Asian Journal of Medical Sciences 4(2): 75-78, 2012 ISSN: 2040-8773 © Maxwell Scientific Organization, 2012 Submitted: February 16, 2012 Accepted: March 16, 2012 Published: April 30, 2012 Corresponding Author: E. Umana Uduak, Department of Human Anatomy, Faculty of Medicine, Ahmadu Bello University Zaria- Nigeria. 75 Ulceroprotective Effect of Methanol Extract of Psidium guajava Leaves on Ethanol Induced Gastric Ulcer in Adult Wistar Rats E. Umana Uduak., J.A. Timbuak, S.A. Musa, D.T. Ikyembe, S. Abdurrashid and W.O. Hamman Department of Human Anatomy, Faculty of Medicine, Ahmadu Bello University Zaria-Nigeria Abstract: The present study investigates the anti-ulcer activity of methanol extract of P. guajava on ethanol induced gastric ulceration in adult Wistar rats. Twenty nine adult non pregnant female Wistar rats weighing between 160-225 gm were used for the study. Five rats were used for the acute oral toxicity test in accordance with the OECD guidelines 425. The remaining 24 rats were randomly divided in 4 groups of 6 rats each. Groups I and II which served as negative and positive controls orally received 2 mL/Kg body weight of distilled water and 50 mg/kg ranitidine respectively for a period of 10 days while groups III and IV were administered 500 and 1000 mg/kg of methanol extract of P. guajava leaves respectively also for 10 days. The next day, ulcer was induced by oral administration of 1 mL of 90% ethanol in all the groups after overnight fasting. The animals were sacrificed 1 h after induction of gastric ulceration and the stomachs were removed, processed and examined using a 6X hand held magnifying lens and mean ulcerative indices were scored accordingly. The result for the acute oral toxicity test showed no mortality nor was there any physical sign of toxicity. Significant dose dependent decrease in ulcer indices was observed among the P. guajava leaves extract treated groups as compared to the control groups. The study concludes that methanol extract of P. guajava is non toxic in acute doses and confers ulceroprotective activity on ethanol induced gastric ulcer in adult Wistar rats. Key words: Methanol extract, P. guajava leaves, ulceroprotective, wistar rats INTRODUCTION Guava (Psidium guajava) belongs to the family myrtaceae. It has spread widely throughout the tropics because it thrives in the variety of soil, propagated easily and bears fruit relatively quickly. The fruit contain numerous seed that mature into fruit within 4 years. It is an important food crop and medicinal plant in tropical and subtropical countries where it is widely use as food and in folk medicine. The fruit as well as its juice is freely consumed for its great taste and nutritional benefits. In many parts of Africa, the leaves, bark and roots of guava are used traditionally for the management, control and or treatment of an array of human disorder. Much of the traditional uses have been validated by scientific research (Kamath et al., 2008). The medicinal use of guava today is supported by numerous biomedical studies concerning the properties of the leave extract. Guava leaves are used as a quick remedy for the several gastrointestinal conditions; the leaf infusion is taken in Ghana, Senegal and Nigeria for stomach complaints such as constipation and dysentery (Jaiarj et al., 1999). Guava leaf is used traditionally in Africa folk medicine for several ailments including diabetes mellitus, diarrhoea, cough, painful menstruation and hypertension. It is also used to treat tooth decay, gum infection, sore throat to disinfect wounds and as an antiseptic (Geidam et al., 2007). A number of chemicals have been isolated from the plant including quercetin, guaijaverin, flavonoids and galactose-specific lecithins. Psidium guajava or guava is very rich in antioxidants and vitamins and also high in lutein, zeaxanthine and lycopene (Tee et al., 1997; Hobert and Tietze, 1998) and many of these have shown promising activity in many human trials (Abdelrahim et al., 2002). The extensive studies on the plant has shown active pharmacological activity of its major components and the results indicate potent anti-diarrheal, antihypertensive, hepatoprotective, antioxidant, antimicrobial, hypoglycaemic and antimutagenic activities (Nwinyi et al., 2008). The stomach is a site of massive production and concentration of Reactive Oxygen Species (ROS), far higher than other tissues or biological fluids (Graziani et al., 2005). The generation of these ROS plays a major role in the development of multiple pathologies, such as gastritis, peptic ulcerations or gastric adenocarcinoma (Oliveira et al., 2003). Peptic ulcers are sharp circumscribed lesions with loss of mucus membrane of mucosa of the stomach duodenum or any other part of the gastrointestinal tract expose to pepsin or acidic contents of the gastric juice (Anderson et al., 1994). It is brought about by the activity or imbalance between the mucosal