Bioactivity-guided Separation of the Active Compounds in Acacia pennata Responsible for the Prevention of Alzheimer's Disease

The objective of this study was to evaluate the health benefits of plants used in Thai food, specifically Acacia pennata Willd., in Alzheimer's prevention. A. pennata twigs strongly inhibited beta-amyloid aggregation. Bioactivitguided separation of the active fractions yielded six known compounds, tetracosane (1), 1-(heptyloxy)-octadecane (2), methyl tridecanoate (3), arborinone (4), confertamide A (5) and 4-hydroxy-1-methyl-pyrrolidin-2-carboxylic acid (6). The structures were determined by spectroscopic analysis. Biological testing revealed that tetracosane (1) was the most potent inhibitor of beta-amyloid aggregation, followed by 1-(heptyloxy)-octadecane (2) with IC50 values of 0.4 and 12.3 mu M. Methyl tridecanoate (3), arborinone (4) and 4-hydroxy-1 -methyl-pyrrolidin-2-carboxylic acid (6) moderately inhibited beta-amyloid aggregation. In addition, tetracosane (1) and methyl tridecanoate (3) weakly inhibited acetylcholinesterase (AChE). These results suggested that the effect of A. pennata on Alzheimer's disease was likely due to the inhibition of beta-amyloid aggregation. Thus A. pennata may be beneficial for Alzheimer's prevention.