title: Antiplasmodial quinones from the rhizomes of Kniphofia foliosa.
abstract: Extracts of the rhizomes of Kniphofia foliosa exhibited antiplasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC50 values of 3-5 microg/mL. A phenyloxanthrone, named 10-acetonylknipholone cyclooxanthrone (1) and an anthraquinone-anthrone dimer, chryslandicin 10-methyl ether (2), were isolated from the rhizomes, along with known quinones, including the rare phenylanthraquinone dimers, joziknipholones A and B. The structures of these compounds were determined based on spectroscopic data. This is the second report on the occurrence of the dimeric phenylanthraquinones in nature. In an in vitro antiplasmodial assay of the isolated compounds, activity was observed for phenylanthraquinones, anthraquinone-anthrone dimers and dimeric phenylanthraquinones, with joziknipholone A being the most active. The new compound, 10-acetonylknipholone cyclooxanthrone, also showed anti-plasmodial activity. In an in vivo assay, knipholone anthrone displayed marginal antimalarial activity.
authors.affiliation: Department of Chemistry, University of Nairobi, P.O. Box 30197-00100, Nairobi, Kenya.
authors.forename: Martha
authors.initials: M
authors.lastname: Induli
authors.forename: Meron
authors.initials: M
authors.lastname: Gebru
authors.forename: Negera
authors.initials: N
authors.lastname: Abdissa
authors.forename: Hosea
authors.initials: H
authors.lastname: Akala
authors.forename: Ingrid
authors.initials: I
authors.lastname: Wekesa
authors.forename: Robert
authors.initials: R
authors.lastname: Byamukama
authors.forename: Matthias
authors.initials: M
authors.lastname: Heydenreich
authors.forename: Sylvia
authors.initials: S
authors.lastname: Murunga
authors.forename: Ermias
authors.initials: E
authors.lastname: Dagne
authors.forename: Abiy
authors.initials: A
authors.lastname: Yenesew
mesh_terms: D000962:Antimalarials / Q000737:chemistry / Q000302:isolation & purification*; D019668:Liliaceae / Q000737:chemistry*; D015394:Molecular Structure; D021261:Parasitic Sensitivity Tests; D011809:Quinones / Q000737:chemistry / Q000302:isolation & purification*; D027343:Rhizome / Q000737:chemistry
chemical_list: D000962:Antimalarials; D011809:Quinones