Hepatoprotective Effects of Arctium Lappa on Carbon Tetrachloride- and Acetaminophen-Induced Liver Damage

American Journal of Chinese Medicine, Spring, 2000 by Song-chow Lin, Tsao-chuen Chung, Chun-ching Lin, Tzuu-Huei Ueng, Yun-ho Lin, Shuw-yuan Lin, Li-ya Wang

Abstract: The root of Arctium lappa Linne (A. lappa) (Compositae), a perennial herb, has been cultivated for a long time as a popular vegetable. In order to investigate the hepatoprotective effects of A. lappa, male ICR mice were injected with carbon tetrachloride (C[Cl.sub.4], 32 [micro]l/kg, i.p.) or acetaminophen (600 mg/kg, i.p.). A. lappa suppressed the SGOT and SGPT elevations induced by C[Cl.sub.4] or acetaminophen in a dose-dependent manner and alleviated the severity of liver damage based on histopathological observations. In an attempt to elucidate the possible mechanism(s) of this hepatoprotective effect, glutathione (GSH), cytochrome P-450 (P-450) and malondialdehyde (MDA) contents were studied. A. lappa reversed the decrease in GSH and P-450 induced by C[Cl.sub.4] and acetaminophen. It was also found that A. lappa decreased the malondialdehyde (MDA) content in C[Cl.sub.4] or acetaminophen-intoxicated mice. From these results, it was suggested that A. lappa could protect the liver cells from C[Cl.sub.4] or acetaminophen-induced liver damages, perhaps by its antioxidative effect on hepatocytes, hence eliminating the deleterious effects of toxic metabolites from C[Cl.sub.4] or acetaminophen.

Arctium lappa Linne (A. lappa), a perennial herb, has been cultivated as a vegetable for a long time in Taiwan and Japan (Morita et al., 1993). Lin et al. (1996) reported that it has anti-inflammatory and free radical scavenging activities. Carbon tetrachloride (C[Cl.sub.4]) induced liver damage is the best characterized animal model of xenobiotic-induced free radical-mediated hepatotoxicity (Recknagel, 1989). It is metabolized by microsomal cytochrome P-450 to the reactive trichloromethyl radical (.C[Cl.sub.3]), which may damage hepatocytes by covalently binding to polyunsaturated fatty acid (PUFA) on cellular membrane during lipid peroxidation (Comporti, 1985; Slater, 1985). Acetaminophen (paracetamol) is normally a very safe drug, but it may produce acute centrilobular hepatic necrosis, when given at high doses in humans and experimental animals (Rumore and Blaiklock, 1992; Prescott, 1983). Acetaminophen damages the liver through the formation of a highly reactive metabolite formed by P-450 (Dahlin et al., 1984; Potter et al., 1989), which is trapped and inactivated by preferential conjugation with hepatic glutathione. When acetaminophen was given in hepatotoxic dose, glutathione is depleted and the toxic metabolite binds covalently to vital proteins and enzymes, causing hepatocellular damage and necrosis (Albano et al., 1985). In this study, the hepatoprotective effects and action mechanisms of A. lappa on C[Cl.sub.4] and acetaminophen-induced liver injury were investigated.

Materials and Methods

Animals and Treatments

Male ICR mice, weighing 22-28 gm, were purchased from the Animal Center of National Taiwan University and kept on the commercial diet (Fu-so Co., Ltd., Taiwan) and tap water ad libitum.

Induction of Hepatotoxicity

C[Cl.sub.4] was dissolved in corn oil and administered i.p. to mice at a dosage of 32 [micro]l/kg. The control mice received only corn oil in a similar manner. Acetaminophen was dissolved in 0.9% normal saline with polyethylene glycol 400 as a solubilizer (1:1, v/v), then administered i.p. to mice at a concentration of 600 mg/kg, while the control group received saline only. Untreated mice served as the blank group. Animals were sacrificed at 24 hrs after i.p. injection of hepatotoxins. Blood was collected by cardiac puncture and livers were removed immediately, homogenized in 4 volumes of 1.15% KCl solution. The homogenate was centrifuged at 9,000 g for 20 min to sediment the nuclear and mitochondrial fractions. The supernatant fraction was centrifuged at 100,000 g for 60 min. The microsomal pellets obtained were suspended in 0.1 M potassium phosphate buffer (pH 7.4) and stored at -70 [degrees] C until microsomal enzyme assay was conducted.

Preparation of Crude Drugs

The root of Arctium lappa L. was collected from local markets and authenticated by C.C. Lin, Kaoshiung Medical College.

100 gm of roots of Arctium lappa were ground to fragments and boiled with 1 liter of distilled water in a Chinese herbal decocter for 1 hr. The extract was filtered and the residue was boiled and filtered again. The filtrates were combined and lyophilized. When orally administered to mice, the crude drug powder was dissolved in normal saline at a concentration of 300 mg/10 ml/kg body weight.

Biochemical Assays

Animals were lightly anesthetized with ethyl ether 24 hrs after the administration of hepatotoxins. Blood samples were allowed to coagulate at room temperature for 1 hr, serum was then separated by centrifugation at 4 [degrees] C, 5,000 rpm for 10 min. Serum concentrations of GOT and GPT were measured using a CH-100 autoanalyzer (Texas International Laboratory, USA) and Sigma GOT and GPT optimized reagents (Sigma Chemical Company, P.O. Box 14508, St. Louis, MO 63178, USA) according to the method of Bergmeyer et al. (1978). The livers were removed immediately after blood collection, and microsomes were prepared.