Effects of Theanine on Alcohol Metabolism and Hepatic Toxicity

Abstract

Theanine (Fig. 1), a major amino acid in green tea, is a umami (the fifth taste sensation)-component of tea and is contained 2-3% in tea leaves.1,2) Theanine is a glutamate derivative and is used extensively as supplements and beverages, because it has a brain nerve function such as a relaxing effect due to inducing alpha waves. [3][4][5][6] But there are few reports about pharmacological action of theanine in comparison with catechin or caffeine, major tea components, and its effects on living individuals have not revealed closely. In recent studies, we showed that theanine enhanced doxorubicin (DOX), an anthracycline derivative, induced antitumor activity, and confirmed that this action contributed to the increase in the concentration of DOX in tumor with inhibition of the efflux of DOX from tumor cells. [7][8][9][10][11][12][13] Besides, theanine induced the elevation of glutathione (GSH) level attributable to the increase of glutamate in the liver of mice, namely, theanine would reduce the adverse reaction of DOX. Although GSH in tissues are kept constant by homeostasis, whereas was decreased by disease or medicine or age.14) The usefulness of theanine was shown when the GSH level in liver decreased by the hepatic load of DOX. Furthermore, it was suggested that GSH level would increase by the metabolism of theanine. Thus, theanine was thought to be effective against tissue changes with GSH level reduction.On the other hand, it is suggested excessive uptake of alcohol causes a production of free radicals, a decrease of GSH level, and an increase in the amount of lipid peroxide (LPO) in liver, and shifting to an alcoholic liver injury. [15][16][17][18] In the liver, theanine is metabolized, converted glutamate, and induced to increase GSH level. 19) Namely, theanine may be expected to affect on to an alcoholic liver injury. Then, aiming at the prevention and medical treatment of a hepatic toxicity by the food components with little toxicity, we have studied the effect of theanine on ethanol metabolism and hepatic toxicity using ethanol single-administrated mice. To evaluate the effect of theanine on ethanol metabolism and its toxicity, theanine was intraperitoneally injected and ethanol was orally administered. MATERIALS AND METHODSMaterials Alcohol Dehydrogenase (ADH, EC 1.1.1.1) was purchased from Sigma Chemical Co. (St. Louis, MO, U.S.A.). The other chemicals used in this study were of the highest purity available.Animals Male CDF 1 mice (5 weeks of age and weighing 20-25 g) were obtained from Japan SLC Inc. (Hamamatsu, Japan). The animals were housed in a room maintained at 25Ϯ1°C and 55Ϯ5% relative humidity, and were given free access to regular chow pellets and water.Change of Ethanol Distribution in the Blood after Theanine Administration Subjects were assigned to one of three groups. One group was the ethanol alone group, which was administrated only 50% ethanol (3.0 g/kg, p.o.). The second group was the theanine pre-administrated group, which was administrated theanine (100 mg/kg, i.p.) before 1 h of ...

Effect of Dietary Epigallocatechin-3-gallate on Cytochrome P450 2E1-Dependent Alcoholic Liver Damage: Enhancement of Fatty Acid Oxidation

“…One possible mechanism by which EGCG prevents ethanol-induced hepatotoxicity is inhibition of the catalytic activity of CYP2E1, similarly to theanine (the predominant amino acid in green tea), 52) but JimenezLopez et al found that EGCG does not affect CYP2E1-mediated ethanol metabolism in the human hepatoma HepG2 cell line, which constitutively expresses human CYP2E1. 53) Similarly, we found in this study that dietary EGCG had no effect on CYP2E1 expression in ethanol-administered rats.…”

Inhibition property of green tea extract in relation to reserpine-induced ribosomal strips of rough endoplasmic reticulum (rER) of the rat kidney proximal tubule cells

“…ferent inducers in different organs (Hong et al, 2001;Das et al, 2002;Hiroyasu et al, 2002;Skrzydlewska et al, 2002;Zhang et al, 2002;Chen et al et al, 2004;Augustyniak et al, 2005;El-Beshbishy, 2005;Erba et al, 2005;Mohamadin et al, 2005;Sadzuka et al, 2005;Skrzydlewska et al, 2005;Yamamoto et al, 2006). Green tea suppresses reactive oxygen species (ROS) formation through polyhydroxy phenolics such as catechins that impart strong antioxidant activity.…”

Theanine is a candidate amino acid for pharmacological stabilization of mast cells

“…Recent studies have reported that theanine has various favorable physiological functions including neuroprotection in transient ischemic neuronal death (Kakuda et al 2000;Yamada et al 2005), relaxing effects under resting conditions (Abdou et al 2006;Lu et al 2004), hypolipidemic functions (Chiang et al 2005), regulation of systemic blood pressure (Yokogoshi et al 1995), suppression of the stimulatory action of caffeine (Nozawa et al 2000), modulation of neurotransmitter (Yamada et al 2009), and protection against hepatic toxicity (Sadzuka et al 2005). Additionally, studies on test rats have shown that repeated, extremely high doses of theanine cause little to no harmful psychological or physical effects (Borzelleca et al 2006).…”