title: Potent Plasmodium falciparum gametocytocidal activity of diaminonaphthoquinones, lead antimalarial chemotypes identified in an antimalarial compound screen.
abstract: Forty percent of the world's population is threatened by malaria, which is caused by Plasmodium parasites and results in an estimated 200 million clinical cases and 650,000 deaths each year. Drug resistance has been reported for all commonly used antimalarials and has prompted screens to identify new drug candidates. However, many of these new candidates have not been evaluated against the parasite stage responsible for transmission, gametocytes. If Plasmodium falciparum gametocytes are not eliminated, patients continue to spread malaria for weeks after asexual parasite clearance. Asymptomatic individuals can also harbor gametocyte burdens sufficient for transmission, and a safe, effective gametocytocidal agent could also be used in community-wide malaria control programs. Here, we identify 15 small molecules with nanomolar activity against late-stage gametocytes. Fourteen are diaminonaphthoquinones (DANQs), and one is a 2-imino-benzo[d]imidazole (IBI). One of the DANQs identified, SJ000030570, is a lead antimalarial candidate. In contrast, 94% of the 650 compounds tested are inactive against late-stage gametocytes. Consistent with the ineffectiveness of most approved antimalarials against gametocytes, of the 19 novel compounds with activity against known anti-asexual-stage targets, only 3 had any strong effect on gametocyte viability. These data demonstrate the distinct biology of the transmission stages and emphasize the importance of screening for gametocytocidal activity. The potent gametocytocidal activity of DANQ and IBI coupled with their efficacy against asexual parasites provides leads for the development of antimalarials with the potential to prevent both the symptoms and the spread of malaria.
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA.
authors.forename: Takeshi Q
authors.initials: TQ
authors.lastname: Tanaka
authors.affiliation: Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: W Armand
authors.initials: WA
authors.lastname: Guiguemde
authors.affiliation: Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Barnett
authors.affiliation: Department of Biology, Loyola University Chicago, Chicago, Illinois, USA.
authors.forename: Maxim I
authors.initials: MI
authors.lastname: Maron
authors.affiliation: Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Jaeki
authors.initials: J
authors.lastname: Min
authors.affiliation: Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Michele C
authors.initials: MC
authors.lastname: Connelly
authors.affiliation: Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Praveen Kumar
authors.initials: PK
authors.lastname: Suryadevara
authors.affiliation: Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: R Kiplin
authors.initials: RK
authors.lastname: Guy
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, USA Department of Biology, Loyola University Chicago, Chicago, Illinois, USA kwilli4@luc.edu.
authors.forename: Kim C
authors.initials: KC
authors.lastname: Williamson
mesh_terms: D000962:Antimalarials / Q000737:chemistry / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical; D056945:Hep G2 Cells; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D009285:Naphthoquinones / Q000737:chemistry / Q000494:pharmacology*; D010963:Plasmodium falciparum / Q000187:drug effects*; D013329:Structure-Activity Relationship
chemical_list: D000962:Antimalarials; D007093:Imidazoles; D009285:Naphthoquinones