title: The Nonartemisinin Sesquiterpene Lactones Parthenin and Parthenolide Block Plasmodium falciparum Sexual Stage Transmission.
abstract: Parthenin and parthenolide are natural products that are closely related in structure to artemisinin, which is also a sesquiterpene lactone (SQL) and one of the most important antimalarial drugs available. Parthenin, like artemisinin, has an effect onPlasmodiumblood stage development. We extended the evaluation of parthenin as a potential therapeutic for the transmissible stages ofPlasmodium falciparumas it transitions between human and mosquito, with the aim of gaining potential mechanistic insight into the inhibitory activity of this compound. We posited that if parthenin targets different biological pathways in the parasite, this in turn could pave the way for the development of druggable compounds that could prevent the spread of artemisinin-resistant parasites. We examined parthenin's effect on male gamete activation and the ookinete-to-oocyst transition in the mosquito as well as on stage V gametocytes that are present in peripheral blood. Parthenin arrested parasite development for each of the stages tested. The broad inhibitory properties of parthenin on the evaluated parasite stages may suggest different mechanisms of action between parthenin and artemisinin. Parthenin's cytotoxicity notwithstanding, its demonstrated activity in this study suggests that structurally related SQLs with a better safety profile deserve further exploration. We used our battery of assays to test parthenolide, which has a more compelling safety profile. Parthenolide demonstrated activity nearly identical to that of parthenin againstP. falciparum, highlighting its potential as a possible transmission-blocking drug scaffold. We discuss the context of the evidence with respect to the next steps toward expanding the current antimalarial arsenal.
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health and Malaria Research Institute, Baltimore, Maryland, USA.
authors.forename: Jared N
authors.initials: JN
authors.lastname: Balaich
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health and Malaria Research Institute, Baltimore, Maryland, USA.
authors.forename: Derrick K
authors.initials: DK
authors.lastname: Mathias
authors.affiliation: The International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
authors.forename: Baldwyn
authors.initials: B
authors.lastname: Torto
authors.affiliation: Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Jackson
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health and Malaria Research Institute, Baltimore, Maryland, USA.
authors.forename: Dingyin
authors.initials: D
authors.lastname: Tao
authors.affiliation: Department of Entomology, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Babak
authors.initials: B
authors.lastname: Ebrahimi
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health and Malaria Research Institute, Baltimore, Maryland, USA Ifakara Health Institute, Dar es Salaam, Tanzania Nelson Mandela African Institute for Science and Technology, Arusha, Tanzania.
authors.forename: Brian B
authors.initials: BB
authors.lastname: Tarimo
authors.affiliation: The International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
authors.forename: Xavier
authors.initials: X
authors.lastname: Cheseto
authors.affiliation: Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Woodbridge A
authors.initials: WA
authors.lastname: Foster
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health and Malaria Research Institute, Baltimore, Maryland, USA rdinglasan@jhu.edu.
authors.forename: Rhoel R
authors.initials: RR
authors.lastname: Dinglasan
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology; D000962:Antimalarials / Q000494:pharmacology*; D037621:Artemisinins / Q000494:pharmacology; D004351:Drug Resistance; D004912:Erythrocytes / Q000187:drug effects / Q000469:parasitology; D005260:Female; D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D008018:Life Cycle Stages / Q000187:drug effects*; D008288:Malaria / Q000469:parasitology / Q000517:prevention & control* / Q000635:transmission; D008297:Male; D051379:Mice; D010962:Plasmodium berghei / Q000187:drug effects* / Q000254:growth & development; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000254:growth & development; D012717:Sesquiterpenes / Q000494:pharmacology*
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D012717:Sesquiterpenes; D049452:Green Fluorescent Proteins; C002669:parthenolide; C022097:parthenin