Fluorescent rhodanine-3-acetic acids visualize neurofibrillary tangles in Alzheimer’s disease brains

• Published in: Bioorganic & medicinal chemistry Vol. 21; no. 17; pp. 5139 - 5144
• Main Authors: Anumala, Upendra Rao, Gu, Jiamin, Lo Monte, Fabio, Kramer, Thomas, Heyny-von Haußen, Roland, Hölzer, Jana, Goetschy-Meyer, Valerie, Schön, Christian, Mall, Gerhard, Hilger, Ingrid, Czech, Christian, Herms, Jochen, Schmidt, Boris
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 01.09.2013; Elsevier
• Subjects: Acetates - chemical synthesis; Acetates - chemistry; Acetates - toxicity; acids; Alzheimer disease; Alzheimer Disease - metabolism; Alzheimer Disease - pathology; Alzheimer’s disease; amyloid; Amyloid beta-Peptides - chemistry; Amyloid beta-Peptides - metabolism; Animals; binding capacity; binding sites; Biochemistry & Molecular Biology; brain; Brain - metabolism; Brain - pathology; carcinoma; Cell Line, Tumor; Cell Survival - drug effects; Chemistry; Chemistry, Medicinal; Chemistry, Organic; Cytotoxicity; Danio rerio; Embryo, Nonmammalian - drug effects; fluorescence; Fluorescence imaging; Fluorescent Dyes - chemical synthesis; Fluorescent Dyes - chemistry; Fluorescent Dyes - toxicity; histopathology; Humans; image analysis; in vitro studies; in vivo studies; inhibitory concentration 50; Life Sciences & Biomedicine; liver; Microscopy, Fluorescence; Neurofibrillary tangles; patients; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Pharmacology & Pharmacy; Physical Sciences; Rhodanine - chemistry; Science & Technology; tau Proteins - chemistry; tau Proteins - metabolism; Zebrafish; Zebrafish - growth & development; Zebrafish; Cytotoxicity; Neurofibrillary tangles; Fluorescence imaging; Alzheimer’s disease; DESIGN; PATHOLOGY; PLAQUES; FLORBETAPIR; PROBES; TAU AGGREGATION INHIBITORS; FIBRILS; IN-VIVO; Alzheimer's disease; DERIVATIVES; PET
• ISSN: 0968-0896; 1464-3391
• DOI: 10.1016/j.bmc.2013.06.039

There is a high demand for the development of an imaging agent for neurofibrillary tangles (NFTs) detection in Alzheimer’s diagnosis. In the present study, a series of rhodanine-3-acetic acids was synthesized and evaluated for fluorescence imaging of NFTs in brain tissues of AD patients. Five out of seven probes have shown excellent binding affinity to NFTs over amyloid plaques in the Thiazine red R displacement assay. However, the selectivity in this in vitro assay is not confirmed by the histopathological evaluation, which indicates significant differences in the binding sites in the assays. Probe 6 showed binding affinity (IC50=19nM) to tau aggregates which is the highest among this series. Probes 2, 3, 4 and 5 display IC50 values of lower than 100nM to tau aggregates to displace Thiazine red R. Evaluation of the cytotoxicity of these five probes with human liver carcinoma cells revealed that these compounds excert negligible cytotoxicity. The in vivo studies with zebrafish embryos confirmed negligible cytotoxicity at 24 and 72h post fertilization.