C Basic & Clinical Pharmacology & Toxicology 2006, 98, 135–141. Printed in Denmark . All rights reserved Copyright C ISSN 1742-7835 Hepatoprotection of D-Galactosamine-Induced Toxicity in Mice by Purified Fractions from Garcinia kola Seeds Oluwatosin A. Adaramoye 1 and Edward O. Adeyemi 2 1 Drug Metabolism and Toxicology Unit, Department of Biochemistry, University of Ibadan, Nigeria and 2 Department of Internal Medicine, Faculty of Medicine and Health Sciences, UAE University, Al Ain, United Arab Emirate (Received June 18, 2005; Accepted August 11, 2005) Abstract: The hepatoprotective effect of a biflavonoid complex, kolaviron, and its fractions from Garcinia kola seeds, together with the possible mechanisms involved was investigated in mice intoxicated with a single dose of D-galactosamine (GalNH 2 ). Likewise, the ability of vitamin E to attenuate the toxicity was examined. Kolaviron, was separated by thin- layer chromatographic technique into three fractions; Fraction I, Fraction II and Fraction III with RF values of 0.48, 0.71 and 0.76, respectively. Pretreatment with kolaviron, fraction I and fraction II at a dose of 100 mg/kg for seven consecutive days before challenge with a single dose of GalNH 2 (800 mg/ kg) significantly (P0.05) decreased serum alanine (ALT) and aspartate (AST) aminotransferases by 67%, 70%, 71% and 39%, 35%, 46%, respectively over GalNH 2 - only intoxicated mice. Vitamin E elicited respectively 65% and 39% reduction in the GalNH 2 -induced increase in the activities of these enzymes. In addition, pretreatment with kolaviron and fraction II significantly (P0.05) decreased the activity of microsomal g-glutamyl transferase (g-GT) by 42% and 46%, respectively. Administration of kolaviron to GalNH 2 -intoxicated mice also restored glucose-6-phosphatase to level that was comparable to the control (P0.05). These extracts except fraction III prevented the accumulation of serum and microsomal lipid peroxidation products, and also prevented the depletion of reduced glutathione (GSH) levels in the liver of GalNH 2 -intoxicated mice. Kolaviron, fraction I and fraction II at a dose of 100 mg/kg caused an induction of glutathione-S-transferase (GSH transferase) and uridyl glucuronosyl transferase (UDPGT) activities by 31%, 34%, 35% and 29%, 65%, 56%, respectively. GalNH 2 -induced toxic- ity was essentially prevented as indicated by a liver histopathologic study of liver slices from mice pretreated with kolaviron, fraction I and fraction II. This study shows that treatment with kolaviron, fraction I and fraction II (purified fractions from Garcinia kola) appeared to enhance the recovery from GalNH 2 -induced hepatotoxicity, and that the fractions I and II may therefore be responsible for the observed antihepatotoxic effect of kolaviron. This protection may be due to the ability of these extracts to induce the expression of phase II drug metabolizing enzymes. The liver is the main organ for metabolization of xenobiot- ics, and its capacity to carry out the several oxidative met- abolisms is associated with the high cellular content of cyto- chrome P450 (Coon et al. 1992). Liver toxicity due to poisons used in experimental model rarely occurs in human beings. It is, therefore, important to use hepatotoxic agents that are more relevant to human beings such as ethyl alco- hol and D-galactosamine (GalNH 2 ). Liver damage due to direct action of drugs is associated with GalNH 2 as the ad- ministration induces an inflammatory response in liver that resembles the reaction seen in viral hepatitis (Wojcicki et al. 1984). In fact GalNH 2 -induced hepatitis resembles viral hepatitis both biochemically and histologically (Wojcicki et al. 1984). GalNH 2 toxicity causes appearance of specific lesions in liver cells, one characterized by inhibition of nu- clear RNA and protein synthesis (Pickering et al. 1975). Since administration of uridine prevents and reverses in vivo inhibition of both syntheses, it is likely that acute deficiency of UTP due to accumulation of stable UDP- GalNH 2 is the intrinsic mechanism of its toxicity (Pickering et al. 1975). Author for correspondence: O. A. Adaramoye, Department of Bio- chemistry, University of Ibadan, Ibadan, Nigeria (fax 234 2 8103 043, e-mail aoadaramoye/yahoo.com). The protective effect of several natural products against GalNH 2 -toxicity has been demonstrated previously, for in- stance, Handa & Sharma (1990) confirmed the hepatopro- tective effect of andrographolide against GalNH 2 -toxicity in mice. Similarly, hepatoprotection by pollen extracts against GalNH 2 -intoxication in rats was reported by Wojcicki et al. (1984). Garcinia kola Heckel (family Guttiferae) is a herb grown in Nigeria. It has a characteristic astringent, bitter and resinous taste like raw coffee beans. The seed of this plant called ‘‘bitter kola’’ is highly valued in West Africa for its edibility and use in traditional hospitality. Extracts of vari- ous parts of the plant are used extensively in traditional African medicine (Ayensu 1978), especially for preparation of remedies for treatment of laryngitis, cough and liver dis- eases (Iwu 1985). Chemical investigations of seeds of Garci- nia kola have shown that they contain a complex mixture of phenolic compounds including GB-type biflavonoids, xanthones, triterpenes and benzophenones, as well as cyclo- artenol and its 24-methylene derivative (Cotterhill et al. 1978). The biflavanones are the most dominant in the Garci- nia species (Waterman & Hussain 1983). Kolaviron, the predominant constituent in Garcinia kola is a biflavonoid complex of the defatted alcoholic extract of the plant. This complex biflavonoid consists of C ª3/8øø – link