Azure A analogs as imaging agents and probes for diagnosis of diseases related to amyloid accumulation. Jpn. Kokai Tokkyo Koho JP 2000344685, 2000

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... The most famous derivative of PTZs is methylene blue (MB) (3,7-bis (dimethylamino) phenazathionium chloride), which is used as a drug with complex pharmacology and multiple clinical indications. Among PTZs derivatives are the Azure family, which contains Azure A, Azure B, and Azure C. Azure dyes have been used in diagnosis and treatment areas particularly in diagnosis of amyloid accumulation related diseases 6 , neurodegenerative diseases 7 , treatment of avian influenza virus 8 , oral cavity infection 9 , and protozoan infections 10 , in addition to the important role in pathological tau-tau association in Alzheimer disease [11][12][13] . Azure A (N 0 ,N 0 -dimethylphenothiazin-5-ium-3,7-diamine chloride) ( Figure 1) which is one of the tricyclic phenothiazine synthetic derivative dyes has been shown to prevent Tau aggregation in vitro 14,15 . ...
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Azure-A is one of the phenothiazines (PTZs) derivatives which for decades have been used as antipsychotic drugs due to good lipophilic characteristics which enable them to pass through the blood brain barrier (BBB), besides the important property of enabeling investigation of the pathological forms of aggregated tau protein found in the neurons of the central nervous system. Radioiodination of Azure-A was carried out via an electrophilic substitution reaction using chloramine-T as oxidizing agent. The influence of various reaction parameters and conditions on radioiodination efficiency was investigated and a high radiochemical yield of 92.07± 0.9 % was obtained. An in vitro cytotoxicity study of iodinated Azure-A on three cell lines (HCT-116, human colon carcinoma cell line; Hep-G2, liver carcinoma cell line and HFB-4, normal human melanocytes) was carried out and the data revealed that ioiodinated Azure A has no to very low toxic effect. The in vivo biodistribution study of 131 I-Azure A showed a high brain uptake of 6.15±0.09 % injected dose/g tissue organ at 30 min post-injection and its retention in brain remained high up to 2 h, whereas the clearance from the body appeared to proceed via the renal system. The experimental data were confirmed by the molecular docking studies to predict the effect of radioiodination on the binding affinity of the parent molecule (Azure A) to tau paired helical filaments (PHFs). Both ligands showed better binding to S2 and S3 pockets of (PHFs). Consequently, radioiodinated Azure A seems to be a good candidate as an imaging agent for taupathies such as Alzheimer's disease, Chronic traumatic encephalopathy, Corticobasal degeneration. Furthermore, it could be a very potent theranostics agent for brain tumors.
... AZB is used in the staining of DNA, blood products, epithelial tissues, proteins, viruses, lignin, melanin, keratin fibers and malaria-infected cells [5]. It is also used in the diagnosis of amyloid accumulation related diseases [6], malignant melanoma, detection of oral cancer, oral cavity infection and neuro-degenerative diseases, etc., [7][8][9]. ...
A complete, up-to-date resource of information on more than 200 dyes and stains Handbook of Biological Dyes and Stains is the most comprehensive volume available on the subject, covering all the available dyes and stains known to date in the literature for use in biology and medicine. Top dye expert Dr. Ram Sabnis organizes the compounds alphabetically by the most commonly used chemical name. He presents an easy-to-use reference complete with novel ideas for breakthrough research in medical, biological, chemical, and related fields. This is the first book to give the CAS registry number, chemical structure, Chemical Abstracts index name, all other chemical names, Merck Index number, chemical/dye class, molecular formula, molecular weight, physical form, solubility, melting point, boiling point, pH range, color change at pH, pKa, absorption, and emission maxima of dyes and stains, as well as to provide access to synthesis procedures (lab scale and industrial scale) of dyes and stains. This user-friendly handbook also features references on safety, toxicity, and adverse effects of dyes and stains on humans, animals, and the environment, including: • acute/chronic toxicity • aquatic toxicity • carcinogenicity • cytotoxicity • ecotoxicity • genotoxicity • hepatotoxicity • marine toxicity • mutagenicity • nephrotoxicity • neurotoxicity • oral toxicity • phototoxicity • phytotoxicity The use of biological dyes and stains has extremely high potential in today's business environment. This makes Handbook of Biological Dyes and Stains a convenient, must-have reference. Its staining, biological, and industrial applications make it a vital resource for industrial and academic researchers; the book also serves as a valuable desktop reference for medical professionals, biologists, chemists, chemical/optical engineers, physicists, materials scientists, intellectual property professionals, students, and professors.
The thermodynamics of the reactions of the two phenothiazinium dyes azure A and azure B with the three double stranded ribonucleic acids, poly(A).poly(U), poly(C).poly(G), poly(I).poly(C) were investigated using DSC and ITC. The bound dyes stabilized the RNAs against thermal strand separation. The binding of azure A to the RNAs was predominantly enthalpy dominated while the binding of azure B was favoured by both negative enthalpy and favourable entropy changes. Although electrostatic interaction had a significant role in the binding, non-polyelectrolytic forces dominated the binding process. The negative values of heat capacity changes for the binding suggested a substantial hydrophobic contribution to the binding process. The overall binding affinity of both the dyes to the RNAs varied in the order, poly(A).poly(U) > poly(C).poly(G) > poly(I).poly
This manuscript presents spectroscopic characterization of the interaction of two phenothiazinium dyes, azure A and azure B with double stranded (ds) ribonucleic acids, poly(A).poly(U), poly(C).poly(G) and poly(I).poly(C). Absorbance and fluorescence studies revealed that these dyes bind to the RNAs with binding affinities of the order 10(6)M(-1) to poly(A).poly(U), and 10(5)M(-1) to poly(C).poly(G) and poly(I).poly(C), respectively. Fluorescence quenching and viscosity data gave conclusive evidence for the intercalation of the dyes to these RNA duplexes. Circular dichroism results suggested that the conformation of the RNAs was perturbed on interaction and the dyes acquired strong induced optical activity on binding. Azure B bound to all the three RNAs stronger than azure A and the binding affinity varied as poly(A).poly(U)>poly(C).poly(G)>poly(I).poly(C) for both dyes. Copyright © 2015. Published by Elsevier B.V.
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