Original Article 545

Neurobehavioural and Analgesic Properties of Ethanol Bark Extract of Terminalia ivorensis A Chev. (Combrataceae) in Mice

Authors

O. A. Adeoluwa1, 2, A. O. Aderibigbe2, G. O. Agu2, F. A. Adewole2, A. T. Eduviere1, 2

Affiliations

1 

Key words ▶ analgesic ● ▶ neurobehaviour ● ▶ Terminalia ivorensis ● ▶ tranquilizer ●

Abstract



Background:  Terminalia ivorensis A. Chev (Combretaceae) is a medicinal plant used in folk medicine in the management of pain, rheumatic condition, gastroenteritis and as a tranquilizer in psychotic disorder. Objective: We evaluated neurobehavioural and analgesic properties of the ethanol bark extract of T. ivorensis (EBETI). Materials and methods:  Effects of EBETI (1.25, 2.5, and 5 mg/kg) on novelty-induced behaviours were determined using open field test. Anxiolytic effect of EBETI (1.25, 2.5, and 5 mg/kg) was assessed using hole-board and elevated-plus maze paradigms. Analgesic property of EBETI (2.5, 5, and 10 mg/kg) was evaluated using acetic acid induced writhing, formalin and tail immersion tests. The extract was administered once intraperitoneally.

Results:  The LD50 of EBETI was 173 mg/kg. EBETI (1.25, 2.5, and 5 mg/kg) significantly reduced rearing (142.3 ± 1.6, 83.5 ± 1.9, 39.3 ± 1.5) and grooming (33.8 ± 3.4, 28.4 ± 3.0, 18.2 ± 1.7) as compared with controls (180.5 ± 4.9; 52.4 ± 5.2). Treatment with EBETI (1.25, 2.5, and 5 mg/kg) significantly reduced head-dipping on hole-board (9.4 ± 2.3, 6.2 ± 1.9, 5.4 ± 2.9) as compared with control (26.8 ± 1.9). However, there was no anxiolytic effect on EPM. EBETI (2.5, 5, and 10 mg/kg) significantly inhibited abdominal constriction in writhing assay (21.8.0 ± 2.4, 12.2 ± 1.6, 5.8 ± 2.1) as compared with control (35.0 ± 1.7). Inhibition of neurogenic and inflammatory phases of formalin test was notice. However, the extract could not alter response to thermal stimulus in tail immersion test. Discussion and conclusion:  EBETI is sedative and has analgesic effect, thus supporting its folkloric use in pain management and as a tranquilizer in psychosis.

received 12.07.2014 accepted 06.10.2014 Bibliography DOI http://dx.doi.org/ 10.1055/s-0034-1394417 Published online: December 16, 2014 Drug Res 2015; 65: 545–551 © Georg Thieme Verlag KG Stuttgart · New York ISSN 2194-9379 Correspondence O. A. Adeoluwa Department of Pharmacology and Therapeutics College of Medicine and Health Sciences Afe Babalola University ­Ado-Ekiti Ekiti State Nigeria Tel.:  + 234/803/6925 173 [email protected]

Abbreviation



EBETI VEH ASA DPZ MPH

 thanol bark extract of Terminalia e ivorensis vehicle acetylsalicylic acid diazepam morphine

Introduction



Terminalia ivorensis A Chev. commonly known as Idigbo belongs to Combretaceae. It is a tall, large and straight deciduous forest tree found in Africa. The plant is widely distributed especially between Guinea and Cameroon. It is also found abundantly in South West Nigeria. Because of its importance in Cote d’Ivoire culture, it is known in many quarters as Ivory Coast almond. Other common names of T. ivorensis are; black afara,

black bark, yellow terminalia, shingle wood, brimstone wood and satin wood. It is known in French as framiré; terminalia in Spanish and mwalambe in Swahili [1]. Different cultures have used different parts of the plant for various purposes in traditional health care delivery. In other words, uses of T. ivorensis vary from one region to another. In Côte d. Ivoire, decoction of root barks of T. ivorensis is used as anti-pyretic [2]. Roots of T. ivorensis are used against the loss of voice; the stem barks are also used for their antifungal characteristic in the treatment of candidosis [3]. Zirihi [4] reported that stem barks of T. ivorensis are used against skin infections. Its effectiveness in the treatment of gastroenteritis and abdominal pains has been documented [5]. In Nigeria ethnomedicine, the plant has formed part of the treatment for syphilis, the decoction of the bark is used as lotion for sores and the ­pulverized leaves as poultice to treat burns and bruises [6]. Lawal et al. [7] has reported its use as

Adeoluwa OA et al. T. ivorensis has Analgesic Property …  Drug Res 2015; 65: 545–551

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Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, Afe Babalola University ­Ado-Ekiti, Ekiti State, Nigeria 2  Department of Pharmacology and Therapeutics, College of Medicine, University of Ibadan, Oyo State, Nigeria

546 Original Article

Materials and Methods



Collection of plant materials

Barks of T. ivorensis were collected in May 2012 at the Gambari Forest Reserve, Ibadan, Oyo state, Nigeria. The taxonomical identification and authentication of the plant was done by Ugbogu O.A. and Shasanya O.S, at the herbarium section of the Forestry Research Institute of Nigeria (FRIN), Ibadan, Nigeria. A voucher specimen with identification number 109925 was deposited and compared with the reference specimen.

Preparation of plant materials

Air-dried barks (50 g) were pulverized and soaked in 70 % ethanol (1.5 L) for 48 h. The filtrate was concentrated with a rotary evaporator to give a semisolid residue and evaporated to dryness to form solid residue. It was kept in the desiccator for further use. The dried extract was subsequently reconstituted in distilled water at appropriate concentrations for the various experiments.

Drugs and chemicals

Acetic acid (May, Baker Ltd., Dagenham, England); Formaldehyde (Griffin, George, Leics, England); Acetylsalicylic acid, (ASA) (Reckitt, Coleman Ltd., Pakistan); Morphine (Martindale Pharma®, Essex, United Kingdom), Diazepam (Hoffman-La Roche, Switzerland) and ethanol (BDH, England).

Experimental animals

Swiss male albino mice (20–25 g) used in this study were obtained from the laboratory animal centre of the College of Medicine, University of Ibadan, Nigeria. The animals were kept in well-ventilated and hygienic compartments, maintained under standard environmental conditions and fed with standard rodent pellet (Livestock Feed plc, Lagos, Nigeria) and water ad libitum. The experiments were performed after approval of the protocol by the Ethics Committee of the University of Ibadan and all efforts were made to minimize animal suffering.

Acute toxicity test

The method described by Lorke [15] was used to determine LD50, which is the index of acute toxicity. Male Swiss albino mice

(20–25 g) were used. This method involved an initial dose finding procedure, in which animals were divided into 3 groups of 3 animals each. Doses of 10, 100 and 1 000 mg/kg were administered intraperitonealy (i.p.). One dose for each group. The treated animals were monitored for 24 h for mortality and general behaviours. From the results of the above step, 4 different doses of EBETI (150, 200, 250 and 300 mg/kg) were chosen and administered i.p. respectively to 4 groups of one mouse per group. The treated animals were monitored for 24 h. The LD50 was then calculated as the geometric mean of the lowest dose showing death and the highest dose showing no death.

Behavioural Studies



Assessment of the effect of EBETI on Novelty-induced rearing (NIR) and grooming (NIG)

The behavioural profiles of albino mice under the influence of the extract were assessed singly in a white Plexiglas cage measuring (45 cm × 25 cm × 25 cm). Behavioural measurements were carried out after intraperitoneal administration of vehicle (distilled water, 10 mL/kg) to group (1) and different doses of EBETI (1.25, 2.5, and 5 mg/kg, i.p.) to groups (2, 3, and 4) into mice (n = 5). Animals were taken directly from their home cage and placed individually into an opaque Plexiglas observation chamber with only one side transparent for observation. Each animal was used only once, with the observation chamber cleaned with 70 % ethanol after each assessment to remove olfactory cue from previous animal to the other. The time of the experiment was kept constant (9.00 am–1.00 pm) daily to avoid changes in biological rhythm. The behavioural components employed in this observational analysis were rearing and grooming [16, 17]. Diazepam (2 mg/kg, i.p.) administered to group (5) served as a reference drug. Frequency of rearing episodes was quantified by using a manual counter and a stop watch. The total frequency for the 30 min of observation time was summed up for each animal. Rearing was taken as the number of times the mouse was standing on its hind limb or with its forelimbs against the wall of the observation cage or in the free air. Grooming was taken as the number of body cleaning with paws, picking of the body and pubis with mouth and face washing actions.

Assessment of the effect of EBETI on locomotor activity in the open field

Motor activity was measured in an open field apparatus consisting a white Plexiglas box (28 cm × 28 cm × 25 cm) with a painted black grid dividing the floor into 16 (7 × 7 cm) equal squares. Animals were divided into 5 groups (n = 5). Group (1) was given the vehicle (10 mL/kg, distilled water, i.p.), while groups (2, 3, and 4) received EBETI (1.25, 2.5, and 5 mg/kg, i.p.) respectively. Thirty minutes after administration of the extract, animals were placed singly in one of the corners of the box; the number of squares crossed with all 4 paws was counted for 5 min. The cage was cleaned with 70 % ethanol at intervals when the animal is removed [18]. Diazepam (2 mg/kg, i.p.) administered to group (5), served as the reference drug.

Assessment of the effect of EBETI on exploratory behaviour on the hole board apparatus

The effect of the extract on the frequency of head dipping was determined on hole board apparatus. The test is a measure of exploratory behaviour that reveals sedative activity of agents.

Adeoluwa OA et al. T. ivorensis has Analgesic Property …  Drug Res 2015; 65: 545–551

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a tranquilizer in psychotic disorder. Natives in Ghana have used bark decoction in the treatment of wounds, sores and cuts [8]. The ashes of the leaf gall (common on the tree) is mixed with the roasted bulb of Crinum, made into an ointment with fresh cow butter is rub on rheumatic and other swollen joints for relief [9]. Adewunmi et al. [10] have reported that T. ivorensis showed great promise as a trypanocidal agent. Other biological activities associated with the plant include anti-inflammatory and antiarthritis [11], antibacterial activity [12] and antioxidant activity [1]. Ekong and Idemudia [13] reported presence of terminolic, ellagic, glycirrhetic acids and quercetin in the plant. Iwu and Anyanwu [11] also reported presence of sericic acid and lonchoterpene (28-hydroxy-18α-glycirrhetinic acid) along with those earlier mentioned in the plant. The crude ethanolic extract of the plant has been found to be active against E. coli, Pseudomonas aeruginisa, and Candida albicans [14]. In view of its folkloric use in pain management and as a tranquilizer, the study was designed to investigate neurobehavioural and analgesic properties of the ethanol bark extract of T. ivorensis (EBETI) in mice.

Original Article 547

Assessment of the effect of EBETI on elevated plus maze test

The elevated plus maze test was carried out to assess for possible anxiolytic effect of the extract. The elevated plus maze is a modification of the apparatus validated for mice by Lister [20] consisting of 2 open arms (30 × 5 × 0.25 cm) and 2 closed arms (30 × 5 × 15 cm) emanating from a common central platform (5 × 5 cm). The entire apparatus is elevated to a height of 50 cm above floor level. Animals were divided into 5 groups (n = 5). Group (1) received the vehicle (distilled water, 10 mL/kg, i.p), groups (2, 3, and 4) received EBETI (1.25, 2.5, and 5 mg/kg, i.p.), while group (5) received diazepam (1 mg/kg, i.p.). At the start of the session the mouse was placed at the edge of an open arm, with its head facing the centre and allowed to explore the maze for 5 min. During this test period, the following measurements were recorded: the number of entries and the time spent in open and closed arms, and the exploratory behaviour (total number of arm entries). An entry with all feet put into one arm is defined as an arm entry in this experiment. Ethanol (70 %) was used to clean the maze after each animal, to prevent odour bias. The results were expressed as mean ratio of time spent in open arms to total time spent in both open and closed arms, (percentage of time spent in open arms); mean ratio of entries into open arms to total entries into both open and close arm entries (percentage of number of entries) and number of entries into the open arms. The Index of Open Arms Avoidance [IOAA] was determined [21] i. e., IOAA = 100 – ( % time spent in open arms +  % entries into open arms)/2.

Tail immersion test

The hot water-induced tail withdrawal reflex as a model of nociception was carried out according to the method of Janssen et al. [24]. Animals were divided into 5 groups of 5 mice each. Group (1) received distilled water (10 mL/kg, i.p.), groups (2, 3, and 4) received EBETI (2.5, 5, and 10 mg/kg, i.p.) respectively while group (5) received morphine (5 mg/kg, i.p.). Thirty minutes later, the tail of each animal (up to 5 cm) was dipped in water at 55.0 ± 0.2 °C. The time (in seconds) taken by each animal to withdraw tail clearly out of the water was taken as the reaction time to pain. The cut-off time of 10 s was used to avoid tissue damage.

Statistical analysis

The data are expressed as mean ± SEM for each treatment group. The results were analysed by One Way Analysis of Variance (ANOVA) and post hoc tests (Student’s-Newman-Keuls) were carried out to determine the source of significant mean effect. The level of significance for all tests was set at p 

Neurobehavioural and Analgesic Properties of Ethanol Bark Extract of Terminalia ivorensis A Chev. (Combrataceae) in Mice.

Terminalia ivorensis A. Chev (Combretaceae) is a medicinal plant used in folk medicine in the management of pain, rheumatic condition, gastroenteritis...
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