Biol. Pharm. Bull. 28(11) 2155—2157 (2005)

sources, it is important that relevant models of human liver toxicosis are used in order to identify agents with therapeutic potential. Thus, we considered the use of hepatotoxic agents relevant to human liver toxicosis in assay protocols. Examples of such hepatotoxic agents include pharmaceutical agents like tacrine and nitrofurantoin. Tacrine (1,2,3,4tetrahydro-9-aminoacridine hydrochloride) is an acetylcholinesterase inhibitor that is approved for the treatment of Alzheimer’s disease. However, tacrine treatment for Alzheimer’s disease results in reversible hepatotoxicity in 30—50% of patients, which seriously limits its clinical use. Nitrofurantoin {1-(5-nitro-2-furfurylideneamino)-hydantoin} is a synthetic nitrofuran that is commonly used for the treatment and prophylaxis of urinary tract infections, but its use is associated with liver cirrhosis and fatal liver necrosis. Therefore, the identification of constituents in natural products that have preventive effects on tacrineor nitrofurantoininduced hepatotoxicity would be valuable. In the present study, an immortalized human hepatoma cell line, Hep G2 was employed to screen for agents that protect against tacrineor nitrofurantoin-induced hepatotoxicity. This cellline was chosen because it retains many cellular functions often lost by primary hepatocytes, e.g., the expression of hepatocyte-specific cell surface receptors and the synthesis and secretion of plasma proteins. During the course of our continuing screening studies for natural hepatoprotective agents, we found that the EtOAc soluble fraction of the MeOH extract of Galla Rhois, a traditional Chinese medicine to treat diarrhea and bleeding, showed promising hepatoprotective activity. We describe the isolation and identification of the hepatoprotective constituents of Galla Rhois.