving pain and fever.