Antiulcer effect of the ethanol extract of Kigelia africana.Lam, Benth (Bignoniaceae)

Read printer friendly
 Subscribe in a reader

Share with others

 

Omonkhelin J Owolabi M.sc Pharmacology and Toxicology
Department of Pharmacology and Toxicology
Faculty of Pharmacy
University of Benin

Address:
Nigeria

Zuleikha A.M. Nworgu PhD Pharmacology and Toxicology
Department of Pharmacology and Toxicology
Faculty of Pharmacy
University of Benin

Address:
Nigeria

Citation: O. Owolabi & Z. Nworgu : Antiulcer effect of the ethanol extract of Kigelia africana.Lam, Benth (Bignoniaceae). The Internet Journal of Pharmacology. 2009 Volume 7 Number 1

Abstract

The anti-ulcer activity of the ethanol extract of Kigelia africana was evaluated in Wistar albino rats. This was done to verify its ethno medicinal use in the treatment of ulcer. Ulcer was induced by administering 1 ml of absolute ethanol orally to rats an hour after the administration of drug and extract. Group 1 (normal saline 10 ml/kg), groups 2, 3 and 4 (250, 500 and 1000 mg/kg respectively) while group 5 ranitidine (100 mg/kg). The effect of the extract (1000 mg/kg) after induction of ulcer with ethanol (curative effect) was also investigated. A second model involved the oral administration of indomethacin (20 mg/kg) to rats, an hour after the administration of drug and extract. The first three groups received the ethanol extract (100, 200 and 400 mg/kg), the fourth, ranitidine (100 mg/kg) and the control, 10 ml/kg of normal saline. In another set of experiment (curative study), the effect of the extract (400mg/kg) administered after induction of ulcer with indomethacin (20mg/kg) was investigated.Kigelia africana at oral doses of 100, 200 and 400 mg/kg caused a marked inhibition of the ulcerations induced by indomethacin (p<.01, p<.0001 p<.0001) respectively. The extract in the curative study, produced complete protection against ulcerations. However in the ethanol induced ulcers, only the 500 and 1000 mg/kg caused a marked inhibition of the ulcerations (p<.01), in both the preventive and curative study. The results points to the fact that the crude extract possesses gastro cytoprotective properties.

Introduction

The origin of medicinal plants and their uses dates back to ancient times. The use of plants for medicinal purpose is almost universal among non-industrialized societies ¹ . World Health Organization described a medicinal plant as one in which some parts can be used directly in the management of a disease. The different parts of the plant used include the stem bark, leaves, root, shoot and flowers ² .

The plant Kigelia africana also called Kigelia pinnata is a tropical African genus of large trees and shrubs. The sausage tree as popularly known is widespread in Nigeria and is well distributed in the eastern, mid-west and western parts of Nigeria ³ . Traditional uses of K. africana include the use of the stem bark for the treatment of malaria, rheumatism, wounds, ulcers, retained placenta, venereal diseases, diarrhoea and to combat infections ³ .

An ulcer is any break in the skin or in a mucous membrane. The mucous membrane can be described as a thin tissue that lies the interior surface of body openings. Ulcer is used most commonly to refer to ulcers that occur in the upper part of the digestive system, such as peptic ulcers ⁴ .

In previous studies carried out on the plant, the analgesic and anti-inflammatory activities of the stem bark ⁵ , antibacterial activity of the stem bark ⁶ , antibacterial activity of the fruits ⁷ , central nervous stimulant effect of the stem bark ⁸ , smooth muscle relaxant activity of the stem bark ⁹ and verification of its antipyretic properties ¹⁰ were done.

In traditional medicine, many plants are claimed to have an antiulcer effect without

any scientific basis. In this study, the biological activity of the ethanol extract of the plant material was evaluated for its effect on ethanol and indomethacin induced ulcers to examine the claims made of its effects in ulcer therapy in folk medicine.

Materials and Methods

Drugs and Chemicals:

Absolute ethanol (Sigma Aldrich); Indomethacin (Sigma Aldrich ); Sodium Carbonate (BDH Chemicals, England ); Ranitidine (Dexon company, Isreal) and Formaldehyde (Merck, Germany).

Collection and Identification of Plant Material:

The barks of Kigelia africana were collected in Okhoro Village, Egor Local Government Area of Edo State, Nigeria, between February and July 2005. The botanical identity of the plant and its bark were authenticated by Alhaji Alasa Abubakar (of blessed memory), a hebarium curator of the Department of Pharmacognosy, Faculty of Pharmacy, University of Benin, Nigeria. Botanical authentication was confirmed at the Forestry Research Institute of Nigeria (FRIN), Ibadan, Nigeria where a voucher specimen (No. FHI107654) was deposited for future reference.

Extraction and Preparation of the Extract:

Immediately after collection, barks were cut into small pieces and air dried. The dried barks were pulverized into a smooth powder using impact mill (Makers: Christy and Morris Ltd. Process Engineers, Chelmsford. England. Model 474/54),weighed and kept for further analysis. Extraction was done by macerating 400g of the sample in absolute alcohol (2.5 litres) and left for 72hours. The resultant mixture was filtered and the filtrate concentrated with the aid of a vacuum pump and rotavapour at 40 ° C, giving a yield of 3.78%.

The concentrated extract was stored in air tight containers, labelled and refrigerated at -4° C prior to use.

Animals:

Albino wistar rats weighing between 100-150 g of either sex were obtained from the Animal house, Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Benin. The animals were maintained on a standard diet (Ewu feeds, Edo State, Nigeria) and had access to food and water ad libitum. All animals were acclimatized for two weeks and fasted from food, 24 hours prior to the experiment and water withdrawn 2 hours before the commencement of the experiments.

Animals were exposed to natural lighting conditions and were handled according to standard experimental protocols approved by the Faculty of Pharmacy, Animal Ethics Committee, University of Benin.

Pharmacological screening:

Ethanol induced ulcer:

The rats were randomly divided into 5 groups of 5 animals each and starved for 24 hours but had free access to water. Water was however withdrawn 2 hours before experiments. Group 1 served as control and received normal saline, Groups 2, 3 and 4 received 250, 500 and 1000 mg/kg of the extract respectively by oral intubations, while group 5 received 100 mg/kg ranitidine orally ¹¹ .

One hour later, 1 ml of absolute ethanol was administered orally to all the groups. An hour following ethanol administration, the animals were sacrificed under anaesthesia. The stomach was isolated, opened along the greater curvature and washed.

The effect of the extract (1000 mg/kg) administered orally 15 mins after induction of ulcer with ethanol (curative effect) was also investigated according to the procedure already described above.

Macroscopic examination of the stomachs of the animals in all the groups was done. The presence of ulcers was counted using a magnifying glass. The diameter of the ulcers was measured using a vernier caliper and scored on scale of 0-10 ¹² .

The ulcer index (UI) was calculated thus:

UI = U_N + U_S + U_P X 10 ^-1.

Where U_N = Average number of ulcer per animal

U_S = Average of severity score

U_P = Percentage of animals with ulcers.

Indomethacin induced ulcer:

Rats were randomly allotted to 5 groups of 5 animals each and starved for 24 hours with access to water ad libitum. Water was however withdrawn 2 hours prior to the experiment. Group 1 served as the control and received normal saline (10 ml/kg) orally. Group 2, 3, and 4 were administered by oral intubations the extract at doses of 100, 200 and 400mg/kg respectively. Group 5 received ranitidine (100mg/kg orally). This was done one hour before oral administration of indomethacin 20 mg/kg in 2 % sodium carbonate solution ^11,13 .

Six hours later, each rat was sacrificed under anesthesia and the stomach removed. 2 ml of formol saline was injected into the totally ligated stomach for overnight storage. The next day, the stomach was opened along the greater curvature and washed.

In another set of experiment (curative study), the effect of the extract (400 mg/kg) administered orally 2 hours after induction of ulcer with indomethacin (20 mg/kg) was investigated. The procedure used is as already described above.

Macroscopic examination of the stomachs of the animals in the groups was done. The presence of ulcer was noted and scoring done according to the method of ¹² .

Buffer capacity of the ethanol extract of Kigelia africana

The buffer capacity of the extract was evaluated as the ability to resist PH change upon the addition of 1 and 2ml, 0.1N HCL or 0.1 N NaOH ¹⁴ .

Statistical analysis

All data were expressed as mean ±SEM. Where applicable, the data were analysed statistically by Student’s t-test using Graph pad instant version 2.05a. The level of significance was P < 0.05. n represents five per group.

Results

Intense and widespread thickened gastric lesions of the mucosa were evident in control rats that received 1 ml of absolute ethanol. Pre-treatment with Kigelia africana (500 and 1000 mg/kg) caused a significant dose related reductions in both number and severity of the gastric lesions, (P<0.01) reductions in the ulcer index in both the preventive and curative studies, and these effects were also found to be better than the effect of ranitidine (table 1).

Table 2 shows the effect of the extract on indomethacin induced ulcers. The control group had an ulcer index of 12.78. Pretreatment with the extract produced a dose dependent reduction in both the number and severity of ulcers. This was 11.20, 5.55 and 5.10 for the 100, 200 and 400 mg/kg doses respectively. While for ranitidine it was 5.13.

All the doses levels of the extract and ranitidine caused a significant (p<0.01, p<0.0001 and p<0.0001) for 100, 200 and 400 mg/kg doses respectively reduction in the ulcer index.

The extract administered 2 hours after indomethacin administration in the curative study, produced complete protection against ulcerations. No ulcers was noted, which makes the extract significantly (p<0.0001) better than ranitidine.

The extract did not show buffer capacity (Table 3). The addition of 1 and 2 ml 0.1 N HCL and 0.1 N NaOH produced a PH variation in 1 ml of the extract (equivalent to 100 mg of the extract)

Table 1 : Antiulcer activity of the ethanol extract of the stem bark of K. africana, normal saline and ranitidine on ethanol-induced ulcer in rats

Values are expressed as mean ulcer index ± SEM, (n=5 rats per group). ^a P<0.01, significantly different from the control.

K.A : ethanolic extract of Kigelia africana

Table 2 : Antiulcer activity of the ethanol extract of the stem bark of K. africana, normal saline and ranitidine on indomethacine-induced ulcer in rats

Values are expressed as mean ulcer index ± SEM, (n = 5 rats per group). ^a P<0.01 and ^b P<0.0001, significantly different from the control group.

K.A : ethanolic extract of Kigelia africana

Table 3 : Buffer capacity of the ethanol extract of the stem bark of K. africana. 1 ml extract is equivalent to 100 mg/ml

Discussion

The anti-ulcer property of the ethanolic extract of Kigelia africana was evaluated against gastric lesions induced by indomethacin and ethanol. Although the etiology of ulcer in most cases is unknown, it is generally accepted that they result from an imbalance between aggressive factors and the maintenance of mucosal integrity through the endogenous defensive mechanisms ¹⁵ . To regain the balance, there are different therapeutic agents including medicinal plant extracts that are used to inhibit gastric acid secretion. Kigelia africana extract is one of such medicinal drugs used in the present study primarily to evaluate the antiulcerogenic or ulcer preventive potency.

The results show a dose dependent gastro-protective effect in the two models of ulcer.

In the indomethacin model of ulceration, the extract showed better significant protection (P<0.0001) at all doses tested, when compared to the ethanol-induced model (P<0.01).

The extract (400 mg/kg) curative, administered, after the ulcerogen produced complete protection against ulceration which made the extract significantly better than ranitidine.

Prostaglandins are known to protect gastric mucosal cells against injury caused by indomethacin ^16,17 thus it is possible that the extract stimulates the production of endogenous prostaglandins, which gives protection.

In the ethanol-induced ulceration, the highest dose (1000mg/kg) showed significant protection (P<0.01), better than that of ranitidine.

The reduction in ulcer index in both models (preventive and curative) shows the ability of the extract to protect the gastric mucosal against ulceration as well as suppression of already established ulcers.

The extract did not show buffering capacity and so may neither be acting by neutralization of stomach acidity, like antacids nor dilution of the ulcerogen in the gastro-intestinal tract.

Conclusion

The results suggest that the ethanolic extract of Kigelia africana has a potential antiulcer effect.

Its mechanism might be via release of prostaglandins and possibly free radical scavengers which protect the gastric mucosa.

Acknowledgements

We wish to express our profound gratitude to Mr. Dickson Uwaya the Department of Science Laboratory Technology for his dedication and technical assistance.

References

1. Oliver, B (1990). Medicinal plants of Nigeria. Nigeria college of Arts, Science and Technology. Lagos. Pp:138. (s)

2. WHO (1977). Resolution, promotion and development of training and research in traditional medicine. WHO DOCUMENT. 30:49 (s)

3. Burkill, HM (1985). The useful plants of West Tropical Africa. Planta. WT Afr. 1:254-257. (s)

4. Grant, WT (1996). The ulcer story: The Authoritative Guide to Ulcers, Dyspepsia and Heartburn. New York. Plenum press. (s)

5. Owolabi, OJ., Omogbai, EKI (2007)a. Analgesic and anti-inflammatory activities of the ethanolic stem bark extract of Kigelia africana (Bignoniaceae). African Journal of Biotech. 6 (5) :582-585. (s)

6 Owolabi, OJ. , Omogbai, EKI.,Obasuyi, O (2007)b. Antifungal and antibacterial activities of the ethanolic and aqueous extract of Kigelia africana (Bignoniaceae) stem bark. African Journal of Biotech. 6 (14):1677-1680. (s)

7. Grace, OM., Light, ME., Lindsey, KL., Moholland, DA., Staden, JV., Jager, AK (2002). Antibacterial activity and isolation of antibacterial compounds from the fruit of the traditional African medicinal plant Kigelia africana. South African Journal of Botany. 68: 220-222. (s)

8. Owolabi, OJ., Amaechina, FC., Eledan, AB (2007). Central nervous stimulant effect of the ethanolic stem bark extract of Kigelia africana (Bignoniaceae). Journal of medicinal plant research. 2 (2): 020-23. (s)

9. Owolabi, OJ., Omogbai, EKI., Eledan, AB., Falodun, A (2008). Smooth muscle relaxant activity and proximate evaluation of Kigelia africana . Canadian journal of pure and Applied science. 2(2): 405-401. (s)

10. Owolabi, OJ., Omogbai, EKI (2007)b. Verification of the folkloric antipyretic claim of the aqueous and ethanolic extract of Kigelia africana. Journal of Pharmacy and Bioresources. 4(1): 1-5. (s)

11. Robert, A (1979). Cytoprotection by prostaglandins. Gastroenterol. 77: 761-767 (s)

12. Martin, MJ (1988). Antiulcerogenicity of the flavonoidbfraction from Diltrichia viscose (L) in rats. Phyto. Res. 2 (4): 183-186. (s)

13. Franzone, JS., Cirillo, RC (1988). Cytoprotective activity of deboxaient: a possible interference with PG and prostacyclin metabolism in rat gastric mucosa. Int. J. Tiss. Reac. 10: 149-158. (s)

14. Trucheau, M., Gazave, JM., Page, M (1975). Etude d’une ptoduit ambivalent normalisant le pH gastrique. Application de la methode telemetrique (Capsule de Heidelberg). Annales Pharmaceutique Francaise. 33: 313-319 (s)

15. Gisbert, JP., Blanco, M., Mateos, JM (1999). Helicobacter pylori negative duodenal ulcer prevalence and causes. Medline. 44 (11): 2295-22302. (s)

16. Roberts, A (1976). Antisecretory, antiulcer, cytoprotective and diarrhogenic properties of prostaglandins. Advances in prostaglandins and Thromboxane Research. 2: 507-520. (s)

17. Whittle, BJR (1977). Review: Mechanism underlying gastric mucosal damage induced by indomethacin and bile salts and the action of prostaglandins. Br. J. Pharmacol. 60: 455-460 (s)

This article was last modified on Sat, 18 Jul 09 10:19:10 -0500

This page was generated on Fri, 19 Mar 10 23:48:51 -0500, and may be cached.