Suppression of inducible nitric oxide synthase expression and amelioration of lipopolysaccharide-induced liver injury by polyphenolic compounds in Eucalyptus globulus leaf extract |
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Authors: | Keiichiro Sugimoto Sayaka Sakamoto Kazuya Nakagawa Shuichi Hayashi Naoki Harada Ryoichi Yamaji Yoshihisa Nakano Hiroshi Inui |
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Affiliation: | 1. Department of Applied Biological Chemistry, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan;2. Research and Development Center, Nagaoka Perfumery Co. Ltd., Ibaraki, Osaka 567-0005, Japan;3. Osaka Women’s Junior College, Fujiidera, Osaka 583-8558, Japan |
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Abstract: | Eucalyptus leaf extract (ELE) is rich in hydrolyzable tannins. We examined the effects of ELE and its constituents on lipopolysaccharide (LPS)-induced liver injury in mice. Mice fed a diet supplemented with 1% ELE were intraperitoneally administered LPS. Six hours later, the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly lower in the ELE-supplemented mice than in the controls; LPS-induced hepatic inducible nitric oxide synthase (iNOS) expression was also suppressed. ELE lowered LPS-stimulated iNOS expression in cultured RAW 264.7 macrophages. Furthermore, the aglycones of hydrolyzable tannins, gallic acid (GA) and ellagic acid (EA), inhibited iNOS induction to a greater extent than did ELE (15-fold higher). When mice were fed a 1% GA or EA diet, the increase in the serum ALT and AST activities and hepatic iNOS expression in response to the LPS challenge were significantly attenuated. Thus, hydrolyzable tannins in ELE ameliorate LPS-induced liver injury. |
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Keywords: | Eucalyptus globulus Endotoxin Hepatoprotective effect Anti-inflammation Gallic acid Ellagic acid Thiobarbituric acid-reactive substance |
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