Structural and Mechanistic Insights into Development of Chemical Tools to Control Individual and Inter‐Related Pathological Features in Alzheimer's Disease

Abstract

To elucidate the involvement of individual and inter-related pathological factors [i.e., amyloid-β (Aβ), metals, and oxidative stress] in the pathogenesis of Alzheimer’s disease (AD), chemical tools have been developed. Characteristics required for such tool construction, however, have not been clearly identified; thus, the optimization of available tools or new design has been limited. Here, key structural properties and mechanisms that can determine tools’ regulatory reactivities with multiple pathogenic features found in AD are reported. A series of small molecules was built up through rational structural selection and variations onto the framework of a tool useful for in vitro and in vivo metal–Aβ investigation. Variations include: (i) location and number of an Aβ interacting moiety; (ii) metal binding site; and (iii) denticity and structural flexibility. Detailed biochemical, biophysical, and computational studies were able to provide a foundation of how to originate molecular formulas to devise chemical tools capable of controlling the reactivities of various pathological components through distinct mechanisms. Overall, this multidisciplinary investigation illustrates a structure–mechanism-based strategy of tool invention for such a complicated brain disease.

Minor Structural Variations of Small Molecules Tune Regulatory Activities toward Pathological Factors in Alzheimer's Disease

“…As summarized in Table 1, the compounds ( 5 , 6 , 8 , and 9 ) designed to undergo oxidation have similar or lower computed IPs to the previously determined values for 1 , [5] 3 , [5] 4 , [5] and L2-b [8] suggesting that 1 , 3–6 , 8 , and 9 can produce radicals to be necessary for activity. Furthermore, as expected, the computational studies indicate that 7 , along with 2 , are more difficult to be oxidized than the other compounds (Table 1).…”

“…This could suggest that 5 may mediate the formation of NMR-invisible oligomers. This is in contrast to L2-b which demonstrates larger changes in the NMR spectra of Zn II -Aβ [7b,8] denoting that L2-b can directly interact with Zn II -Aβ possibly forming a ternary complex and subsequently control the Zn II -Aβ aggregation pathways.…”

Calprotectin influences the aggregation of metal-free and metal-bound amyloid-β by direct interaction

“…S6 and S7, ESI †). An anƟ-Aβ 40 antibody (6E10) 74,75 was employed to visualize Aβ 40 , an anti-S100A9 antibody was used to detect CP-Ser and CP-Ser ∆∆ , and Coomassie blue staining was employed to indicate S100B and S100B ∆ . Gel electrophoresis was conducted in running buffer containing 1% SDS to mobilize protein samples through the gel matrix.…”

“…All experiments with Aβ were performed according to previously published methods. 74,75,[82][83][84] Aβ peptides were dissolved in ammonium hydroxide (NH 4 OH, 1% v/v, aq), aliquoted, lyophilized, and stored at −80 °C. A stock soluƟon (ca.…”

“…200 µM) was prepared by dissolving Aβ in NH 4 OH (1% w/v, aq, 10 µL) followed by dilution with ddH 2 O, as reported previously. 74,75,[82][83][84] The Aβ 40 concentration was determined by measuring the absorbance of the solution at 280 nm (ε = 1450 M -1 cm -1 for Aβ 40 ; ε = 1490 M -1 cm -1 for Aβ 42 ). HEPES [4-(2hydroxyethyl)-1-piperazineethanesulfonic acid; 20 mM], pH 7.4 (for metal-free and Zn(II) samples) and pH 6.6 (for Cu(II) samples), 150 mM NaCl was used for the studies.…”