ANTI-DIARRHOEAL ACTIVITIES of AQUEOUS STEM BARK EXTRACT of AMBLYGONOCARPUS ANDONGENSIS (WELW.EX OLIV.) EXELL & TORRE Ugwah

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ANTI-DIARRHOEAL ACTIVITIES OF AQUEOUS STEM BARK EXTRACT OF AMBLYGONOCARPUS ANDONGENSIS (WELW.EX OLIV.) EXELL & TORRE

Ugwah, O. M.1, Ugwah-Oguejiofor, C. J. 2*, Abubakar, K.2, Okorie, N. A.3, Njan, A. A.4

1Department of Pharmacology, College of Health Sciences, Usmanu Danfodiyo University, P.M.B. 2346 Sokoto, Sokoto State, Nigeria. 2Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, Usmanu Danfodiyo University, P.M.B. 2346 Sokoto, Sokoto State, Nigeria. 3Department of Pharmacology & Toxicology, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka 410001, Enugu State, Nigeria. 4Department of Pharmacology and Therapeutics, Faculty of Basic Medical Sciences College of Health Sciences, University of Ilorin, Kwara State, Nigeria. *Author for correspondence: [email protected]; +234 803 609 824

ABSTRACT

Amblygonocarpus andongensis (Welw.ex Oliv.) Exell & Torre is used extensively in Sokoto state, Nigeria for the treatment of diarrhoea, pain and psychosis. The aim of this study was to evaluate the anti-diarrhoeal properties of aqueous extract of stem bark of Amblygonocarpus andongensis in Wistar rats. The aqueous extract (200, 400 and 600 mg/kg, p.o. in rats) was evaluated for anti-diarrhoeal properties against castor oil-induced, gastrointestinal motility and prostaglandin E2 (PE2)-induced enteropooling models of anti-diarrhoeal studies in Wistar rats. Isolated Guinea-pig ileum was used to evaluate the antispasmodic effect of the plant extract. The parameters observed were the total number of diarrhoea faeces and the onset of the production of the faeces in the castor oil-induced model; the distance travelled by charcoal meal in the gastrointestinal motility test; the volume of intestinal content in PE2-induced enteropooling assay; and the length of contraction exerted on the isolated guinea-pig ileum in the antispasmodic experiment. The extract significantly (p< 0.001) reduced faecal output and delayed the onset of defecation against the castor oil-induced diarrhoea. It also significantly (p< 0.001) inhibited the propulsion of charcoal meal in the gastrointestinal motility test. Similarly, the extract at all dose levels significantly reduced the volume of intestinal content against PE2-induced enteropooling assay. The extract (1, 2, 4, 8 and 16 mg/ml) also exerted a significant (p<0.001) inhibitory response on acetylcholine- induced smooth muscle contraction in the isolated Guinea-pig ileum. It demonstrated anti-diarrhoeal properties which may be due to its anti-motility/antispasmodic and anti-secretory effects. These therefore lend pharmacological credence to its folkloric use in the treatment of diarrhoea.

Key words: Amblygonocarpus andongensis; acute toxicity; Anti-diarrhoeal activity; guinea-pig ileum; Enteropooling; Castor-oil

INTRODUCTION developing countries like Nigeria, it constitutes a major health challenge with Diarrhoea is one of the most common high prevalence in children and infants gastrointestinal disorders, characterized by (Audu et al., 2000). Amongst the an increase in frequency and production of developed countries, it is still a significant watery stool (Farthings, 2002). In most health issue regardless of their more stable

Ugwah et al., Nig. Journ. Pharm. Sci., September, 2014, Vol. 13 No.2, P 01-11 public health and economic wealth andongensis (Welw.ex Oliv.) Exell & (Casburn-Jones and Farthing, 2004). Torre. All these are synonyms of the According to the world health organisation accepted plant name Amblygonocarpus (WHO) report, it is estimated that andongensis (Welw.ex Oliv.) Exell & diarrhoea causes 4–5 million deaths Torre. annually throughout the world. Eighty percent of these deaths are reported in Amblygonocarpus andongensis is a developing countries including Nigeria deciduous tree commonly distributed (Yilgwan and Okolo, 2012). throughout tropical Africa (Burkill, 1985). Various types of drugs are available for the It is usually 30–40 feet high, but reaching treatment of diarrhoea. Such drugs are 60 feet and 5 feet girth in moist areas. It is anti-motility agents (atropine, loperamide commonly known as Scotsman’s rattle, hydrochloride, and codeine), adsorbents ‘Kolo’ in Hausa and ‘jigaree-hi’in Fulfude (activated charcoal, kaolin, and languages of Nigeria. The root decoction is cholestyramine), antibiotics and many usually administered as an emetic to treat others. These drugs even though they are food poisoning. It is also used against colic effective for the management of this and cough and as a vermifuge. The disorder, they suffer from many side decoction of the stem bark is used as an effects such as headache, dry mouth, antidote for snakebites and can be applied rashes, fever, and severe allergic reactions to sores. The stem bark can also be (Sharma and Sharma, 2007). Hence, there macerated and used to treat diarrhoea is always a continuous need to search for a (Burkill, 1995) and breast cancer safer alternative to these available drugs. (Kubmarawa et al., 2007). The leaf extract is used to treat stomach-ache and the In developing countries, majority of the powdered pods to treat ulcers. people depend on traditional medicine in treating all kinds of diseases including The plant has been previously evaluated diarrhoea (Lin et al., 2002). The WHO has for its use in the treatment of pain (Nwiyi, encouraged scientific studies for the et al., 2006) and psychosis (Ebboh, et al., treatment and prevention of diarrhoeal 2010). In Sokoto, the use of this plant for disease based on traditional practice the treatment of diarrhoea has continued because of fewer side effects associated without scientific evidence. Therefore, the with it. Many studies have justified the aim of this study is to evaluate the anti- traditional use of anti-diarrhoeal medicinal diarrhoeal activity of aqueous stem bark plants by evaluating the biologic activity extract of Amblygonocarpus andongensis of extract of such plants which have using castor oil-induced diarrhoeal model, antispasmodic effects, suppress gastrointestinal (GI) motility test, gastrointestinal motility, stimulate water Prostaglandin E2 (PGE2)-induced adsorption or reduce electrolyte secretion enteropooling assay in Wistar rats and (Palombo, 2006). antispasmodic studies using isolated Among the medicinal plants with guinea-pig ileum. therapeutic potentials, the genus ‘Amblygonocarpus’ is of great importance. 2. MATERIALS AND METHODS Amblygonocarpus is a genus of flowering 2.1. Drugs and chemicals plants in the legume family, Fabaceae Castor oil (Bell Sons and Co., England), belonging to sub family Mimosoideae. It Charcoal meal (10% activated charcoal in is a genus of one species in tropical Africa 100 ml of 5% aqueous gum acacia), and contains plants species names as Acetylcholine and Atropine Sulphate obtusangulus Harms (Tetrapleura (Sigma Chemicals, USA), Loperamide obtusangula), schweinfurthii Harms and (Janssen, England).

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2.2. Plant material Sokoto. The care and handling of the The plant material (stem barks of A. animals were in accordance with the andongensis) was obtained from Kara Animal Research Regulation 1985-2010 Market area in Sokoto North Local and the Organisation of Economic government Area of Sokoto State, Nigeria Development (OECD) guidelines on good in the month of August and was identified laboratory practice (OECD, 2008). by Dr. Halilu E. Mshelia, a taxonomist in the Department of Pharmacognosy and 2.5. Phytochemical studies Ethnopharmacy, Usmanu Danfodiyo The phytochemical evaluation of aqueous University, Sokoto. The plant material was extract of stem bark of A. andongensis was stored in the herbarium of the same carried out using the methods described by department with a voucher number Trease and Evans (1983) and as modified Pcg/UDUS/Mimo/006. by El-Olemmy et al. (1994) and Harbone (1993). The presence of alkaloids, 2.3. Preparation of plant material glycosides, tannins, saponins, terpenoids, The stem bark of A. andongensis was flavonoids, saponins glycosides, cardiac washed with tap water, cut into smaller glycosides, anthraquinones, volatile oil, sizes and air dried under the shade to a and steroids were tested. constant weight. The dried stem barks were pulverised mechanically into a dry 2.6. Oral acute toxicity study powder using a grinding machine. 300 g of The oral acute toxicity study was tested the powdered plant material was using ‘Up-and- Down’ method at a limit macerated in 4.5 litres of distilled water for dose of 3000 mg/kg in healthy adult 24 hours with constant stirring. The female rats according to ‘OECD’ guideline resulting aqueous crude extract was no. 425 (OECD, 2001). Five female rats evaporated to dryness using a hot air oven were randomly selected through a at 45 ± 1oC. A brownish powdery extract computer generated random numbers and of percentage yield of 9.4% was realised. labelled with picric acid for identification. It was this extract that was dissolved in An animal was picked at a time, weighed distilled and administered orally to the rats and dosed orally with 3000 mg/kg body of according to the required dose. the extract after 18 h fasting. Each animal was observed after dosing for the first 5 2.4. Animals minutes for signs of regurgitation and kept Wistar rats (Rattus norvergicus) of either in a metallic cage. Then, they were sex (180- 200 g) were obtained from Mike observed every 15 minutes in the first 4 h, Ugwah animal house in the Usmanu every 30 minutes for 6 h and daily for 48 Danfodiyo University Teaching Hospital, hours for short-term outcome according to Sokoto. Guinea pigs (500-600 g) were the specifications of OECD. The animals acquired from the animal facility centre of were monitored for a total of 14 days for the University of Nigeria, Nsukka. The long-term possible lethal outcome. animals were housed in standard cages and were allowed for 1 week for acclimatisation to our laboratory condition 2.7. Anti-diarrhoeal evaluation before the commencement of the study. 2.7.1. Castor oil-induced diarrhoea in rats Standard commercial chow and water were The Castor oil-induced diarrhoea was provided ad libitium. Housing conditions conducted according to the method of were maintained at 25 ± 2oC at 12 h day/ Havagiray et al. (2004). Twenty five night cycles. The study was approved by wistar rats were fasted for 18 h and divided the Animal Research Ethics Committee of into five groups of 5 animals per group. the Usmanu Danfodiyo University, Groups 1-3 represented the plant extract

Ugwah et al., Nig. Journ. Pharm. Sci., September, 2014, Vol. 13 No.2, P 01-11 groups (200, 400 and 600 mg/kg p.o), Groups 1-3 represented the plant extract group 4 represented the reference drug groups (200, 400 and 600 mg/kg p.o), group (loperamide 2.5 mg/kg, p.o.) while group 4 represented the reference drug group 5 represented the vehicle control group (loperamide 2.5 mg/kg, p.o.) while group (normal saline 1 ml/kg, p.o.). Food group 5 represented the vehicle control was withdrawn throughout the period of group (normal saline 1 ml/kg, p.o.). After study but water was provided ad libitium. 1 h, 100 µg/kg of PGE2 was administrated After 1 h of drug pre-treatment, each orally to all rats to induce enteropooling. animal was fed orally with 1 ml of castor Thirty minutes after the administration of oil. The animals were kept in separate the PGE2, all rats were sacrificed and the metabolic cages with a plain sheet of paper whole lengths of intestines from pylorus to placed on the floor to collect their the caecum were dissected. The contents droppings. They were observed every hour of the intestines were collected and the for 4 h after castor oil administration. The total volume measured. onset of the production of the faeces and the total number of diarrhoea faeces were 2.8. Isolated guinea-pig ileum noted. The results were expressed as a experiment percentage of diarrhoea inhibition. The guinea pig was fasted for 18 h before Percentage of diarrhoea inhibition = (T0 – the experiment. After the animal was T1 / T0) * 100 sacrificed, the midline incision of the T0 = number of wet faeces in vehicle abdomen was made and the ileum was control group isolated. The ileum was cut into strips of 2 T1 = number of wet faeces in test group cm long. A piece of ileum was mounted in a bath of 20 ml Tyrode’s solution (NaCl = 2.7.2. Gastrointestinal motility tests 8.0, KCl = 0.2, MgCl2 = 0.1, CaCl2 = 0.2, Rats fasted for 18 h were divided into five NaH2PO4 = 0.05, NaHCO3 = 1.0, and groups of 5 animals each. Groups 1-3 glucose = 1 g/L) with a controlled represented the plant extract groups (200, temperature of 37oC and aerated with 95% 400 and 600 mg/kg p.o), group 4 O2 and 5% CO2. Isometric concentrations represented the reference drug group that were recorded under a resting tension of 1 received atropine sulphate (0.1 mg/kg i.p. g via a force displacement transducer and per rat) and group 5 represented the displayed on a polygraph (Ugo basile). vehicle control group that received After an equilibration period of 30 min, aqueous suspensions of acacia (1 ml p.o. standard contractions produced by per rat). Thirty minutes after the pre- acetylcholine (ACh) (2, 4, 8, and treatment, 1 ml of charcoal meal (10% 16ug/mL) were recorded. The tissue was charcoal suspension in 5% gum acacia) then washed out with Tyrode’s solution. was administered orally to each rat. The To test the inhibitory effect, the extract (1, rats were sacrificed 1 h later and the 2, 4, 8 or 16 mg/ml) was added into the intestine was removed from pyloric organ-bath 3 minutes before the addition sphincter to caecum. The distance travelled of 8 ug/ml of ACh (which gave 16 mm by charcoal meal from the pylorus was response and taken as 100% response). measured and expressed as percentage of The responses were noted. The same the total length of the intestine (Mascolo et procedure was repeated using atropine al., 1994). sulphate (1, 2, 4, 8 or 16 ug/mL). The tissue was further washed 3-4 times after 2.7.3. PGE2 induced enteropooling test measuring the contractions at each dose of The method of Robert et al. (1976) was test substances. adopted. Rats fasted for 18 h were divided into five groups of 5 rats per group.

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The percentage responses were calculated 3.2. Acute toxicity study (Department of Pharmacology, University There was no regurgitation or any obvious of Edinburg, 1970). behavioural sign of toxicity in the animals according to the specification of OECD. 2.9. Statistical Analysis There was also no mortality recorded at The data were analysed using Graph Pad oral limit dose of 3000 mg/kg body Prism version 6 software. The results of weight. the study are expressed as the mean (%) ± S. E. M. Comparison in all the groups was 3.3. Anti-diarrhoea evaluation made using one-way analysis of variance 3.3.1. Effect of aqueous extract of stem (ANOVA) followed by Student’s t- tests. bark of Amblygonocarpus andongensis on Differences were considered to be castor oil-induced diarrhoea in rats significant at p< 0.05. In the castor oil-induced diarrhoea experiment, the extract treated rats 3. RESULTS produced dose-related, significant reduction in the production of diarrhoea 3.1. Phytochemical analysis faeces. The loperamide group was similar Phytochemical analysis of the aqueous to 600 mg/kg extract group. Treatment stem bark extract of A. andongensis with A. andongensis increased the revealed the presence of tannins, saponins, percentage inhibition of diarrhoea and flavonoids, steroids, alkaloids, glycosides, delayed the onset of defecation compared terpenes, cardiac glycosides and saponins with the vehicle control group (Table 1). glycosides.

Table 1: Effect of aqueous extract of stem bark of Amblygonocarpus andongensis on onset of defecation time and the mean number of faeces in castor oil-induced diarrhoea in rats Treatment Onset of faeces (min) Mean number of % of diarrhoea diarrhoea faeces inhibition

200 mg/kg Aa 105±9.55** 5.87±1.72* 42.62 400 mg/kg Aa 150±7.13** 3.48±0.31** 65.98 600 mg/kg Aa 210±7.33** 0.93±1.34*** 90.91 Loperamide 215±9.89 0.45±1.02*** 95.6 Control (vehicle) 27±6.67 10.23±1.22 0 Data presented as mean%± SEM, n= 5 for all groups. *p<0.05, **p< 0.01, ***p<0.001 compared with vehicle (normal saline) control group. Aa= Amblygonocarpus andongensis

3.3.2. Effect of aqueous extract of stem all dose levels. At 400 mg/kg of the bark of Amblygonocarpus andongensis on extract, the inhibition of the charcoal gastrointestinal motility test in rats movement was comparable to that produced by atropine (0.1 mg/kg) the Administration of aqueous extract of stem reference drug while at 600 mg/kg of the bark of A. andongensis significantly extract the inhibition produced was greater (p<0.001) slowed down the propulsion of than the positive control (Figure 1). the charcoal meal towards the caecum at

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3.3.3. Effect of aqueous extract of stem mg/kg) was comparable with the reference bark of Amblygonocarpus andongensis on drug group (Table 2). PGE2-induced enteropooling assay in rats 3.4. Effect of aqueous extract of stem bark The administration of PGE2 resulted in of Amblygonocarpus andongensis on intestinal fluid accumulation in the rats. isolated guinea pig ileum experiment The extract at all dose levels significantly reduced the intestinal fluid volume when The extract of A. andongensis effectively compared with the control group. At the inhibited, in a dose related manner, the highest extract dose, aqueous extract of ACh-induced ileum contraction. The stem bark of A. andongensis produced the responses were comparable with that greatest reduction in volume of the obtained with atropine the reference drug intestinal fluid when compared with the (Figure 2). other groups including the reference drug group. The median extract dose group (400

Figure 1. Inhibitory effect of Amblygonocarpus andongensis on gastrointestinal motility. Data presented as mean%± SEM, n= 5 for all groups. *p<0.001 compared to the aqueous acacia suspension (AAS) control group.

Table 2: Effect of aqueous extract of stem bark of Amblygonocarpus andongensis on PGE2- induced enteropooling assay in rats

Groups Volume of intestinal fluid (ml) Inhibition of intestinal fluid (%) 200 mg/kg Aa 2.21 ± 0.13* 44.05 400 mg/kg Aa 1.35 ± 0.21** 65.82 600 mg/kg Aa 1.01 ± 0.11** 74.43 Loperamide 1.31 ± 0.12** 66.84 Control (vehicle) 3.95 ± 0.15 0 Aa= Amblygonocarpus andongensis. Data presented as mean ± S.E.M, n= 5 for all groups. *p<0.01, **p<0.001 compared with the vehicle control group.

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Figure 2. Antispasmodic effect of aqueous extract of stem bark of Amblygonocarpus andongensis on Acetylcholine- induced guinea-pig ileum contractions. *p<0.01, **p<0.001 compared with the control (100% dose response).

DISCUSSION Most agents with anti-diarrhoeal potential possess anti-secretory and anti-motility In the present study, the anti-diarrhoeal effects. In order to elucidate the possible properties of the stem bark of mechanism of anti-diarrhoeal potential of Amblygonocarpus andongensis, a plant our extract, castor oil was used to induce which is widely used for the treatment of diarrhoea in the rats. Castor oil is obtained diarrhoea in the North West Nigeria was from the seeds of a flowering plant Ricinus evaluated. The study was conducted communis (Euphorbiaceae). The active against castor oil-induced diarrhoea, component of castor oil is the ricinoleic gastrointestinal motility and PGE2 acid, which is liberated from the action of enteropooling models in Wistar rats. lipases on castor oil (Jia et al., 2008). The Isolated guinea-pig ileum experiment was liberated ricinoleic acid being poorly used to study the antispasmodic effect of absorbed causes local irritation and the plant in order to explore the possible inflammation of the intestinal mucosa, mode of anti-motility effect. leading to release of prostaglandins, which induces net secretion of water and Acute oral toxicity study was conducted to electrolytes into the small intestine and ascertain the safety of the plant extract on stimulate intestinal motility (Sarin et al., the rats. Oral administration of 3000 2013). These lead to hypersecretory mg/kg of aqueous extract of A. responses and diarrhoea (Kutchai, 2004; andongensis to the rats did not cause any Capasso et al., 1994). The secretory mortality or observable behavioural signs diarrhoea induced by castor oil is of toxicity thus suggesting that the oral associated with an activation of Cl- LD50 of A. andongensis in rats is greater channels, causing Cl- efflux from the cell. than 3000 mg/kg. According to Clarke and The efflux of Cl- results in considerable Clarke, (1977) substances with LD50 of secretion of water into the intestinal lumen 1000 mg/kg body weight are regarded as and immense watery diarrhoea. Thus, the safe or of low toxicity. This suggests that precise mechanism of action of castor oil the aqueous stem bark extract of A. is through elevated prostaglandin andongensis may be safe or of low biosynthesis (Ammon et al., 1974; Galvez toxicity. et al., 1993). Therefore, inhibitors of

Ugwah et al., Nig. Journ. Pharm. Sci., September, 2014, Vol. 13 No.2, P 01-11 prostaglandin biosynthesis were found to out the effect of drugs on peristaltic delay castor oil induce diarrhoea. movement. Atropine our reference drug is Loperamide, the reference drug, is a a parasympatholytic drug, which acts by piperidine butyramide derivative with µ- blocking the actions of acetylcholine at opioid receptor activity and generally muscarinic receptors. Atropine, as anti- produces rapid and sustained inhibition of diarrhoea, possesses anti-motility effect peristaltic reflex through depression of and acts by increasing the intestinal transit longitudinal and circular muscle activity time probably due to its anti-cholinergic (Sharkey and Wallace, 2011). This reduces effect (Brown and Taylor, 2000). In the the production of watery stool and same way as the atropine, the extract increases the onset of defecation. The drug significantly reduced the distance travelled also possesses anti-secretory and anti- by the marker in the intestine. The extract motility activities probably through at 600 mg/kg reduced intestinal propulsion intestinal opiate receptors (Craig and more than the reference drug. This proved Stitzel, 1990; Couper, 1987). In the present that the aqueous extract of A. andongensis study too, loperamide proved the claims by possess anti-motility effect, which in turn causing a delay in the onset of defecation permits the absorption of water and and a reduction in production of watery electrolyte thus, resulting in anti-diarrhoea stools when compared to the vehicle activity. This result obtained also suggests treated control rats. The extract effectively that A. andongensis may possess in inhibited both the onset of diarrhoea and addition to anti-motility and anti-secretory the number of diarrhoea faeces produced effects, some anticholinergic properties. similar to loperamide, the reference drug. This was further evaluated in an The significant dose-dependent reduction antispasmodic experiment using isolated in castor oil-induced diarrhoea in rats is a guinea-pig ileum. demonstration of the efficacy of Amblygonocarpus andongensis as an anti- As it is well known, cholinergic diarrhoea medicine. Hence, it can be stimulation often causes diarrhoea by assumed that the anti-diarrhoea action of increasing GI motility. Ach is a this plant was exerted by anti-secretory neurotransmitter from parasympathetic mechanism. nervous system. It acts on muscarinic and nicotinic cholinergic receptors. It is well In order to further elucidate the possible known that this neurotransmitter generates mechanism of anti-diarrhoeal activity of a contractile response in the ileum. aqueous extract of stem bark of A. Currently, Nitric oxide (NO) has been andongensis, it was necessary to verify its proposed to contribute to the inhibitory nor effects on GI motility. The gastrointestinal adrenergic, non-cholinergic tract (GIT) is innervated by the neurotransmitter that mediates GI motility sympathetic and parasympathetic fibers of in physiological and certain non- the autonomic nervous system. pathophysiological states, such as in Cholinergic stimulation often causes absorptive and secretory processes. NO diarrhoea by increasing GI motility. The could lead to gut secretion via elevation of effect of the extract on GI motility was cGMP and cAMP concentration (Liang et studied using activated charcoal meal as al., 2005). In order to study the mode of the marker. This is because activated anti-motility effect of the extract, the charcoal adsorbs drugs and chemicals on antispasmodic experiment was carried out the surface of the charcoal particles with ACh using guinea-pig ileum. thereby preventing absorption. Thus, GI Atropine, our reference drug, is a motility test with activated charcoal competitive antagonist for the muscarinic (charcoal meal test) is carried out to find ACh receptor (Pappano and Kutzung,

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2004). In this study, A. andongensis as antioxidant properties (Su et al., 2000) well as atropine sulphate inhibited ACh- which are supposed to be responsible for induced contractions of isolated guinea pig the inhibitory effects exerted upon several ileum in the same manner. This, as well as enzymes including those involved in the the GI motility experiment strongly arachidonic acid metabolism (Mora et al., suggests that the antispasmodic activity of 1990; Bimlesh et al., 2010). The A. andongensis may involve a cholinergic spasmolytic effects of flavonoids have mechanism. been shown to be nonspecific in activity as they inhibit both Ach- and BaCl2- induced In the PGE2-induced enteropooling contractions (Sarin et al., 2013). Terpenes experiment, A. andongensis reduced and terpenoids derivatives inhibit the diarrhoea by significantly inhibiting PGE2- release of autacoids and prostaglandins, induced intestinal fluid accumulation. It is thus inhibiting the secretion and motility also well documented that loperamide, our induced by castor oil and PGE2 (Yasmeen reference drug, reduces diarrhoea due to et al., 2010). Therefore, the tannins, prostaglandins and other irritants (Karim flavonoids and terpenes present in the and Adaikan, 1977). aqueous stem bark extract of A. andongensis are thought to be responsible The phytochemical analysis showed the for anti-diarrhoeal activity by increasing presence of tannins, flavonoids, saponins, colonic water and electrolyte reabsorption terpenes and glycosides which have been and inhibiting intestinal motility. It is thus reported to be responsible for anti- suggestive that the anti-diarrhoeal activity diarrhoea activities in some plants of aqueous stem bark extract of A. (Havagiray et al., 2004; Méité et al., 2009; andongensis may be due to the presence of Murugessan et al., 2000; Abdullahi et al., these phytochemical constituents. The 2001; Ojewole et al., 2009). Tannins results indicate that the aqueous extract of denature proteins by forming a complex A. andongensis possesses significant anti- (protein tannate) and this complex coats diarrhoeal activity due to its inhibitory the intestinal mucosa and makes it more effect both on gastrointestinal propulsion resistant while simultaneously diminishing and fluid secretion. The inhibitory effect of gastric secretions (Westendarp, 2006). the extract justified the use of the plant as They have been reported to possess a non-specific anti-diarrhoeal agent in various physiological properties such as traditional medicine. anti-secretory, anti-irritant, antimicrobial and antiparasitic (Venkatesan et al., 2005; CONCLUSION Mukherjee et al., 1998). The anti- diarrhoeal property of flavonoids has been The aqueous extract of the stem bark of attributed to their ability to inhibit Amblygonocarpus andongensis possesses intestinal motility and hydro-electrolytic anti-diarrhoeal properties which may be secretion (Di carlo et al., 1993; Rao et al., related to its anti-secretory and anti- 1997; Galvez et al., 1993), which are motility/antispasmodic activities. These known to be altered in diarrhoea. Various results validate its use in traditional studies have shown that flavonoids are medicine for the treatment of diarrhoea. able to inhibit the intestinal secretory More studies are however needed to isolate response, induced by PE2, inhibit and characterise the anti-diarrhoeal electrically-induced contractions and those components in this plant. that are induced by certain agonists, such as Ach, 5-hydroxyltryptamine (5-HT) and References histamine (Sanchez de Medina et al., 1997). In addition, flavonoids possess Abdullahi, A. L., Agho, M. O., Amo, S. S., Gamaniel, K. S., Wambebe, C., 2001.

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