Pak. J. Pharm. Sci., Vol.23, No.2, April 2010, pp.160-169 160 SUBCHRONIC TOXICITY STUDIES OF THE ETHANOLIC ROOT EXTRACT OF CROTON ZAMBESICUS JUDE E OKOKON, PAUL A NWAFOR AND MEMFIN D EKPO* Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Uyo, Uyo, Nigeria *Department of Chemical Pathology, College of Health Sciences, University of Uyo Teaching Hospital, Uyo ABSTRACT Subchronic toxicity study of the crude root extract of Croton zambesicus (27-81mg/kg), which is used traditionally as malarial remedy, was carried out in rodents to evaluate the safety profile. Effect of the extract on body weights, haematological indices as well as liver and kidney functions and histology of various organs were investigated. Subchronic treatment of rats for 21 days caused comparable increase in body weights of rats in extract treated and control groups. The extract caused a dose-dependent increases in RBC, PCV, Hb, WBC, bleeding time and clotting time. The increases were only significant (P<0.05) at the highest dose of the extract (81mg/kg) for RBC and WBC when compared to control. There was no significant (P>0.05) differences in the means of other haematological parameters in the extract treated groups compared to control. The extract caused significant (P<0.05-0.01) increases in the level of serum total protein, ALT, ALP, total bilirubin and total cholesterol. The was no significant (P>0.05) changes in the levels of albumin and AST. The extract did not produce any significant (P>0.05) changes in the mean concentrations of urea, creatinine, Na+, K+, and Cl- ions of rats in the extract treated groups compared to that of control. Histopathologic analysis of the vital organs revealed no significant lesions in the brain, liver, kidney, heart, spleen, ovary, and testis. The results suggest the extract to be safe when taken orally though with an insignificant effect on the liver. Keywords: Croton zambesicus, subchronic, toxicology, haematology, liver, kidney. INTRODUCTION Croton zambesicus Muell Arg. (Euphorbiaceace) (syn C. amabilis Muell. Arg. C. gratissimus Burch) is an ornamental tree grown in villages and towns in Nigeria. It is a Guineo – Congolese species widely spread in tropical Africa. Ethnobotanically, the leaf decoction is used in Benin as anti hypertensive and anti- microbial (urinary infections) (Adjanohoun et al, 1989) and in parts of Nigeria as antidiabetic and malarial remedy (Okokon et al., 2005a, 2006). The roots are used as antimalarial, febrifuge and antidiabetic by the Ibibios of Niger Delta region of Nigeria (Okokon and Nwafor, 2009a). The root is also used in Sudan for menstrual pain (El-Hamidi, 1970) and as aperients (Ngadjui et al., 1999). Boyom et al. (2002) studied the composition of essential oils from the leaves, stem and roots of Croton zambesicus and found the three types of oils to be similar in composition, with those from the leaves and stem rich in monoterpenes, while that of the root bark contains sesquiterpenes. The root and stem bark oils were found to be rich in oxygen- containing compounds, with spathulenol and linalool as major components. Okokon and Nwafor (2009a) reported that the root extract whose LD50 is 273.86 mg/kg contains alkaloids, saponins, terpenes, tannins, phlobatannins, anthraquinones and cardiac glycosides, while flavonoids were reported to be absent. Block et al. (2002) isolated entrachyloban-3β-ol, an ent-trachylobane diterpene from dichloromethane extract of the leaves and reported that the diterpene has a cytotoxic activity on HeLa cells. Also two new trachylobane – and one isopimarane type diterpenoids; ent-18-hydroxy-trachy- loban-3-one, ent-trachyloban-3- one, isopimara-7,15-dien- 3β-ol, together with transphytol, β-sitosterol, α-amyrin and stigmaterol have been isolated from the leaves (Block et al., 2004). Crotonadiol, a labdane diterpenoid, clerodane, crotocorylifuran and two trachylobanes; 7β- acetoxytrachyloban – 18 – oic acid, trachyloban - 7β, 18 – diol, lupeol, β-sitosterol and its 3-β-glucopyranosyl derivative were isolated from the stem bark (Ngadjui et al, 1999). Ngadjui et al., (2002) further isolated three clerodane diterpenoids, crotozambefurans A, B and C from the stem bark. Studies have reported on the antimicrobial properties of the leaf and stem (Abo et al, 1999). The ethanolic leaf extract has been reported to possess antiplasmodial (Okokon et al., 2005a), antidiabetic (Okokon et al., 2006), anti-inflammatory, analgesic and antipyretic activities (Okokon et al., 2005b), while the root extract has been reported to possess antimalarial (Okokon and Nwafor, 2009a) and anticonvulsant and antiulcer activities (Okokon and Nwafor, 2009b). Information on biological activity of the root are scarce. We therefore investigated the antiiflammatory, analgesic and antipyretic activities of the root extract of the plant to ascertain the folkloric claim of its medicinal properties in Corresponding author: e-mail: judeefiom@yahoo.com