INTRODUCTION

Convulsion is well known to be a neuro-electrical imbalance especially in the elevated status causing muscle rhythm incomprehension depending on the affected brain center or portion, presenting  many signs and symptoms including lack of awareness; loss of consciousness; eyes rolling back in the head; face that appears red or blue; changes to breathing; stiffening of the arms, legs, or whole body; jerky movements of the arms, legs, body, or head; lack of control over movements; inability to respond among others.¹

The medical word convulsion is often referred to as seizure but it is not every epileptic seizure that can lead to convulsion, and it is not every convulsion that is caused by epileptic seizures. A wide array of phenomena may resemble epileptic seizures. Most children that are often given referral to tertiary hospitals because of “fits, faints and funny turns” do not eventually have epilepsy.² Epileptic seizure is defined as “a temporary phenomenon of signs and/or symptoms which results from an unusual immoderate or synchronous neuronal activity in the brain.³ It can happen in a person who has no diagnosis of epilepsy such as found in injury involving the head, overdose of drugs or high fever in children.³

Epilepsy can develop at any age. Approximately half of new epilepsy cases start in infancy and adolescence (mainly in early months after birth). A lot of these persons tend to undergo a decline in the severity and rate of occurrence of seizures as they advance in age.⁴ However, some studies have reported an acute surge in seizure incidence as they advance in age. For instance, almost a quarter of fresh seizure cases can occur beyond 60 years of age.⁴

About 30% of seizures relate to a clear-cut abnormality in the brain.⁵ In the other 70% of cases the brain appears normal⁵ and in these cases, genetic causes are suspected. Multiple genes are however involved, and inheritance does not follow simple Mendelian rules.⁵

Many seizures can be managed by anti-seizure medications, sometimes called anti-convulsants or anti-epileptic drugs.  Different types of seizures require different medication management.⁶ Approximately 70% of seizures is successfully controlled with one anti-epileptic medication, while the remaining 30% are thus far resistant to medications.⁷

There is therefore a serious need to explore new and effective drugs from medicinal plants which have been an important source of safe and efficacious medicines.⁸ Some plants are used among some communities in Bayelsa State to manage convulsion. Sansevieria liberica Gérôme & Labroy, belongs to the family Asparagaceae. It is commonly called Bowstring hemp or Mother-in-laws tongue and also known as “Moda” (Hausa), “Ebubage” (Igbo), and “Ijo-ikoko” (Yoruba).⁹ Artocarpus altilis (Parkinson) Fosberg belongs to the family Moraceae and it is commonly referred to as breadfruit.¹⁰ Allophylus africanus P.Beauv. of the family Sapindaceae is usually a shrub, but sometimes a tree about 10 m tall.¹¹

Ethnomedicinal uses

In Nigeria, the leaf of S. liberica is employed in ethnomedicine for treating asthma, abdominal pains, colic, diarrhea, eczema, gonorrhea, hemorrhoids, hypertension, menorrhagia, sexual weakness, snake bites and wounds of the foot, among others.¹² The intact leaf of A. altilis or its latex is employed for massaging in cases of fractures, bruises, sprains, abscesses, thrush, diarrhoea, dysentery, stomach-ache, ear infections, muscle relaxant in cases of convulsive spasms and high blood pressure.¹³ The leaf of A. africanus is used for headache, migraine, malaria (Nigeria), colic, fever (Sierra Leone), conjunctivitis (Senegal)¹¹ and convulsion (Oral report).

Biological activities

Sedative and anticonvulsant activities of the root,¹⁴ antioxidant and antimalarial,¹² antimicrobial,¹⁵ hepatoprotective¹⁶ effects have been reported for S. liberica. Antimicrobial,¹⁷ alpha glucosidase inhibitory,¹⁸ larvicidal,¹⁹ antihelmintic²⁰ and growth inhibitory²¹ activities have been reported for A. altilis. There are reports of A. africanus possessing antihepatotoxic,²² antimicrobial¹¹ and anti-protective²³ activities.

Chemical Constituents   

Screening of S. liberica for phytochemicals revealed the presence of fats and oils, flavonoids (catechin and flavone), saponins, proteins, steroids, terpenoids, tannins, carotenoids, alkaloids and glycosides.¹⁶ Artocarpus altilis contains phytoconstituents like stilbenes, arylbenzofuran, flavanone, flavones, triterpenes, sterols.²⁴ The existence of alloeudesmenol, hanocokinoside, allotaraxerolide, and alloaminoacetaldehyde, tigmastane-3β,4β-diol and pinitol were reported in A. africanus.²⁵

The objective of this study is to evaluate the anticonvulsant effects of Sansevieria liberica Gérôme & Labroy, Artocarpus altilis (Parkinson) Fosberg and Allophylus africanus P.Beauv.

MATERIALS AND METHODS

Study design and setting

The study is of an experimental type, conducted in the Pharmacognosy & Herbal Medicine and Pharmacology laboratories, both in the Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Bayelsa State, South of Nigeria.

Plant Collection and Identification

Three (3) plants (Sansevieria liberica Gérôme & Labroy, Artocarpus altilis (Parkinson) Fosberg and Allophylus africanus P.Beauv.) were sourced from Bayelsa State. Each plant sourced was identified at site by a local guide in their respective locations as presented in Table 1. Authentication of the plants was done by Dr. A.T Oladele of the Department of Forestry and Wildlife Management University of Port Harcourt, Nigeria. Voucher specimens were deposited in the Herbarium Unit of the Department of Pharmacognosy & Herbal Medicine, Niger Delta University, Wilberforce Island, Bayelsa State. The voucher specimen numbers are as presented in Table 1. The various plant parts were thereafter collected.

Table 1: Location and Collection of Plants

Extraction of plant materials

The plant materials were oven-dried at temperature between 35 and 40˚C and pulverized subsequently. The plant powder (300 g) was macerated using 50% ethanol for 72 h with periodic agitation. The filtered liquid extract was then concentrated to dryness in vacuo at 30˚C to obtain dried extracts. The percentage yield was estimated. The extracts were stored at 4˚C in a refrigerator prior to use.

Phytochemical Screening

Phytochemical screening was carried out on the crude ethanol extracts of the three plants to determine the classes of constituents each plant contains using standard procedure as described by Sofowora.²⁶

Dose Preparation

The individual doses of the plant extracts were estimated, guided by their respective LD₅₀ values ranging from 0.37 – 4.57 g/kg. Thus, three doses per plant extract with the values ranging from 200, 400, 600, 800 to 1000 mg/kg were used according to the LD₅₀ value of the affected plant extract.

Experimental Animals

Mice were sourced from the Research and Animal Breeding Unit of Pharmacology and Toxicology Department, Faculty of Pharmacy Niger Delta University, Wilberforce Island, Bayelsa State. The animals acclimatized for 7 days and were handled according to the principles of laboratory animal care as required by the National Institute of Health-NIH (publication No 85-23) guideline and procedures.²⁷ Ethical approval to carry out the work was obtained from the Ethical committee of the Department of Pharmacology and Toxicology, Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria.

Pentylenetetrazol (PTZ) Model

Pentylenetetrazol (PTZ) is a chemoconvulsant popularly employed in seizure induction.²⁸ Overnight fasted mice having free access to water until 1h before the experiment were weighed and randomly allotted into 11 groups (n = 5).

Group 1: received normal saline 10 ml/kg per ora (p.o) and served as control.

Groups 2 – 4 received 200, 400 and 800mg/kg of extract of S. liberica, respectively.

Groups 5 – 7 received 400, 800 and 1000mg of extract of A. altilis, respectively.

Groups 8 – 10 received 400, 800 and 1000mg of extract of A. africanus, respectively.

Group 11 received diazepam 5 mg/kg intraperitoneally (I.P) and served as standard. 

Pentylenetetrazol 85mg/kg (I.P) was administered to all the groups 30 min after the various treatments and the animals were observed for 30 min for the onset of convulsions (tonic- clonic, hind limb extensions). The number of animals that convulsed and the degree of protection offered by the extract were compared with those of the control and standard drug (diazepam). The delay in onset of convulsions indicated anticonvulsant activity.

Data Analysis

The results were analysed using Graph Pad Prism 7. The outcome measures are expressed as mean ± standard error of mean (SE). Mean comparisons were done using one-way analysis of variance (ANOVA), followed by multiple comparison post hoc Dunnet test. Differences between the groups were considered significant at P < 0.05.

RESULTS

Phytochemical Screening

The various plants showed relative variations in their phytochemical compositions as indicated in Table 2.

Table 2: Phytochemical constituents of the medicinal plants studied

 + indicating “positive” and – indicating “negative”

Anticonvulsant Evaluation

The anticonvulsant effects of the different plant species studied are presented in the following tables

Table 3: Onset and duration of seizure effects of S. liberica

Data showing anticonvulsant activity using ANOVA multiple comparison post hoc dunnet test. * Signifies P ˂ 0.05. NS=Normal Saline; SLE= Sansevieria liberica Extract; DZP=Diazepam; S = Second.