title: Medicinal chemistry optimization of antiplasmodial imidazopyridazine hits from high throughput screening of a softfocus kinase library: part 2.
abstract: On the basis of our recent results on a novel series of imidazopyridazine-based antimalarials, we focused on identifying compounds with improved aqueous solubility and hERG profile while maintaining metabolic stability and in vitro potency. Toward this objective, 41 compounds were synthesized and evaluated for antiplasmodial activity against NF54 (sensitive) and K1 (multidrug resistant) strains of the malaria parasite Plasmodium falciparum and evaluated for both aqueous solubility and metabolic stability. Selected compounds were tested for in vitro hERG activity and in vivo efficacy in the P. berghei mouse model. Several compounds were identified with significantly improved aqueous solubility, good metabolic stability, and a clean hERG profile relative to a previous frontrunner lead compound. A sulfoxide-based imidazopyridazine analog 45, arising from a prodrug-like strategy, was completely curative in the Plasmodium berghei mouse model at 4 × 50 mg/kg po.
authors.affiliation: Department of Chemistry, University of Cape Town , Rondebosch 7701, South Africa.
authors.forename: Claire
authors.initials: C
authors.lastname: Le Manach
authors.forename: Tanya
authors.initials: T
authors.lastname: Paquet
authors.forename: Diego
authors.initials: D
authors.lastname: Gonzàlez Cabrera
authors.forename: Yassir
authors.initials: Y
authors.lastname: Younis
authors.forename: Dale
authors.initials: D
authors.lastname: Taylor
authors.forename: Lubbe
authors.initials: L
authors.lastname: Wiesner
authors.forename: Nina
authors.initials: N
authors.lastname: Lawrence
authors.forename: Sylva
authors.initials: S
authors.lastname: Schwager
authors.forename: David
authors.initials: D
authors.lastname: Waterson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Witty
authors.forename: Sergio
authors.initials: S
authors.lastname: Wittlin
authors.forename: Leslie J
authors.initials: LJ
authors.lastname: Street
authors.forename: Kelly
authors.initials: K
authors.lastname: Chibale
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000138:chemical synthesis* / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D051638:Ether-A-Go-Go Potassium Channels / Q000187:drug effects; D006801:Humans; D016778:Malaria, Falciparum / Q000469:parasitology; D008297:Male; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism; D021261:Parasitic Sensitivity Tests; D010962:Plasmodium berghei / Q000187:drug effects; D010963:Plasmodium falciparum / Q000187:drug effects; D011724:Pyridazines / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D012995:Solubility; D013329:Structure-Activity Relationship; D013450:Sulfones / Q000138:chemical synthesis* / Q000378:metabolism / Q000494:pharmacology
chemical_list: C000595644:6-(3-(cyclopropylsulfonyl)phenyl)-3-(4-(methylsulfinyl)phenyl)imidazo(1,2-b)pyridazine; D000962:Antimalarials; D051638:Ether-A-Go-Go Potassium Channels; D011724:Pyridazines; D013450:Sulfones