Alzheimer's disease (AD) is an age-dependent neurodegenerative disease. It is a multifactorial disease and despite intensive research, the precise reasons of AD are still unknown. However, it is known that AD is characterized by the presence of proteinaceous aggregates (amyloid plaques), which are mainly composed of so called amyloid beta (A?) peptides. Numerous genetic and biochemical studies suggest that aggregation of these A? peptides, thereby formation of neurotoxic amyloid fibrils and plaques, is a cause of neurodegeneration. Hence, it is very important to find compounds that can inhibit production and/or aggregation of A? peptides, being therefore attractive candidates as therapeutics for the prevention and/or treatment of AD. During recent years a novel sensitive and fast high-throughput screening test employing MALDITOF MS, based on detection of monomeric synthetic A? peptides during their aggregation has been developed in Tallinn University of Technology. Aim of the present project is to continue the development of this in vitro screening test as well as application of this test for discovery and development of new potent inhibitors of amyloid fibril formation. For this, high throughput screening of variety of compounds will be performed in order to determine those capable to solubilize the amyloid plaques or inhibite the formation of amyloid fibrils, creating thus a possibility for development of disease modifying drugs for AD. Aggregation of A? will be studied by using mainly human A? 1-42 peptide, which is the most abundant component in AD plaques. Influence of different modifiers to its aggregation will be studied. For testing it is planned to use libraries of individual compounds as well as new libraries of natural compounds from medicinal herbs, obtained by bioseparation.