Synthesis of [18F]2B-SRF101: A sulfonamide derivative of the fluorescent dye Sulforhodamine 101.

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 behaviour. This study is the first attempt to label SR101 with [18F], using a chemical derivatization via a sulfonamide-linker and a commercially available platform. Methods The synthesis of SR101 N-(3-Bromopropyl) sulfonamide and SR101 N-(3-Fluoropropyl) sulfonamide (2B-SRF101) were carried out. The radiosynthesis of SR101 N-(3-[18F]Fluoropropyl) sulfonamide ([18F]2B-SRF101) was performed in a TRACERlab® FX-FN. Different labelling conditions were tested. Three pilot batches were produced and quality control was performed. Lipophilicity, plasma protein binding and radiochemical stability of [18F]2B-SRF101 in final formulation and in plasma were determined. Results SR101 N-(3-Bromopropyl) sulfonamide was synthetized as a precursor for radiolabelling 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 %), non-decay corrected. [18F]2B-SRF101 was 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 [18F]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. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Citation

Ingrid Kreimerman, Williams Porcal, Patricia Oliver, Eduardo Savio, Henry Engler. Synthesis of [18F]2B-SRF101: A sulfonamide derivative of the fluorescent dye Sulforhodamine 101. Current radiopharmaceuticals. 2017 Sep 27

PMID: 28956517

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