Inhibition by Salix- Extracts and Phytodolor^Rof Copper-Catalyzed Oxidative Destructions

Reactive Oxygen Species, Copper Catalysis, Low Density Lipoprotein-Oxidation, Antioxidants, Salix-Extracts Oxidation of low density lipoprotein (LDL) by copper ions is strongly inhibited by different aqueous extracts (Salix spec (SE); Fraxinus-Solidago-Populus (Phytodolor^R)(PD)) in a concentration range between 4 and 7 μg/ml. 10 to 50 μm salicylic acid (SA) stimulate LDL- oxidation whereas higher concentrations (10 to 500 μm) show no effect. Likewise ethene release from 2-keto-4-methylthiobutyrate (KMB) is strongly inhibited by the above extracts in a reaction driven by dihydroxyfumarate (DHF) in the presence of copper ions. This system may represent some features of the diabetic situation where DHF as an endiole may stand for certain Amadori products. In order to find out whether the inhibitory effects are due to copper chelation we tested the copper-dependent conversion of photodynamic ethane release from α-linolenic acid into ethene formation. Copper chelation is apparently only partially involved in inhibition of copper-dependent oxidations and only at a certain concentration of extracts from Salix spec (SE) or extracts from Fraxinus-Solidago-Populus (Phytodolor^R)(PD).