Joseph A. Anuka

Anticonvulsant activity of Carissa edulis (Vahl) (Apocynaceae) root bark extract

AIM OF THE STUDY To investigate the anticonvulsant activity of root bark extract of Carissa edulis. MATERIALS AND METHODS The median lethal dose (LD(50)) of Carissa edulis extract was determined using Lorks method (1983). The anticonvulsant activity of the extract was assessed in pentylenetetrazole (PTZ)-induced convulsion in mice and maximal electroshock test (MEST) in chicks, with benzodiazepine and phenytoin as standard drugs, respectively. While mechanistic studies were conducted using both flumazenil, a GABA(A)-benzodiazepine receptor complex site antagonist and naloxone a non-specific opioid receptor antagonist. RESULTS The median lethal dose (LD(50)) of Carissa edulis was 282.8mg/kg and over 5000mg/kg following intraperitoneal and oral administration, respectively. Carissa edulis produced 40% and 20% protection against convulsion at 5 and 20mg/kg, respectively, compared with 100% protection with benzodiazepine. The mean onset and percentage protection against convulsion in Carissa edulis extract-treated mice were reduced by flumazenil and naloxone. Carissa edulis exhibited dose-dependent inhibition of the convulsion induced by MEST with 20mg/kg providing 90% protection while phenytoin (20mg/kg) produced 100% protection. CONCLUSION These results suggest that Carissa edulis possesses biologically active constituent(s) that have anticonvulsant activity which supports the ethnomedicinal claims of the use of the plant in the management of epilepsy.

Behavioral properties of Balanites aegyptiaca in rodents.

ETHNOPHARMACOLOGICAL RELEVANCE Balanites aegyptiaca is a native plant from the dry tropical areas of Africa and Arabia. It has been used in traditional medicine to treat psychoses, epilepsy, rheumatism and for the management of cough, liver and spleen conditions for many years. The plant is also used as antihelmintic and molluscicide. AIM OF THE STUDY The present studies aimed at investigating the behavioral properties of ethanol extract of the root of this medicinal plant, which is already in common applications in the Nigerian traditional medicine. MATERIALS AND METHODS The intraperitoneal and oral mean lethal dose (LD(50)) of the extract was determined using the Lorkes method. The preliminary phytochemical screening of the extract was carried out to identify the secondary metabolites in the extract. Furthermore, the behavioral properties of the extract were evaluated using diazepam-induced sleep, open field test, staircase test and beam walking assay all in mice. RESULTS The extract significantly (p<0.001) prolonged the duration diazepam (20mg/kg i.p)-induced sleep in mice dose dependently. However, the extract showed no significant effect on the onset of diazepam-induced sleep. In the open field test, the extract (150 and 300 mg/kg) and diazepam (0.05 mg/kg) produced a significant (p<0.05, p<0.005 and p<0.001) decrease in the number of square crossings. There was no significant effect on the number of centre square crossing following the administration of the extract. The extract (75 and 150 mg/kg) and diazepam (0.05 mg/kg) produced a significant (p<0.05) decrease in the number of rearing suggestive of sedation. In the staircase experiment there was a decrease in the number of upward step climbing as well as number of rearing suggesting anxiolytic and sedative properties of the extract. In the beam walking assay the extract did not produce any significant increase in the time taken to complete task as compared to diazepam 1mg/kg which was significant at p<0.05. Furthermore, 30 mg/kg of the extract and diazepam 1mg/kg showed significant (p<0.05) mean number of foot slips, suggesting that the central nervous system depressant activity might not necessarily due to peripheral neuromuscular blockade. CONCLUSION The result indicates that the extract of Balanites aegyptiaca possess biologically active compound(s) that have anxiolytic and sedative properties, which support the ethnomedicinal use of the plant as antipsychotic and antiepileptic agents.

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.

Some Pregnancy-Related Effects of Artemether in Laboratory Animals

Artemether, highly effective in multi-drug-resistant malaria is not routinely available for use in pregnancy due to the lack of adequate research data in animals and man. This study was therefore aimed at investigating some pregnancy-related effects of artemether. Artemether (1.5, 7.5 and 15 mg/kg i.p. daily for 7 days) did not produce changes in rat oestrous cycle. The drug did not prevent or prolong the rate of conception or parturition, cause pre-term delivery and affect litter size. Birth weight and growth rate of pups from artemether-pretreated dams were within the normal range. Artemether (48–480 µg/ml) had no agonist effect on the isolated uterine smooth muscles of both non-pregnant and pregnant rats and guinea pigs. However, the drug (24– 240 µg/ml) reduced oxytocin-induced contraction of uterine tissues concentration-dependently, particularly in pregnant uteri.

Psychopharmacological properties of saponins from Randia nilotica stem bark

Abstract Context: Decoctions of Randia nilotica Stapf. (Rubiaceae) have been used in the Nigerian traditional medicine for the management of epilepsy, anxiety, depression and psychosis for many years and their efficacies are widely acclaimed among the rural communities of Northern Nigeria. Objective: The aim of this study is to establish whether the saponins present in R. nilotica are responsible for its acclaimed beneficial effects in Nigerian traditional medicine. Materials and methods: The behavioural properties of the saponin-rich fraction (SFRN) of R. nilotica stem bark were studied on hole-board, diazepam-induced sleep, rota-rod and beam-walking in mice. The anticonvulsant properties of SFRN were also examined on maximal electroshock, pentylenetetrazole- and strychnine-induced seizures in mice. Results: The intraperitoneal LD50 of SFRN in mice and rats were estimated to be 11.1 and 70.7 mg/kg, respectively. SFRN significantly prolonged the duration of diazepam-induced sleep; diminished head dip counts in the hole-board test and protected mice against maximal electroshock seizures. SFRN failed to protect mice against pentylenetetrazole- and strychnine-induced seizures; and had no effect on motor coordination on the rota-rod treadmill at the doses tested. SFRN significantly decreased the number of foot slips in the beam-walking assay in mice with no effect on time to reach the goal box. Discussion and conclusion: This study provides evidence of the psychopharmacological effects of SFRN, thus supporting further development of the psychoactive components as remedies for epilepsy.

Safety assessment of the standardized extract of Carissa edulis root bark in rats

ETHNOPHARMACOLOGICAL RELEVANCE Preparations of Carissa edulis (Vahl) have been used in the Nigerian traditional medicine for the management of fever, sickle cell disease, epilepsy, pain and inflammation for many years and their efficacy is widely acclaimed among the Hausa communities of northern Nigeria. AIM OF THE STUDY The present studies aimed at evaluating the toxicological properties of the standardized ethanol extract of C. edulis root bark in rats, in order to determine its safety and to complement earlier efficacy studies on this widely used medicinal plant. MATERIALS AND METHODS High performance liquid chromatography (HPLC) and preliminary phytochemical analysis of the extract were conducted and its oral median lethal dose (LD50) determined. Signs of toxicity, body weight changes, relative organs weight, feed and water consumption were monitored following 28 days of daily oral administration of graded doses of the extract in rats. Effects of the extract on sex hormones, low- and high-density lipids, hematological and biochemical parameters were examined and pathological changes of the vital organs after treatment with the extract were also investigated. RESULTS The oral LD50 of the extract was estimated to be >5000 mg/kg. The body weights of treated rats increased progressively, but the changes were not significantly different from the control groups. The extract neither produces significant changes in feed and water consumption nor affected the relative organs weight. Although some variations were observed in hormonal and lipid profiles hematological and biochemical indices, these important parameters were normal and within acceptable limits. No lesions or pathological changes of the organs attributable to treatment with the extract were observed from the pathological examinations. The HPLC fingerprint of the extract shows a spectrum profile characteristic of C. edulis, while the preliminary phytochemical screening revealed the presence of saponins, flavonoids, tannins, anthraquinones and cardiac glycosides. CONCLUSION Our results provided evidence that short-term administration of the standardized ethanol extract of C. edulis root bark at doses lower than 1000 mg/kg is safe in rats and may not exert severe toxic effects.

Central depressant activity of butanol fraction of Securinega virosa root bark in mice

ETHNOPHARMACOLOGICAL RELEVANCE Securinega virosa is a commonly used medicinal plant in African traditional medicine in the management of epilepsy and mental illness. Previous studies in our laboratory showed that the crude methanol root bark extract of the plant possesses significant behavioral effect in laboratory animals. In an attempt to isolate and characterize the biological principles responsible for the observed activity, this study is aimed at evaluating the central depressant activity of the butanol fraction of the methanol root bark extract of Securinega virosa. MATERIALS AND METHODS The medial lethal dose of the butanol fraction was estimated using the method of Lorke. Preliminary phytochemical screening was conducted on the butanol fraction using standard protocol. The behavioral effect of the butanol fraction (75, 150 and 300mg/kg) was evaluated using diazepam induced sleep test, hole-board test, beam walking assay, staircase test, open field test and elevated plus maze assay, all in mice. RESULTS The median lethal dose of the butanol fraction was estimated to be 1256.9mg/kg. The preliminary phytochemical screening revealed the presence of tannins, saponins, alkaloids, flavonoids, cardiac glycosides, similar to those found in the crude methanol extract. The butanol fraction significantly (P<0.001) reduced the mean onset of sleep in mice and doubled the mean duration of sleep in mice at the dose of 75mg/kg. The butanol fraction and diazepam (0.5mg/kg) significantly (P<0.01-0.001) reduced the number of head dips in the hole-board test suggesting sedative effect. The sedative effect of the butanol fraction was further corroborated by its significant (P<0.01-0.001) reduction of the number of step climbed and rearing in the staircase test. The butanol fraction did not significantly increase the time taken to complete the task and number of foot slips in the beam walking assay, suggesting that it does not induce significant motor coordination deficit. Diazepam (2mg/kg), the standard agent used significantly (P<0.01) increased the number of foot slips. In the open field test, the butanol fraction significantly reduced the number of square crossed as well as the number of rearing. However, the butanol fraction did not significantly alter the behavior of mice in the elevated plus maze assay, while diazepam (0.5mg/kg) significantly (P<0.05) increased the time spent in the open arm and reduced the number of closed arm entry. CONCLUSION The findings of this study suggest that the butanol fraction of Securinega virosa root bark contains some bioactive principles that are sedative in nature.

The effect of methanol rhizome extract of Nymphaea lotus Linn. (Nymphaeaceae) in animal models of diarrhoea

ETHNOPHARMACOLOGICAL RELEVANCE Nymphaea lotus, which is widely distributed throughout tropical Africa, enjoys a number of ethnomedical uses in Nigeria. Traditionally, the rhizomes of N. lotus are used to cure diarrhoea. AIM OF STUDY This study aims to evaluate the antidiarrhoeal activity of the methanol rhizome extract of N. lotus plant in laboratory animals. MATERIALS AND METHODS The extract was screened for activity against castor oil-induced diarrhoea and magnesium sulphate-induced diarrhoea as well as effect on gastric transit time in mice. The effect of methanol rhizome extract of Nymphaea lotus on the perfused isolated tissue preparation was also determined. RESULTS For castor oil-induced diarrhoea, the extract at doses of 200, 400 and 800mg/kg produced significant reduction in the frequency of diarrhoea (at p<0.001, p<0.001 and p<0.01 respectively). The extract at 800mg/kg produced a significant delay in onset of diarrhoea (p<0.05) comparable to loperamide (3mg/kg). The frequency of magnesium sulphate-induced diarrhoea was also significantly reduced in the groups treated with 200, 400 and 800mg/kg of the extract at p<0.001, p<0.001 and p<0.01 respectively. At doses of 200mg/kg and 400mg/kg, the protection produced was comparable to loperamide, 3mg/kg. All treated groups produced significant reduction in the transit of charcoal meal along the intestinal tract at p<0.001. The extract at low concentration (4×10(-4)-6.4×10(-2)mg/ml) had contractile effect on the tone of contraction of the rabbit jejunum while at higher concentrations (8×10(-2)-512×10(-2)mg/ml) produced significant reduction in the tone and rate of spontaneous contraction of rabbit jejunum. The extract at lower concentrations (4×10(-4)-2×10(-2)mg/ml) has no effect on contraction of the guinea pig ileum while higher concentrations (4×10(-2)-512×10(-2)mg/ml) produced significant relaxant activity on guinea pig ileum. CONCLUSION This study has shown that the methanol rhizome extract of N. lotus has antidiarrhoeal properties thus justifying its use by the local population for this purpose.

Histopathological effects of sub-chronic lamivudine-artesunate co-administration on the liver of diseased adult Wistar rats

Background: Lamivudine and artesunate are sometimes co administered in HIV-malaria co morbidity. Both drugs are used concurrently in presumptive malaria treatment and simultaneous HIV post exposure prophylaxis. Aim: The aim of this study was to investigate the effect of lamivudine-artesunate co administration on the histology of the liver of diseased adult Wistar rats. Materials and Methods: Five groups of rats of both sexes were used for the study and placed on feed and water ad libitum. Disease state consisted of immunosuppression with cyclophosphamide, and infection with Plasmodium berghei. Group 1 animals served as vehicle control, while group 2 were the diseased controls. Group 3 animals received 20 mg/kg lamivudine for three weeks, while group 4 similarly received 20 mg/kg Lamivudine but also received 10 mg/kg artesunate from day 12. Animals in group 5 received 10 mg/kg artesunate from day 12. All drugs were administered intraperitoneally. The animals were treated for twenty-one days, at the end of which they were sacrificed and their livers fixed in 10% formalin for histological studies. Result: Results from the study show the presence of regions of focal necrosis and perivascular cuffing with animals that received artesunate. Hemosiderosis was a common feature in all the parasitized groups, while fatty degeneration was observed in the group that received artesunate alone. Conclusion: Concurrent lamivudine-artesunate administration resulted in some histopathological changes in the liver. This study suggests there may be considerable histological changes with repeated occurrence of malaria and immunosuppression that may warrant intermittent lamivudine-artesunate administration, and may require evaluation as well as monitoring of liver function during such therapeutic interventions.

Histopathological effects of artemether on selected organs in rat

Dose and treatment-duration neurotoxic effects are reported for artemisinin drugs of mostly the liposoluble derivatives; and yet artemether, the only parenteral formulation of the artemisinin series available in Nigeria is fat-soluble and also has a treatment-duration of 5–7 days (in an attempt to delay recrudescence). Since parenteral drugs are usually resorted to in severe/complicated or multidrug-resistant malaria against the oral artemisinin co-formulated therapies (ACT), this study is aimed to investigate the pathological changes on selected tissues (if any), in rats, of the normal 7-days artemether-injections when used both in the normal and higher doses. Artemether was administered i.p., at three dose levels, equivalent to therapeutic dose (1.5 mg kg−1) as well as 5 and 10 times higher (7.5 and 15 mg kg−1). A three percentage v/v Tween 80 vehicle was used for the control experiment. The pathological changes in the kidney, heart, liver, and lungs evaluated using percentage mean organ:body-weight ratio showed no changes in the organs. No histopathological effect was observed in the organs of rats treated with 1.5 mg kg−1. However, rats treated with 7.5 and 15 mg kg−1 revealed necrositic lesions with mononuclear cellular-infiltration in the liver and brain. The liver had focal area necrosis, while the brain had liquefactive necrosis, neuronal degeneration, congested blood vessels, hemorrhage, and vacuolations. The interstitial spaces of the glomerulus and renal tubules of one kidney from rats that received 15 mg kg−1 had focal area fibrositic-necrosis.