Search for β-Secretase Inhibitors from Natural Spices

Abstract

The growing number of Alzheimer's disease (AD) patients prompted us to seek effective natural resources for the prevention of AD. We focused on the inhibition of β-secretase, which is known to catalyze the production of senile plaque. Sixteen spices used in Asian countries were selected for the screening. Among the extracts tested, hexane extracts obtained from turmeric, cardamom, long pepper, cinnamon, Sichuan pepper, betel, white turmeric and aromatic ginger showed potent inhibitory activities. Their active principles were identified as sesquiterpenoids, monoterpenoids, fatty acid derivatives and phenylpropanoids using GC-MS analyses. The chemical structures and IC 50 values of the compounds are disclosed. The results suggest that long-term consumption of aromatic compounds from spices could be effective in the prevention of AD.

Inhibitory Activities of Essential Oil Obtained from Turmeric and Its Constituents against β-Secretase

“…In our previous report, hexane and ethyl acetate extracts of Curcuma longa rhizomes showed high potency against β-secretase [1]. The active principles were determined as α-turmerone, βturmerone and ar-turmerone ( Fig.…”

“…There are only a few studies on the pharmacokinetic properties of turmerones, especially α-and β-turmerone [4] due to the difficulties of isolation and a shortage of the compounds available from natural sources. In fact, the isolation yield was very low in our previous study, possibly due to volatility [1]. Thus, the introduction of an original and efficient isolation method led to the isolation of α-and β-isomers and ar-type turmerones in a pure form that enabled testing to show whether the compounds would pass through the blood-brain barrier to reach the brain in an intact form.…”

“…We focused on the steam distillation method as a suitable extraction procedure for obtaining the essential oils and volatile compounds [3]. We utilized this method for C. longa rhizomes and showed that the extraction of turmerones is more efficient compared with the solvent extraction used previously [1]. Moreover, vacuum distillation could separate the contents of essential oil extracts obtained by steam distillation efficiently.…”

Screening of Spice Extracts Possessing Anti-Acetylcholinesterase Activity and Active Principle of Bitter Ginger, Rhizome of Zingiber zerumbet

“…The screening of various plant materials for the most suitable agents for long-term consumption was performed to obtain naturally originating inhibitors. Among them, turmerones showed relatively high inhibitory activities againt β-secretase at 39, 62 and 92 μM of IC 50 values for α-, β-and ar turmerones, respectively [1]. In addition, turmerones were shown to reach the brain in intact forms when administered orally [2].…”

Inhibitory Activities of Sesame Seed Extract and its Constituents against β-Secretase

“…In a screening study, we found that the sesame seed extract (Sesamum indicum) showed moderate inhibitory activities [2]. Among the tested extracts, ethyl acetate (EtOAc) extract showed the most potent inhibitory activity of 39% at 250 μg/mL.…”