Background: Fagara zanthoxyloides is a well known medicinal plant in Uganda. It is used extensively in malaria and other infections. However nothing is known about its toxicity. Objective: The objective of the study was to evaluate the acute toxicity of the methanolic extract of the root-bark of F. zanthoxyloides, in mice. Methods:  Methanolic extract of the root-bark of the plant was administered orally to mice at various dose levels to determine the acute toxic effects and the median lethal dose (LD50) in mice. Results: The LD50 of the methanolic extract was found to be 5.0 g/Kg body weight within 95 % confidence limits. The mice showed signs of cerebral irritation before dying. Histopathological examinations of the viscera showed congestion and focal necrosis of the liver and renal tubules. Conclusion: It was concluded that the extract of F. zanthoxyloides is safe, however the cerebral mechanism that lead to the death of the mice need to be investigated further

Anokbonggo, William W

Obua, Celestino

Ogwal-Okeng, Jasper W

PubMed

Jasper W. Ogwal-okeng

Celestino Obua

William W. Anokbonggo

CiteSeerX

Acute toxicity effects of the methanolic extract of Fagara zanthoxyloides (Lam.) root-bark

Background: Fagara zanthoxyloides is a well known medicinal plant in Uganda. It is used extensively in malaria and other infections. However nothing is known about its toxicity.

Objective: The objective of the study was to evaluate the acute toxicity of the methanolic extract of the root-bark of F. zanthoxyloides, in mice.

Methods:  Methanolic extract of the root-bark of the plant was administered orally to mice at various dose levels to determine the acute toxic effects and the median lethal dose (LD50) in mice.

Results: The LD50 of the methanolic extract was found to be5.0 g/Kg body weight within 95 % confidence limits. The mice showed signs of cerebral irritation before dying.  Histopathological examinations of the viscera showed congestion and focal necrosis of the liver and renal tubules.

Conclusion: It was concluded that the extract of F. zanthoxyloides is safe, however the cerebral mechanism that lead to the death of the mice need to be investigated further.
(African Health Sciences: 2003 3(3): 124-126

Ogwal-Okeng, Jasper W.

Anokbonggo, William W.

AJOL - African Journals Online

African Health Sciences Vol 3 No 3 December  2003 124Acute toxicity effects of the methanolic extract of Fagarazanthoxyloides (Lam.) root-barkJasper W. Ogwal-Okeng, Celestino Obua and William W.  Anokbonggo.Makerere University, Faculty of Medicine, Department of Pharmacology and Therapeutics,P. O. Box 7072, Kampala, UgandaABSTRACTBackground: Fagara zanthoxyloides is a well known medicinal plant in Uganda. It is used extensively in malaria and otherinfections. However nothing is known about its toxicity.Objective: The objective of the study was to evaluate the acute toxicity of the methanolic extract of the root-bark of F.zanthoxyloides, in mice.Methods:  Methanolic extract of the root-bark of the plant was administered orally to mice at various dose levels to determinethe acute toxic effects and the median lethal dose (LD50) in mice.Results: The LD50 of the methanolic extract was found to be 5.0 g/Kg body weight within 95 % confidence limits. The miceshowed signs of cerebral irritation before dying.  Histopathological examinations of the viscera showed congestion and focalnecrosis of the liver and renal tubules.Conclusion: It was concluded that the extract of F. zanthoxyloides is safe, however the cerebral mechanism that lead to the deathof the mice need to be investigated further.Keywords: Fagara zanthoxyloides, medicinal plant, toxicity, Uganda.African Health Sciences 2003; 3(3): 124 - 126BACKGROUNDFagara zanthoxyloides (Lam.) a Rutaceae, is widelydistributed in Uganda and other African countries.It is well known for its varied uses in traditionalmedicinal practices.  The root-bark extract is usedin treating elephantiasis, toothache, sexualimpotence, gonorrhoea, malaria, dysmenorrhoeaand abdominal pain1, 2, 3.  Workers in West Africahave reported the anti-sickling and antimicrobialactivity of the extracts of the plant4. In NigeriaF.zanthoxyloides is used as a chewing stick. Waterextracts from the plant showed activities againstbacteria significant to periodontal disease5, 6. Theanthelmintic activity of the methanolic extract ofthe root-bark of F.zanthoxyloides was also reported7, and it is a very popular anthelmintic amongst thevarious tribes in Uganda.  It has also been foundthat the alcoholic extracts of the root-bark possessesconsiderable antibacterial activity8. An anti-sicklingagent9, and an anti-inflammatory amide wereisolated from the plant10.As euphoria about the usefulness of medicinalplants grow, researchers have become aware of the toxicityof their extracts4. It is necessary to carry out toxicity studieson medicinal plants even though they have been used fordecades to determine acceptable from non-acceptabletoxicity levels. While F.zanthoxyloides has such diversetraditional medicinal use in Uganda and other Africancountries, there appears to be limited toxicity reports onit. The root extracts of the plant was shown to have somecytotoxic effects on the human erythroleukaemia cell line11.Compounds with cytotoxic activities have the potentialfor adverse effects to the human body. It is based on thispremise that its short-term safety was assayed using micein order to highlight any unrecognized toxic manifestations.OBJECTIVESThe general objective of this study was to determine thetoxicity level of the methanolic extract of the root-barkof F.zanthoxyloides in mice.Specific Objectivesa) To determine the acute toxicity value (LD50) of themethanolic extract of the root-bark of F.zanthoxyloidesin mice.b)  To determine histologically the acute toxicity effectsof F.zanthoxyloides on the internal organs of mice.MATERIALS AND METHODS Samples of F.zanthoxyloides, including the root, stem andaerial parts, were collected from Apac District, NorthernCorrespondence to:Celestino ObuaDepartment of Pharmacology and Therapeutics,Faculty of Medicine, Makerere University,P.O.BOX 7072, Kampala Uganda..Tel: 256(41) 532945 / 256 (77 )665919E-mail: cobua@med.mak.ac.ugAfrican Health Sciences Vol 3 No 3 December  2003 125Uganda, during the dry season.  It was identifiedby a taxonomist at the Natural ChemotherapeuticsResearch Laboratory, Kampala, and confirmedby the Department of Botany, MakerereUniversity.  A voucher specimen has beendeposited at the Department of Pharmacologyand Therapeutics herbarium, Makerere University.A total of 40 male albino mice, weighing 27 - 35g were used in the experiments.The methanolic extractPowdered root-bark of F.zanthoxyloides (100 g)was first extracted with ether at room temperatureto remove oil soluble components of the sample.This yielded 22.2 g (7.4%) of the crude etherealextract which was discarded. The marc was thensoaked in methanol. The extract was dried underreduced pressure giving a yield of 31.5 g (10.5%)of the crude methanolic extract, which was usedin the study. A stock solution was prepared fromthe alcohol extract by dissolving 2.0 g in 10 ml ofdistilled water.Toxicity TestsAn initial test was done to determine theapproximate lethal and non-lethal doses of theextract according to Turner [12].  Five groups ofeight mice each were used in the experiments. Theextract, in doses of 2.0, 3.0, 4.0, 6.0 and 10.0 g/Kg body weight respectively was administeredorally, using intragastric tubes, to the animals as asingle dose.  The control group was given an equalvolume of water.  The animals were observedfor 24 hours and the number of dead mice wasrecorded and used in the calculation of the acutetoxicity value (LD50).  The mice were alsoobserved for other signs of toxicity, such as,excitation, tremors, twitches, motor coordination,righting reflex and respiratory changes.  Apathologist carried out postmortem examinationsof the viscera (stomach, liver, heart, kidney andbrain) of the animals.RESULTSWithin six hours of administration of the extract,all the mice that received 10.0 g/Kg of the extracthad died. All the animals that received 2.0 g/Kgof the extract survived beyond the 24 hours ofobservation. The median acute toxicity value (LD50)of the methanolic extract of F. zanthoxyloidesdetermined to be 5.0 g/kg body weight within95 % confidence limits (3.45-7.25g/kg), Table 1.Table 1: Acute toxicity of the methanol extract ofF.zanthoxyloides in mice.Number of Doses of Number of PercentageMice  extract g/kg mice dead of mice dead8  0.0      0       08  2.0      0       08  3.0      2       258  4.0      3       378  6.0      5       628 10.0      8     100On administration of the extract, no immediatebehavioural changes were noted. The mice move and fednormally.  After twenty minutes, piloerection was noticedand the animals became restless, some trying to escapethrough the holes in the cages.  The animals did not vomit,neither was there ptosis.  The animals that received higherdoses went into convulsions and died in hyperextention.Post mortem examination did not reveal any grossabnormality of the brain, the organs of the chest andabdominal cavities.  Histopathological examination showedcongestion and focal necrosis in the liver and renal tubules13.DISCUSSIONAccording to Ghosh14, F.zanthoxyloides can be classified asslightly toxic, since the LD50 was found to lie between 0.5- 5.0 g/Kg.  The gram equivalent of the LD50 of theextract in an adult man would be 300g, that is, a plate fullof the extract, making it relatively safe.  It has beenobserved that overdose of F. zanthoxyloides extract is usuallynon-fatal; the victims tend to suffer self-limitinggastrointestinal disturbances2. Likewise, the extract wasadministered orally to the test animals. This way the sameroute used by the traditional healers in treating their patientswas used in the test animals. This would make any findingsin the mice easily translatable to what would be expectedin the human subjects. In any case the extract was not pureenough for parenteral route administration.The viscera of the animals did not show anymacroscopic changes that could point to the cause ofdeath.  However, since death occurred just afterconvulsions, it is postulated that the extract killed the miceby some action on the nervous system. Other workersfound active principles from the stem bark extract of theplant that appeared to exert their action on theneuromuscular transmission either by blockage of the post-junctional end-plate or by enhancing release ofneurotransmitters15. Similarly, the stem bark extract causedtonic-clonic seizures when injected intra-peritoneally tomice16.African Health Sciences Vol 3 No 3 December  2003 126 The histological changes that were dem-onstrated in the liver and kidney is however sig-nificant. However, because of genetic variation inresponse to drugs by different species, it is diffi-cult to directly translate the results of this study toother animal species or to man. This has been rec-ognized as a limitation in this study. Never the less,in view of the above findings, patients receivinglarger doses, or under-going prolonged medica-tion with the extracts of the plant, should haverenal as well hepatic functions evaluated regularly.These effects are indeed a warning regarding thepotential toxicity of the extracts of the plant.ConclusionsIt can be concluded the methanol extract ofF.zanthoxyloides is relatively safe within the normaldoses. However it is recommended that:a)  Further toxicity studies using different animalspecies is necessary.b) Sub-acute and chronic toxicity tests is plannedin order to determine the long-term effects of theextract.c) Further studies to elucidate the exact mechanismand loci of the fatal action of the extract need tobe carried out.AcknowledgementWe are grateful to the members of the Departmentof Pharmacology and Therapeutics, MakerereUniversity. We are further grateful to Mr. A.B.Kakooko of the Natural ChemotherapeuticsResearch Laboratory for identifying the plantspecimen, and to Dr. M. Odida of the Departmentof Pathology reported on the histopathologicalexamination of the tissues.References1. Ajanohoun J.E, Ahyi M.R.A, Ake-Assi L, et al.Traditional Pharmacopoeia : Contribution toEthnobotanical and Floristic Studies in Uganda.OAU/STRC. Lagos 1993.2. Anokbonggo, W.W., Odoi-Adome, R. and Oluju, P.M.Traditional methods of diarrhoeal management in Uganda.Bulletin of the World Health Organisation 1990;  68, 359-363.3. Watt J.M. and Breyer-Brandiwijk M.G. Medicinal andPoisonous Plants of Southern and Eastern Africa. 2ndEdition.  E and S Livingstone, London 1962.4. Sofowora E.A. Medicinal Plants and Traditional Medicine inAfrica, 1993; 159-176;179-189;195-238. Spectrum BooksLimited, Ibadan – Oweri – Kaduna – Lagos.5. Taiwo O., Xu H.X., and Lee S.F. Antibacterial activities ofextracts from Nigerian chewing sticks. Phytother. 1999; Res.13 (8): 675 – 9.6. Rotimi V.O., Laughon B.E., Bartlett J.G. et al Activities ofNaigerian chewing stick extracts against Bacteroides gingivalisand Bacteroides melaninogenicus. Antibacterial Agents andChemotherapy 1998;  32 (4): 598 – 600.7. Ogwal-Okeng, J.W.  The in vitro Study of the AnhelminticActivity of Crude Extracts of Two Ugandan Medicinal Plants:Cissus adenocaulis and Fagara zanthoxyloides. M.Sc. Thesis,Makerere University 19908. El-Said, F., Fadulu, S.O., Kuye, J.O. and Sofowora, A. NativeCures in Nigeria; Part II: The antimicrobial  properties of thebuffered extracts of chewing sticks. Lloydia 1971; 34, 172-175.9. Sofowora, E. A.,Isaac-Sodeye, W.A. and Ogunkoya, L.O.Isolation and characterisation of an anti-sickling agent fromFagara zanthoxyloides root. Lloydia 1975; 38, 169-171.10. Oriowo M.A.  Anti-inflammatory activity of piperonyl-4-acrylicisobutyl amide, an extractive from Zanthoxylumzanthoxyloides. Planta Medica 1982; 44 (1): 54-6.11. Comoe L., Kouamouo J., Jeannesson P. et al (1987). Cytotoxiceffects of the root extracts of Fagara zanthoxyloides Lam.(Rutaceae) on the human erythroleukaemia K 562 cell line.Ann. Pharm. 1987; 45 (1): 79-86.12. Turner,R.A. Screening Methods in Pharmacology. AcademicPress, London 1965.13. Odida M. Personal communication 1990.14. Ghosh, M.N.  Fundamentals of Experimental Pharmacology,2nd Edition. Scientific Book Agency, Culcutta, 1984; 154-157.15. Bowen J.M., Cole R.J., Bedell D. and Schabdach D. Neuro-muscular effects of toxins isolated from southern prickly ash(Zanthoxylum) bark. Am. J. Vet. Res. 1996; 57 (8): 1239-44.16. Navarrete A., and Hong E.  Anthelmintic properties of alpha-sanshool from Zanthoxylum liebmannianum. Planta Medica.1996; 62 (3): 250-1.

English

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2141606

Acute toxicity effects of the methanolic extract of Fagara zanthoxyloides (Lam.) root-bark

Abstract

Similar works

Full text

Available Versions

CiteSeerX

AJOL - African Journals Online