Tolcapone Derivative (Tol-D) Inhibits Aß42 Fibrillogenesis and Ameliorates Aß42-Induced Cytotoxicity and Cognitive Impairment.

Abnormal aggregation and subsequent fibrillogenesis of amyloid-ß protein (Aß) can cause Alzheimer's disease (AD). Thus, the discovery of effective drugs that inhibit Aß fibrillogenesis in the brain is important for the treatment of AD. Our previous study has proven that tolcapone inhibits Aß fibrillogenesis and alleviates its cytotoxicity based on systematic in vitro and in vivo experiments. However, the severe hepatotoxicity of tolcapone seriously limits its further potential application in the treatment of AD. Herein, an inhibitory effect of a low-toxicity tolcapone derivative (Tol-D) on Aß fibrillogenesis was explored. Based on the thioflavin T fluorescence data, Tol-D inhibited Aß fibrillogenesis, and the inhibitory capacity increased with the increase of its concentrations with an IC50 of ∼8.99 µM. The results of cytotoxicity showed that Tol-D greatly reduced the cytotoxicity induced by Aß42 fibrillogenesis. Moreover, Tol-D significantly alleviated Aß deposits and extended the lifespan of nematodes in transgenic Caenorhabditis elegans models. Finally, Tol-D significantly relieved Aß-induced cognitive dysfunction in mice experiments. Overall, the above experimental results indicated that Tol-D is a novel candidate therapeutic compound for the treatment of AD.

Tolcapone derivative PCDNA inhibits Aβ42 fibrillogenesis and reduces its cytotoxicity / 药学学报

Abnormal aggregation of amyloid-β protein (Aβ) in brain plays a vital role in the occurrence of Alzheimer's disease (AD). Hence, inhibiting Aβ aggregation is one major tactic for therapy of AD. Previous studies have found that tolcapone can inhibit Aβ42 aggregation and reduce the cytotoxicity induced by Aβ42 aggregates, but clinical studies have found that tolcapone has strong liver toxicity. To reduce the liver toxicity of tolcapone, its side chain structure was modified to obtain its derivative phenethyl (E)-2-cyano-3-(3,4 dihydroxy-5-nitrobenzene)-acrylate (PCDNA). Thioflavin T (ThT) and atomic force microscopy (AFM) assays were used to explore the inhibitory effect of PCDNA on Aβ42 fibrillogenesis. The cytotoxicity assays were used to explore the inhibitory effect of PCDNA against the cytotoxicity induced by Aβ42 aggregates. In addition, the depolymerization effect of PCDNA on mature Aβ42 fibrils was also explored. Finally, molecular docking was used to explore the interaction between PCDNA and Aβ42 pentamer. These results lay the foundation for the study of the structural analogues of tolcapone as Aβ inhibitors.