Design of nonapeptide LVFFARKHH: A bifunctional agent against Cu2+‐mediated amyloid β‐protein aggregation and cytotoxicity

Dysfunctional accumulation of amyloid β‐protein (Aβ) mediated by Cu²⁺ exhibits higher neurotoxicity and accelerates the progress of Alzheimer's disease, so inhibition of Cu²⁺‐mediated Aβ aggregation and cytotoxicity has been considered as a therapeutic strategy for the disease. Herein, a nonapeptide was designed by linking HH to the C‐terminus of a peptide inhibitor of Aβ aggregation, LVFFARK (LK7). We found that the nonapeptide, LK7‐HH, possessed dual functionality, including enhanced inhibition capability on Aβ aggregation as compared to LK7, and chelating Cu²⁺ with a dissociation constant of 5.50 μM. This enabled LK7‐HH to arrest the generation of reactive oxygen species catalyzed by Cu²⁺ or Cu²⁺‐Aβ complex, and to inhibit Cu²⁺‐induced Aβ aggregation. Moreover, in contrast with the cytotoxicity of LK7 aggregates, LK7‐HH was biocompatible because HH conjugation made its aggregation behavior different from LK7. Thus, LK7‐HH efficiently suppressed Cu²⁺‐mediated Aβ aggregation and cytotoxicity. An equimolar concentration of LK7‐HH increased cell viability from 50% to 90% when treating Aβ₄₀‐Cu²⁺ complexes. The results provided insights into the roles of HH in enhancing the inhibition of Aβ and Cu²⁺‐induced Aβ aggregations, in eliminating Cu²⁺‐induced cytotoxicities by arresting generation of reactive oxygen species, and in making the peptide biocompatible. Therefore, this work would contribute to the design of potent peptide‐based inhibitors of Cu²⁺‐mediated Aβ aggregation and cytotoxicity.