title: Design, synthesis, and evaluation of 6-carboxyalkyl and 6-phosphonoxyalkyl derivatives of 7-oxo-8-ribitylaminolumazines as inhibitors of riboflavin synthase and lumazine synthase.
abstract: A series of 6-carboxyalkyl and 6-phosphonoxyalkyl derivatives of 7-oxo-8-D-ribityllumazine were synthesized as inhibitors of both Escherichia coli riboflavin synthase and Bacillus subtilis lumazine synthase. The compounds were designed to bind to both the ribitylpurine binding site and the phosphate binding site of lumazine synthase. In the carboxyalkyl series, maximum activity against both enzymes was observed with the 3'-carboxypropyl compound 22. Lengthening or shortening the chain linking the carboxyl group to the lumazine by one carbon resulted in decreased activity. In the phosphonoxyalkyl series, the 3'-phosphonoxypropyl compound 33 was more potent than the 4'-phosphonoxybutyl derivative 39 against lumazine synthase, but it was less potent against riboflavin synthase. Molecular modeling suggested that the terminal carboxyl group of 6-(3'-carboxypropyl)-7-oxo-8-D-ribityllumazine (22) may bind to the side chains of Arg127 and Lys135 of the enzyme. A hypothetical molecular model was also constructed for the binding of 6-(2'-carboxyethyl)-7-oxolumazine (15) in the active site of E. coli riboflavin synthase, which demonstrated that the active site could readily accommodate two molecules of the inhibitor.
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, Indiana 47907, USA. cushman@pharmacy.purdue.edu
authors.forename: Mark
authors.initials: M
authors.lastname: Cushman
authors.forename: Donglai
authors.initials: D
authors.lastname: Yang
authors.forename: Stefan
authors.initials: S
authors.lastname: Gerhardt
authors.forename: Robert
authors.initials: R
authors.lastname: Huber
authors.forename: Markus
authors.initials: M
authors.lastname: Fischer
authors.forename: Klaus
authors.initials: K
authors.lastname: Kis
authors.forename: Adelbert
authors.initials: A
authors.lastname: Bacher
mesh_terms: D001665:Binding Sites; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011487:Protein Conformation; D011621:Pteridines / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D012255:Ribitol / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D012258:Riboflavin Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D009097:Multienzyme Complexes; D011621:Pteridines; C008297:lumazine; D012255:Ribitol; C044822:6,7-dimethyl-8-ribityllumazine synthase; D012258:Riboflavin Synthase