title: Lead discovery of inhibitors of the dihydrofolate reductase domain of Plasmodium falciparum dihydrofolate reductase-thymidylate synthase.
abstract: A three-dimensional structure model of the dihydrofolate reductase (DHFR) domain of the bifunctional DHFR-thymidylate synthase of Plasmodium falciparum was used as a basis for computational screening of commercially available compounds for candidate inhibitors. Compounds which can stably dock to the model with strong ionic hydrogen bonds via protonation by an aspartic acid residue at the bottom of the active site were identified through docking simulation. Among compounds thus identified, 21 were assayed for inhibitory activity towards the recombinant DHFR domain. Two compounds, 2-amino-1,4-dihydro-4,4,7,8-tetramethyl-s-triazino(1,2-a)benzimida zole and Trp-P-2, inhibited the recombinant P. falciparum DHFR domain with Ki values of 0.54 and 8.7 microM, respectively. Kinetic analysis showed that these compounds competitively inhibited the enzyme with respect to the substrate dihydrofolate. These findings support the validity of both the modeled structure and the docking results. Furthermore, these compounds serve as leads for developing new DHFR inhibitors, since their skeletal structures are different from any of known DHFR inhibitors. This paper also reveals a new biological activity of Trp-P-2, a potent mutagen.
authors.affiliation: Faculty of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Toyoda
authors.forename: R K
authors.initials: RK
authors.lastname: Brobey
authors.forename: G
authors.initials: G
authors.lastname: Sano
authors.forename: T
authors.initials: T
authors.lastname: Horii
authors.forename: N
authors.initials: N
authors.lastname: Tomioka
authors.forename: A
authors.initials: A
authors.lastname: Itai
mesh_terms: D000818:Animals; D001562:Benzimidazoles / Q000737:chemistry* / Q000494:pharmacology; D001665:Binding Sites; D002243:Carbolines / Q000737:chemistry* / Q000494:pharmacology; D002645:Chickens; D005493:Folic Acid Antagonists / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D006860:Hydrogen Bonding; D007700:Kinetics; D007780:Lacticaseibacillus casei / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D009153:Mutagens / Q000737:chemistry; D010963:Plasmodium falciparum / Q000201:enzymology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*
chemical_list: C106798:2-amino-1,4-dihydro-4,4,7,8-tetramethyl-s-triazino(1,2-a)benzimidazole; D001562:Benzimidazoles; D002243:Carbolines; D005493:Folic Acid Antagonists; D009097:Multienzyme Complexes; D009153:Mutagens; D011994:Recombinant Proteins; C056930:thymidylate synthase-dihydrofolate reductase; C019133:3-amino-1-methyl-5H-pyrido(4,3-b)indole; D013762:Tetrahydrofolate Dehydrogenase; D013940:Thymidylate Synthase