Chemico-Biological Interactions 186 (2010) 16–23 Contents lists available at ScienceDirect Chemico-Biological Interactions journal homepage: www.elsevier.com/locate/chembioint Anti-amyloidogenic effect of AA3E2 attenuates -amyloid induced toxicity in SK-N-MC cells Hamed Shaykhalishahi a , Mohammad Taghizadeh a , Razieh Yazdanparast a,∗ , Young-Tae Chang b a Institute of Biochemistry and Biophysics, P. O. Box 13145-1384, University of Tehran, Enghelab Ave, Tehran, Iran b Department of Chemistry, NUS MedChem Program of Life Sciences Institute, National University of Singapore, Singapore 117543, Singapore article info Article history: Received 17 January 2010 Received in revised form 14 March 2010 Accepted 23 March 2010 Available online 30 March 2010 Keywords: AA3E2 Anti-amyloidogenic A1–42 fibril Alzheimer’s disease Docking abstract -Amyloid peptide (A) is believed to play a recognized role in pathogenesis of Alzheimer’s disease (AD). Self-association of A peptide into amyloid fibrils causes neurotoxicity. Compounds capable of interfering with A–A interaction through binding to nucleation sites can inhibit A amyloidogenesis and A- induced cytotoxicity. AA3E2 is a triazine-derivative whose anti-amyloidogenic ability has previously been established. In the present study, we evaluated the protective effect of AA3E3 against A 1–42 -induced toxicity in SK-N-MC cell line. The cell exposure to the co-incubated A 1–42 with AA3E2 decreased the cell viability loss dose-dependently, compared to cells exposed to A 1–42 fibrils. Co-incubation with AA3E2 also attenuated the ROS production, activation of caspase-3 and the extent of apoptotic cell death induced by A 1–42 fibril. Moreover, the 3D structure of the molecular associates between A 1–42 and AA3E2 were theoretically determined by docking studies. Our docking data indi- cated that AA3E2 inhibits the formation of A fibril likely via binding to the nucleation site within the hydrophobic region of A (KLVFF). These observations provide the background for future design of more elegant -breaking agents for dissolution of A fibrillar aggregates. © 2010 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Alzheimer’s disease (AD) is the most common cause of demen- tia and the fifth leading cause of death among Americans aging 65 and more with an afflicting rate of 70 s [1]. In the absence of effec- tive therapeutic approaches, more than 25 million people would be expected to be affected by AD in the near future [2]. One of the histological hallmarks of AD is the presence of brain senile plaques. The major constituent of these fibrillar plaques is a self-aggregating peptide named -amyloid peptide (A) [3]. The A is generated by the successive action of two proteases, - and -secretases, on the amyloid precursor protein (APP) [4]. The most abundant variants of A found in AD, are A 1–40 and A 1–42 containing 40 and 42 amino acids, respectively. A 1–42 is the dominant form in senile plaques and forms amyloid fibrils more rapidly than A 1–40 [5]. According to amyloid cascade hypothesis, the fibrillar A aggregates induce a cascade of events that lead to neuronal cell death [6]. The A peptide is rich in hydrophobic regions of -sheet structures which forms strong A–A intermolecular -sheet interactions, leading to fibril formation [7]. Regarding this fact, it would be logical to design therapeutic approach to disrupt the A–A interactions as ∗ Corresponding author. Tel.: +98 21 66956976; fax: +98 21 66404680. E-mail address: yazdan@ibb.ut.ac.ir (R. Yazdanparast). a means of attenuating the cytotoxicity of A aggregates [8–12]. In recent years, numerous approaches have been developed for efficient high-throughput screening of fibril inhibitors and beta- sheet breaker compounds [13,14]. AA3E2 is a triazine-derivative (Scheme 1A) whose beta-sheet breaking activity has been demon- strated by Kim et al. [13]. In addition, we have recently reported on the protective effect of AA3E2 against A fibril in SK-N-MC cell line through its anti-oxidant capacity [15], likely via its inhibitory effect against hydrogen peroxide cytotoxicity [16]. In this investigation, we were interested to further re-evaluate the molecular interac- tion of AA3E2 structure with the molecular region of the target using docking approaches. Our results clearly indicated that AA3E2 interacts with a hydrophobic region of the target A molecule hav- ing the following sequence, KLVFF, and this interaction might be the cause of lower cytotoxicity of the A aggregates. 2. Materials and methods 2.1. Materials The cell culture medium (RPMI 1640) and penicillin– streptomycin were purchased from Gibco BRL (Life technol- ogy, Paisley, Scotland). Fetal bovine serum (FBS) was obtained from Jahad Daneshgahi (Tehran, Iran). The culture plates were obtained from Nunc (Denmark). Ethidium bromide (EtBr) and 0009-2797/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.cbi.2010.03.042