Figure 1.

(a) Model of non-amyloidogenic and amyloidogenic processing of the amyloid precursor protein (APP) with subdivision into anabolism and catabolism of the neurotoxic APP cleavage product Aβ. The involved secretases and the resulting products are illustrated. (b) Chemical structures of xanthine (2,6-dihydroxypurine) and the analyzed methylxanthines (MTXs) caffeine (1,3,7-trimethylxanthine), theophylline (1,3-dimethylxanthine), theobromine (3,7-dimethylxanthine), pentoxifylline (3,7-dimethyl-1-(5-oxohexyl)purin-2,6-dion) and propentofylline (3-methyl-1-(5-oxohexyl)-7-propylpurine-2,6-dione). In red color the structural differences between the MTXs are highlighted.