Vitamin A has Anti-Oligomerization Effects on Amyloid-β In Vitro

Article type: Research Article

Authors: Takasaki, Junichi^{a; 1} | Ono, Kenjiro^{a; 1} | Yoshiike, Yuji^b | Hirohata, Mie^a | Ikeda, Tokuhei^a | Morinaga, Akiyoshi^a | Takashima, Akihiko^b | Yamada, Masahito^{a; *}

Affiliations: [a] Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan | [b] Laboratory for Alzheimer's Disease, Brain Science Institute, Riken, Wako, Saitama, Japan

Correspondence: [*] Correspondence to: Masahito Yamada, MD, PhD, 13-1 Takara-machi, Kanazawa 920-8640, Japan. Tel.: +81 76 265 2290; Fax: +81 76 234 4253; E-mail: [email protected].

Note: [1] These authors contributed equally to this work.

Abstract: Inhibition of amyloid-β (Aβ) aggregation is an attractive therapeutic strategy for treatment of Alzheimer's disease (AD). We previously reported that vitamin A and β-carotene inhibit fibrillation of Aβ40 and Aβ42 (Ono et al, 2004, Exp Neurol). In this study, we firstly examined the effects of vitamin A (retinoic acid, retinol, and retinal), β-carotene, vitamin B2, vitamin B6, vitamin C, vitamin E, coenzyme Q10, and α-lipoic acid on oligomerization of Aβ40 and Aβ42 in vitro; vitamin A and β-carotene dose-dependently inhibited oligomerization of Aβ40 and Aβ42. Furthermore, retinoic acid decreased cellular toxicity by inhibition of Aβ42 oligomerization. Second, we analyzed how vitamin A inhibits Aβ aggregation by using fluorescence spectroscopy and thioflavin T assay with two Aβ fragments, Aβ1-16 and Aβ25-35. A fluorescence peak of retinoic acid was greatly restrained in the presence of Aβ25-35, and retinoic acid inhibited aggregation of Aβ25-35, but not of Aβ1-16, which suggest the specific binding of retinoic acid to the C-terminal portion of Aβ. Thus, vitamin A and β-carotene might be key molecules for prevention of AD.

Keywords: Alzheimer's disease, amyloid-β, oligomer, vitamin A

DOI: 10.3233/JAD-2011-110455

Journal: Journal of Alzheimer's Disease, vol. 27, no. 2, pp. 271-280, 2011