Hee Kim ,^†‡ Byeoung-Soo Park ,^†§ Kwang-Geun Lee ,^∥ Cheol Yong Choi ,^⊥ Sung Sik Jang ,^§ Young-Ho Kim ,^*‡ and Sung-Eun Lee ^*#

 

^‡ Digitalbiotech, Inc., Sin Gil Dong 1227, An San City, Kyong Gi Do 425-839, Korea, ^§ School of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Korea, ^∥ Department of Food Science and Technology, Dongguk University, Chung-gu, Seoul 100-715, Korea, ^⊥ Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Korea, and ^# Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, Hawaii 96822 

 

^* To whom correspondence should be addressed.

^† Authors equally contributed to this paper.

Abstract

β-Amyloid (βA)-induced oxidative toxicity on neuronal cells is a principal route in Alzheimer's disease (AD), and its toxicity occurs after fibril formation. Inhibitory or promoting effects of naturally occurring compounds on βA fibril formation were evaluated. Among 214 tested compounds, curcuminoids, flavone type flavonoids, and naphthoquinones were shown to be potent inhibitors of βA fibrilization. The addition of the curcuminoids, curcumin, demethoxycurcumin, and bisdemethoxycurcumin strongly inhibited βA fibril formation. Flavonoids such as quercetin, rhamnetin, and fisetin strongly inhibited βA fibril formation. Limonoids, cinnamic acids, and catechins enhanced fibril formation in vitro. Anthothecol possessed the most enhancing activity on fibril formation of the compounds tested. On the other hand, it was found that curcuminoids showed cytotoxicity with the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay and did not protect HT22 murine neuroblastoma cells from βA(25-35) insult. Two flavone type flavonoids, morin and quercetin, exhibited no cytotoxicity and strongly protected HT22 murine neuroblastoma cells from βA(25-35) oxidative attack. Conclusively, morin or quercetin could be a key molecule for the development of therapeutics for AD. 

 

Keywords: Curcumioids; flavonoids; Alzheimer's disease; β-amyloid; HT22 murine neuroblastoma cell; bA burden assay