The progressive deposition of amyloid-β protein (Aβ) in the brain is a pathologic feature of Alzheimer's disease (AD). We evaluated forest bioresources whether to have an efficacy for AD. The screening was performed by Aβ ELISA using H4 cell line stably expressing human APP695 with the Swedish mutation. We focused on leaf extracts X and Ursolic acid (UA) contained in the leaf extracts X through the in vitro screening.
 To investigate the effect of leaf extracts X and UA on neurological functions, C57BL/6 male mice were received at our facility at 5 weeks of age and were fed ad libitum a powdered diet containing leaf extracts X or UA for 12 months. Aβ42 levels in the brains were measured by the standard ELISA. The leaf extracts X increased Aβ42 at 3 months and decreased at 12 months, which were compared to control mice. UA also decreased Aβ42 at 12 months. Compared to the control mice, these mice showed a meaningful higher performance than the control mice in Y-maze tests. These results indicate that leaf extracts X and UA may be useful for the development of new drugs to treat AD.