Afework, Mekbebk (PhD)Ayele, Mengistu2018-06-122023-11-292018-06-122023-11-292015-08http://etd.aau.edu.et/handle/123456789/459Human beings use plants for the purpose of disease control and prevention. Maytenus gracilipes celastraciae is a plant having vital traditional medicinal values for treating several human ailments such as for headache, epilepsy, allergic, peptic ulcer, cancer and immflamations. The present study was carried out to evaluate the acute and subchronic toxic effects of aqueous leaves extracts of maytenus gracilipes celastraciae (kombolcha) on some blood parameters and histopathology of liver and kidney in mice. LD50 was determined. The thesis was carried out in Addis Abeba University, College of Health Science, School of Medicine, Department of Anatomy (Histology Laboratory).The study was conducted from May, 2014 -July, 2015.The aqueous leaves extracts of M.gracilipes were employed in swiss albino mice in single oral dose for acute study and repeated oral dose for subchronic study. The LD50, of aqueous extracts of Maytenus gracilipes was found to be 10,000 mg/kg body weight. In the Subchronic study, the extract was administered orally at doses of 700 and 2100 mg/kg/day for 90 days . Body weight, biochemical and hematological parameters were determined at the end of the 90 days of daily extract administration. In sub chronic toxicity study daily oral administration of aqueous extract at 700 and 2100 mg/kg body weight/day did not result in death or significant changes in body weight, hematological and biochemical parameters. Studies on Histopathological examination of selected organs (liver and kidney) showed normal architecture suggesting absence of morphological disturbances. However, at 700 mg/kg body weight liver showed pyknotic nuclei and at 2100mg/kg some cellular infiltrates near the central vein and portal region, where as, in kidney peritubular infiltration and focal mono nuclear leukocytic infiltration was observed at higher dose. Key words: Maytenus gracilipes, Aqueous extract, acute toxicity, subchronic toxicity, Histopathological studies.en-USMaytenus Gracilipes; Aqueous Extract; Acute Toxicity; Subchronic Toxicity; Histopathological studiesThesis