title: Identification of novel short chain 4-substituted indoles as potent alphavbeta3 antagonist using structure-based drug design.
abstract: The vitronectin receptor alpha(v)beta(3) has been identified as a promising potential target for the treatment of osteoporosis, diabetic retinopathy and cancer. We have recently reported 5-substituted indoles 3-[5-[2-(5,6,7,8-tetrahydro[1,8]naphthyridin-2-yl)ethoxy]indol-1-yl]-3-(3-pyridyl)propionic acid 3 and 3-[5-[2-(5,6,7,8-tetrahydro[1,8]naphthyridin-2-yl)ethoxy]indol-1-yl]-3-(3,4-methylenedioxyphenyl)propionic acid 4, as an original series of potent alpha(v)beta(3) antagonists with subnanomolar activity. Ligand-protein docking analyses have been performed to generate binding models of three different chemical classes of known alpha(v)beta(3) antagonists with alpha(v)beta(3). Results of this docking study suggested that indoles bearing the basic tetrahydronaphthyridine group at position 4 can easily adopt the correct binding conformation and should be as potent as our current 5-substituted indole leads 3 and 4. This hypothesis was nicely demonstrated by the synthesis of a series of 1,4-disubstituted indoles through a tandem of reactions involving: (i) the N-alkylation of indoles 15 and 22 with propargyl esters and cesium fluoride, and (ii) a Heck coupling reaction between 4-bromoindole and 7-vinyl-3,4-dihydro-2H-[1,8]naphthyridine-1-carboxylic acid tert-butyl ester 12, or (iii) a reductive amination involving the N-substituted-4-aminoindole 23 and the BOC-protected tetrahydro[1,8]naphthyridine aldehyde 13. Among the compounds assayed, 3-(3-pyridyl)-3-[4-[2-(5,6,7,8-tetrahydro[1,8]naphthyridin-2-yl)ethyl]indol-1-yl]propionic acid 21 showed the most promising activity on alpha(v)beta(3) (IC(50)=0.5 nM), and was found to have the same potency as our current leads 3 and 4, while maintaining selectivity over alpha(IIb)beta(IIIa). Moreover, based on the reasonable apparent permeability coefficient in an in vitro CACO-2 cell monolayer assay (P(app) apical/basolateral=2.2 x 10(-6)cm/s, P(app) basolateral/apical=2.5 x 10(-6)cm/s), compound 21 is expected to be absorbed through the intestine in human. Thus, 1,4-disubstituted indole 21 represents a new lead for this novel class of conformationally restricted alpha(v)beta(3) antagonists. Additionally, this study validates the pharmacophore model previously postulated and provides an improved basis for further structure-based drug design in the field of alpha(v)beta(3).
authors.affiliation: Drug Discovery, Johnson & Johnson Pharmaceutical Research and Development, L.L.C., 665 Stockton Drive, Exton, PA 19341, USA. pierreraboisson@aol.com
authors.forename: Pierre
authors.initials: P
authors.lastname: Raboisson
authors.forename: Renee L
authors.initials: RL
authors.lastname: Desjarlais
authors.forename: Rolanda
authors.initials: R
authors.lastname: Reed
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lattanze
authors.forename: Margery
authors.initials: M
authors.lastname: Chaikin
authors.forename: Carl L
authors.initials: CL
authors.lastname: Manthey
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Tomczuk
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Marugán
mesh_terms: D015195:Drug Design; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007202:Indicators and Reagents; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D039081:Integrin alpha5beta1 / Q000037:antagonists & inhibitors; D039302:Integrin alphaVbeta3 / Q000037:antagonists & inhibitors*; D016023:Integrins / Q000037:antagonists & inhibitors; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D040201:Platelet Membrane Glycoprotein IIb / Q000187:drug effects; D019030:Receptors, Vitronectin / Q000037:antagonists & inhibitors; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
chemical_list: D007202:Indicators and Reagents; D007211:Indoles; D039081:Integrin alpha5beta1; D039302:Integrin alphaVbeta3; D016023:Integrins; D008024:Ligands; D040201:Platelet Membrane Glycoprotein IIb; D019030:Receptors, Vitronectin; C064660:integrin alphaVbeta5