Source
U.S. Citrus and Subtropical Products Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 600 Avenue S, Northwest, Winter Haven, Florida 33881, USA. John.Manthey@ars.usda.gov
Abstract
The anti-inflammatory properties of 3',4',3,5,6,7,8-heptamethoxyflavone (HMF), a citrus polymethoxylated flavone, were studied in the bacterial lipopolysaccharide (LPS)-challenge/tumor necrosis factor-alpha (TNFalpha) response in mice and in the carrageenan/paw edema assay in rats. In each of these trials, HMF administered by intraperitoneal (ip) injection exhibited anti-inflammatory activity, whereas HMF administered orally (po) produced no effects. The inhibition observed in the LPS-challenge/TNFalpha assay correlated with the HMF levels in the blood sera of mice dosed (ip) with either 33 or 100 mg/kg body weight. Low levels of HMF (0.035 +/- 0.024 ppm) were detected in the blood sera of mice dosed orally [100 mg of HMF (suspended in vegetable oil)/kg], whereas ip injection led to higher levels (0.517 +/- 0.051 ppm). This may account for the different levels of anti-inflammatory effects observed in mice following ip vs oral HMF administration. HMF metabolites, including a number of mono- and di-demethylated HMF metabolites and their glucuronic acid conjugates, were also detected, but results of these studies suggest that the glucuronidated metabolites of HMF are inactive in these inflammation models.