title: In vitro susceptibility of Plasmodium falciparum Welch field isolates to infusions prepared from Artemisia annua L. cultivated in the Brazilian Amazon.
abstract: Artemisinin is the active antimalarial compound obtained from the leaves of Artemisia annua L. Artemisinin, and its semi-synthetic derivatives, are the main drugs used to treat multi-drug-resistant Plasmodium falciparum (one of the human malaria parasite species). The in vitro susceptibility of P. falciparum K1 and 3d7 strains and field isolates from the state of Amazonas, Brazil, to A. annua infusions (5 g dry leaves in 1 L of boiling water) and the drug standards chloroquine, quinine and artemisinin were evaluated. The A. annua used was cultivated in three Amazon ecosystems (várzea, terra preta de índio and terra firme) and in the city of Paulínia, state of São Paulo, Brazil. Artemisinin levels in the A. annua leaves used were 0.90-1.13% (m/m). The concentration of artemisinin in the infusions was 40-46 mg/L. Field P. falciparum isolates were resistant to chloroquine and sensitive to quinine and artemisinin. The average 50% inhibition concentration values for A. annua infusions against field isolates were 0.11-0.14 μL/mL (these infusions exhibited artemisinin concentrations of 4.7-5.6 ng/mL) and were active in vitro against P. falciparum due to their artemisinin concentration. No synergistic effect was observed for artemisinin in the infusions.
authors.affiliation: Laboratório de Princípios Ativos da Amazônia, Instituto Nacional de Pesquisas da Amazônia, Manaus, AM, Brasil.
authors.forename: Luiz Francisco Rocha e
authors.initials: LF
authors.lastname: Silva
authors.forename: Pedro Melillo de
authors.initials: PM
authors.lastname: Magalhães
authors.forename: Mônica Regina Farias
authors.initials: MR
authors.lastname: Costa
authors.forename: Maria das Graças Costa
authors.initials: Md
authors.lastname: Alecrim
authors.forename: Francisco Célio Maia
authors.initials: FC
authors.lastname: Chaves
authors.forename: Ari de Freitas
authors.initials: Ade F
authors.lastname: Hidalgo
authors.forename: Adrian Martin
authors.initials: AM
authors.lastname: Pohlit
authors.forename: Pedro Paulo Ribeiro
authors.initials: PP
authors.lastname: Vieira
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D031172:Artemisia annua / Q000737:chemistry*; D037621:Artemisinins / Q000494:pharmacology; D001938:Brazil; D002738:Chloroquine / Q000494:pharmacology; D004357:Drug Synergism; D020128:Inhibitory Concentration 50; D021261:Parasitic Sensitivity Tests / Q000379:methods; D010936:Plant Extracts / Q000494:pharmacology*; D010963:Plasmodium falciparum / Q000187:drug effects*; D011803:Quinine / Q000494:pharmacology
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D010936:Plant Extracts; D002738:Chloroquine; C031327:artemisinin; D011803:Quinine