title: Fluorinated isatin derivatives. Part 2. New N-substituted 5-pyrrolidinylsulfonyl isatins as potential tools for molecular imaging of caspases in apoptosis.
abstract: Caspases are responsible for the execution of the cell death program and are potentially suitable targets for the specific imaging of apoptosis in vivo. A series of N-1-substituted analogues of the small molecule nonpeptide caspase inhibitor (S)-5-[1-(2-methoxymethylpyrrolidinyl)sulfonyl]isatin (1), which may be useful for the development of caspase-targeted radioligands, were synthesized and their inhibition potencies were evaluated in vitro. Two of the most powerful techniques to introduce fluorine into organic compounds, viz, bromofluorination of olefins and fluorohydrin synthesis by ring-opening of epoxides, were used. Most of the target compounds are potent inhibitors of the two effector caspases-3 and -7. Furthermore, the (18)F-radiolabeled model compound (S)-1-[4-(1-[(18)F]fluoro-2-hydroxyethyl)benzyl]-5-[1-(2-methoxymethyl-pyrrolidinyl)sulfonyl]isatin ([(18)F]37), a putative tracer for the noninvasive imaging of apoptosis by positron emission tomography (PET) was synthesized by nucleophilic epoxide ring-opening of its precursor 36. The radiochemistry utilized in the (18)F-fluorination reverted to carrier-added [(18)F]Et(3)N.3HF, a new fluorine-18 source for radiolabeling.
authors.affiliation: Organisch-Chemisches Institut and International NRW Graduate School of Chemistry, Westfalische Wilhelms-Universitat, Munster, Germany.
authors.forename: Anil K
authors.initials: AK
authors.lastname: Podichetty
authors.forename: Stefan
authors.initials: S
authors.lastname: Wagner
authors.forename: Sandra
authors.initials: S
authors.lastname: Schröer
authors.forename: Andreas
authors.initials: A
authors.lastname: Faust
authors.forename: Michael
authors.initials: M
authors.lastname: Schäfers
authors.forename: Otmar
authors.initials: O
authors.lastname: Schober
authors.forename: Klaus
authors.initials: K
authors.lastname: Kopka
authors.forename: Günter
authors.initials: G
authors.lastname: Haufe
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D061945:Caspase Inhibitors; D020169:Caspases / Q000737:chemistry* / Q000378:metabolism; D005462:Fluorine Radioisotopes; D006801:Humans; D007510:Isatin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology*
chemical_list: D061945:Caspase Inhibitors; D005462:Fluorine Radioisotopes; D007510:Isatin; D020169:Caspases