Antiparasitic activities and toxicities of individual enantiomers of the 8-aminoquinoline 8-[(4-amino-1-methylbutyl)amino]-6-methoxy-4-methyl-5-[3,4-dichlorophenoxy]quinoline succinate.
8-Aminoquinolines are an important class of antiparasitic agents, with broad utility and excellent efficacy, but also limitations due to hematological toxicities, primarily methemoglobinemia and hemolysis. One representative from this class, (+/-)-8-[(4-amino-1-methylbutyl)amino]-6-methoxy-4-methyl-5-[3,4-dichlorophenoxy]quinoline succinate (NPC1161C), proved extremely efficacious in animal models of malaria and pneumocystis pneumonia. This racemic mixture was separated into its component enantiomers by chemical and chromatographic means. The enantiomers were evaluated for antiparasitic activity in murine models of Plasmodium berghei, Pneumocystis carinii, and Leishmania donovani infection, as well as the propensity to elicit hematotoxicity in dogs. The (-)-enantiomer NPC1161B was found to be more active (by severalfold, depending on the dosing regimen) than the (+)-enantiomer NPC1161A in all of these murine models. In addition, the (-) enantiomer showed markedly reduced general toxicity in mice and reduced hematotoxicity in the dog model of methemoglobinemia. It is concluded that the configuration at the asymmetric center in the 8-amino side chain differentially affects efficacy and toxicity profiles and thus may be an important determinant of the "therapeutic window" for compounds in this class.
Nanayakkara
N P Dhammika
NP
National Center for Natural Products Research, School of Pharmacy, University of Mississippi, University, MS 38677, USA. dhammika@olemiss.edu
Ager
Arba L
AL
Bartlett
Marilyn S
MS
Yardley
Vanessa
V
Croft
Simon L
SL
Khan
Ikhlas A
IA
McChesney
James D
JD
Walker
Larry A
LA
D000634:Aminoquinolines / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use / Q000633:toxicity; D000818:Animals; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D000981:Antiprotozoal Agents / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D004285:Dogs; D005260:Female; D006461:Hemolysis; D006801:Humans; D007893:Leishmania donovani / Q000187:drug effects*; D007898:Leishmaniasis, Visceral / Q000188:drug therapy / Q000469:parasitology; D008288:Malaria / Q000188:drug therapy / Q000469:parasitology; D008297:Male; D008708:Methemoglobinemia / Q000209:etiology; D051379:Mice; D008807:Mice, Inbred BALB C; D010962:Plasmodium berghei / Q000187:drug effects*; D045363:Pneumocystis carinii / Q000187:drug effects*; D011020:Pneumonia, Pneumocystis / Q000188:drug therapy / Q000382:microbiology; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D000634:Aminoquinolines; D000935:Antifungal Agents; D000981:Antiprotozoal Agents; C080436:8-aminoquinoline