Search for effective plant materials for Alzheimer's disease

Alzheimer's disease became a threatening disease. We performed an extensive screening for effective plant materials for dementia, especially Alzheimer's disease utilizing β-secretase, acetylcholinesterase and butyrylcholinesterase. As results, we found that some extracts obtained from spices used in Asian countries would be effective to Alzheimer's disease in long-term consumption. In addition, the active principles were revealed as various compounds including terpenes, phenylpropanoids, alkaloids and lignans¹⁾.

In this study, we have extended our screening source to ingredients of incence stick used in Japan. We have screened the ingredients consisting of the incence stick including star anise (fruit of Illicium verum), turmeric (rhizome of Curcuma longa), clove (bud of Syzygium aromaticum), patchouli (above ground part of Pogostemon cablin) and frankincense (rosin of Boswellia sp.) extracts showing 17.0, 26.4, 24.6, 31.7, and 24.4% of inhibitions, respectively, against acetylcholinesterase at 100 µg/ml. On the other hand, basal material of incence stick: hexane extract from leaf of Cryptomeria japonica showed 31.4% of inhibition at 100 µg/ml. Activity-guided purification of active principles led us to isolate kaur-16-ene, nezukol and ferruginol.

The heartwood of Chamaecyparis obtusa, a well-known conifer as C. japonica, was also tested for the inhibitory activity against acetylcholinesterase. Ethyl acetate extract of C. obtusa showed 37.7% on inhibition at 100 µg/ml. One of the active principles was determined as hinokinin.

These results suggest that aromatic materials can be a promising screening source for effective agents for therapy of Alzheimer's diseases.

[1] Murata K, Matsumura S, Yoshioka Y, Ueno Y, Matsuda H.: J. Nat. Med,69, 123 – 129 (2015).