Polymethoxylated Flavonoids Protect Against Liver Injury

Byron's Comments:

More evidence of the protective effects of nobiletin and tangeretin.

Study Title:

Hepatoprotective effects of flavonoids from shekwasha (Citrus depressa) against D-galactosamine-induced liver injury in rats.

Study Abstract:

We attempted to isolate the constituent(s) responsible for the suppressive effect of the juice of shekwasha, a citrus produced in Okinawa Prefecture, on D-galactosamine (GalN)-induced liver injury in rats. Liver injury-suppressive activity, as assessed by plasma alanine aminotransferase and aspartate aminotransferase activities, was found only in the fraction that was extracted with n-hexane when three fractions were added to the diet and fed to rats. Of five compounds isolated from the n-hexane-soluble fraction by silica gel column chromatography, three compounds had liver injury-suppressive effects when five compounds were singly force-fed to rats at a level of 300 mg/kg body wt 4 h before the injection with GalN. The structures of the three active compounds were determined as 3’,4’,5,6,7,8-hexamethoxyflavanone (citromitin), 4’,5,6,7,8-pentamethoxyflavone (tangeretin) and 3’,4’,5,6,7,8-hexamethoxyflavone (nobiletin), which are known flavonoids mainly existing in citrus. Nobiletin, the most important compound in the n-hexane-soluble fraction, also had suppressive effects on liver injuries induced by carbon tetrachloride, acetaminophen and GalN/lipopolysaccharide (LPS) in addition to liver injury induced GalN. Nobiletin suppressed GalN/LPS-induced increases in plasma tumor necrosis factor (TNF)-alpha and nitric oxide (NO) concentrations and hepatic mRNA levels for inducible NO synthase and DNA fragmentation. These results suggest that nobiletin suppressed GalN/LPS-induced liver injury at least by suppressing the production of both TNF-alpha and NO. The results obtained here indicate that the hepatoprotective effect of shekwasha juice is mainly ascribed to several polymethoxy flavonoids included in the juice.

Study Information:

Akachi T, Shiina Y, Ohishi Y, Kawaguchi T, Kawagishi H, Morita T, Mori M, Sugiyama K. Hepatoprotective effects of flavonoids from shekwasha (Citrus depressa) against D-galactosamine-induced liver injury in rats. J Nutr Sci Vitaminol (Tokyo). 2010 January 56(1):60-7.
The United Graduate School of Agricultural Science, Gifu University, Gifu, Japan.

Full Study:

http://www.jstage.jst.go.jp/article/jnsv/56/1/60/_pdf