This review focuses on recent developments in the use of natural products as therapeutics for Alzheimer’s disease. Compounds span a diverse array of structural classes and are organized according to their mechanism of action, with the focus primarily on the major hypotheses. Overall, the review discusses more than 180 compounds and summarizes 393 references.

Bioassay-guided fractionation of an extract prepared from the fruits of Cordia sebestena has led to the isolation of sebestenoids A-D (1-4). The structures of these new phenylpropanoid esters were elucidated on the basis of extensive NMR experiments and mass spectroscopic measurements. Compounds 1-4 exhibited moderate inhibition of the aspartic protease BACE1.

Despite the long history of drug discovery from natural sources, the marine environment, which covers 70% of the Earth’s surface, is still relatively unexplored. Intense competition for limited resources drives the evolution of specific and potent chemical defenses distinct from their terrestrial counterparts. Based on this rationale, we recently began screening extracts derived from marine invertebrate and cyanobacterial samples for BACE-1 inhibitors in a chemiluminescent enzyme-fragment complementation (EFC) assay. The results of this broad screening are presented here, along with our progress towards the development of a secondary LC-MS homogeneous affinity assay. Incubation of the extracts active in the EFC assay with BACE1, subsequent isolation of the enzyme-inhibitor complex and then analysis of the small molecule inhibitor by LC-MS rapidly links a chemical structure to biological activity. This approach enables the rapid target-orientated discovery of BACE-1 inhibitors from marine sources.