Patent ID: 8664009

Claim:
A method of diagnosing a trypanasomatid infection in a patient by detecting a dicysteine trypanathione, comprising the steps of: (a) contacting a sample of the patient with an arsenical fluorescent dye that exhibits a detectable increase or shift in fluorescence when the arsenic of the dye reacts with the cysteines of the trypanathione; and (b) detecting the increase or shift in fluorescence as an indication of the presence of the trypanathione and the trypanasomatid infection; wherein the dye is a substituted, optionally hydro-, optionally hetero-, monoarsenical anthracene compound comprising a 4′ rotation blocking group and a 5′ arsenic, and that exhibits a detectable increase or shift in fluorescence when the arsenic reacts with two thiols of a rotation-blocking binding target molecule, the compound having the structure I: wherein: R1 is O, S, NRα, or CRα 2 ; R2 is C or N; R3 is optionally substituted-, optionally hetero-alkyl, optionally substituted-, optionally hetero-alkenyl, optionally substituted-, optionally hetero-alkynyl, optionally substituted-, optionally hetero-aryl, or optionally substituted-, optionally hetero-alkoxy; R4 and R5 are independently carbonyl, carbonothioyl, NRα 2 , ORα, or SRα; R6 and R7 are Rα, halide, ORα, NRα 2 , ORα, SRα, or nitro (—NO 2 ); R8 and R9 are Rα, halide, ORα, NRα 2 , ORα, SRα, or nitro (—NO 2 ); R10 is a rotational blocking group; R11 is an arsenic protecting group displaced by reaction of the arsenic with the thiols of the target molecule; Rα groups are independently H, optionally substituted-, optionally hetero-alkyl, optionally substituted-, optionally hetero-alkenyl, optionally substituted-, optionally hetero-alkynyl, optionally substituted-, optionally hetero-aryl, or optionally substituted-, optionally hetero-alkoxy; wherein one or more of the pairs R4-R6, R6-R8, R5-R7, and R7-R9 may be covalently joined in one or more rings; and tautomers, anhydrides and salts of the compound.