title: Synthesis of 7-benzylamino-6-chloro-2-piperazino-4-pyrrolidinopteridine and novel derivatives free of positional isomers. Potent inhibitors of cAMP-specific phosphodiesterase and of malignant tumor cell growth.
abstract: 7-Benzylamino-6-chloro-2-piperazino-4-pyrrolidinopteridine (7a) is a potent inhibitor of the cAMP-specific phosphodiesterase isoenzyme family PDE4 and induces growth inhibition in a panel of tumor cell lines. In this study, we describe a synthesis that yields 7a and novel derivatives free of positional isomers. The synthesis of alkylamino substituted pteridines is based on the successive nucleophilic aromatic substitution of the chlorine atoms of 2,4,6, 7-tetrachloropteridine. For the reaction with secondary amines, the positional order of reactivity was found to be C4 > C7 > C2 > C6. Final structural proof is given by X-ray crystallography. To unravel structural elements of 7a crucial for the interaction with the target enzyme, the compound was modified systematically. The impact of the modifications on activity was tested by evaluating the ability of the compounds to inhibit cAMP hydrolysis by cAMP-specific phosphodiesterase (PDE4) purified from the solid human large cell lung tumor xenograft LXFL529. Growth inhibitory properties were determined by in vitro treatment of the respective cell line LXFL529L using the sulforhodamine B assay (SRB). The results show that for high activity, the heterocyclic substituent in position 2 of the pteridine ring system requires the presence of a basic nitrogen in 4'-position, as represented by piperazine.
authors.affiliation: Departments of Chemistry, Division of Food Chemistry and Environmental Toxicology and Division of Inorganic Chemistry, University of Kaiserslautern, Germany.
authors.forename: K H
authors.initials: KH
authors.lastname: Merz
authors.forename: D
authors.initials: D
authors.lastname: Marko
authors.forename: T
authors.initials: T
authors.lastname: Regiert
authors.forename: G
authors.initials: G
authors.lastname: Reiss
authors.forename: W
authors.initials: W
authors.lastname: Frank
authors.forename: G
authors.initials: G
authors.lastname: Eisenbrand
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D018360:Crystallography, X-Ray; D000242:Cyclic AMP / Q000378:metabolism*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D006868:Hydrolysis; D020128:Inhibitory Concentration 50; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D008175:Lung Neoplasms / Q000201:enzymology / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D010726:Phosphodiesterase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D010879:Piperazines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011621:Pteridines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D012235:Rhodamines; D013329:Structure-Activity Relationship; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D007527:Isoenzymes; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011621:Pteridines; D012235:Rhodamines; C081896:7-benzylamino-6-chloro-2-piperazino-4-pyrrolidinopteridine; C022027:lissamine rhodamine B; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4