Citrus polymethoxylated flavones: blood-lipid lowering and anticancerogenic effects

Polymethoxylated flavones (PMF) are primarily found in Citrus species. Peel oils contain up to 6 g/l, peels 8.5 g/kg and juices 0.04 g/l. Main PMF components are tangeretin (5,6,7,8,4'-pentamethoxy-flavonel and nobiletin (5,6,7,8,3',4'-hexamethoxyflavone). In Australia an extract containing 48 % PMFs is commercially available. Administered tangeretin (Tan) and nobiletin (Nob) are metabolized by the intestinal flora and in the liver by demethytation and hydroxylation of the intact flavone nucleus. Traces of both Tan and Nob, and their metabolites are excreted with the urine. The urinary excretion rate of the Tan metabolites is about 11% of the daily dose, the excretion rate of Tan in the faeces is 7% as Tan and 28 % as metabolites. In vivo and in vitro experiments with Tan and Nob have shown significantly reduced serum VLDL + LDL chollesterol and triacylglycerol in the presence of constant HDL cholesterol Levels. Fatty acid beta-oxidation as well as the differentiation and Lipolysis in adipocytes increase. In human cell cultures and in mice Tan and Nob have been found to inhibit carcinoma cell growth.