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Synthesis of [18F]2B-SRF101: A Sulfonamide Derivative of the Fluorescent Dye Sulforhodamine 101

[ Vol. 10 , Issue. 3 ]

Author(s):

Ingrid Kreimerman, Williams Porcal, Silvia Olivera, Patricia Oliver, Eduardo Savio* and Henry Engler   Pages 212 - 220 ( 9 )

Abstract:


Background: The red fluorescent dye Sulforhodamine 101 (SR101) has been used in neuroscience research as a useful tool for staining of astrocytes, since it has been reported as a marker of astroglia in the neocortex of rodents in vivo. The aim of this work is to label SR101 with positron emission radionuclides, in order to provide a radiotracer to study its biological behavior. This is the first attempt to label SR101 by [18F], using a chemical derivatization via a sulfonamidelinker and a commercially available platform.

Methods: The synthesis of SR101 N-(3-Bromopropyl) sulfonamide and SR101 N-(3- Fluoropropyl) sulfonamide (2B-SRF101) was carried out. The radiosynthesis of SR101 N-(3- [18F]Fluoropropyl) sulfonamide ([18F]2B-SRF101) was performed in a TRACERlab® FX-FN. Different labeling conditions were tested. Three pilot batches were produced and quality control was performed. Lipophilicity, plasma protein binding and radiochemical stability of [18F]2BSRF101 in final formulation and in plasma were determined.

Results: SR101 N-(3-Bromopropyl) sulfonamide was synthetized as a precursor for radiolabeling with [18F]. 2B-SRF101 was prepared for analytical purpose. [18F]2B-SRF101 was obtained with radiochemical purity of (97.0 ± 0.6%). The yield of the whole synthesis was (11.9 ± 1.7 %), nondecay corrected. [18F]2B-SRF101 was found to be stable in final formulation and in plasma. The octanol-water partition coefficient was (Log POCT = 1.88 ± 0.14). The product showed a high percentage of plasma protein binding.

Conclusions: The derivatization of SR101 via sulfonamide-linker and the first radiosynthesis of [18 F]2B-SRF101 were performed. It was obtained in accordance with quality control specifications. In vitro stability studies verified that [18F]2B-SRF101 was suitable for preclinical evaluations.

Keywords:

Fluorine-18, Positron emission tomography, radiopharmaceutical, Sulforhodamine 101, sulfonamide, astrocyte marker.

Affiliation:

Uruguayan Centre of Molecular Imaging (CUDIM) Radiopharmacy Department, Montevideo, Uruguayan Centre of Molecular Imaging (CUDIM) Radiopharmacy Department, Montevideo, Instituto de Investigaciones Biologicas, Clemente Estable, Montevideo, Uruguayan Centre of Molecular Imaging (CUDIM) Radiopharmacy Department, Montevideo, Ricaldoni 2010, Postal Code 11.600, Montevideo, Uruguayan Centre of Molecular Imaging (CUDIM) Radiopharmacy Department, Montevideo

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