PROCYANIDINS EXTRACTED FROM PINE BARK PROTECT ALPHA-TOCOPHEROL IN ECV-304 ENDOTHELIAL-CELLS CHALLENGED BY ACTIVATED RAW-264.7 MACROPHAGES -ROLE OF NITRIC-OXIDE AND PEROXYNITRITE

A co-culture system was used to study the effect of reactive nitrogen species (RNS) generated by RAW 264.7 macrophages grown on filters and activated by lipopolysaccharide and interferon-gamma, on the alpha-toc opherol levels in ECV 302 endothelial cells. The results indicate that : RNS generated by activated macrophages or by direct administration o f peroxynitrite lead to a significant loss of alpha-tocopherol in endo thelial cells; pre-incubation with procyanidin extracted from pine bar k (Pycnogenol) protects alpha-tocopherol of endothelial cells and enha nces by about 15% basal endogenous levels of alpha-tocopherol, These r esults demonstrate flavonoids participate in the cellular antioxidant network and suggest that Pycnogenol may play an important role in the protection of endothelium from oxidative stress induced by reactive ni trogen species. (C) 1998 Federation of European Biochemical Societies.