title: Joziknipholones A and B: the first dimeric phenylanthraquinones, from the roots of Bulbine frutescens.
abstract: From the roots of the African plant Bulbine frutescens (Asphodelaceae), two unprecedented novel dimeric phenylanthraquinones, named joziknipholones A and B, possessing axial and centrochirality, were isolated, together with six known compounds. Structural elucidation of the new metabolites was achieved by spectroscopic and chiroptical methods, by reductive cleavage of the central bond between the monomeric phenylanthraquinone and -anthrone portions with sodium dithionite, and by quantum chemical CD calculations. Based on the recently revised absolute axial configuration of the parent phenylanthraquinones, knipholone and knipholone anthrone, the new dimers were attributed to possess the P-configuration (i.e., with the acetyl portions below the anthraquinone plane) at both axes in the case of joziknipholone A, whereas in joziknipholone B, the knipholone part was found to be M-configured. Joziknipholones A and B are active against the chloroquine resistant strain K1 of the malaria pathogen, Plasmodium falciparum, and show moderate activity against murine leukemic lymphoma L5178y cells.
authors: Institut für Organische Chemie, Universität Würzburg, Am Hubland, Würzburg, Germany. bringman@chemie.uni-wuerzburg.de
authors: Gerhard
authors: G
authors: Bringmann
authors: Joan
authors: J
authors: Mutanyatta-Comar
authors: Katja
authors: K
authors: Maksimenka
authors: John M
authors: JM
authors: Wanjohi
authors: Matthias
authors: M
authors: Heydenreich
authors: Reto
authors: R
authors: Brun
authors: Werner E G
authors: WE
authors: Müller
authors: Martin G
authors: MG
authors: Peter
authors: Jacob O
authors: JO
authors: Midiwo
authors: Abiy
authors: A
authors: Yenesew
mesh_terms: D000465:Algorithms; D000818:Animals; D000880:Anthraquinones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000962:Antimalarials / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D045744:Cell Line, Tumor / Q000187:drug effects; D002738:Chloroquine / Q000494:pharmacology; D019281:Dimerization; D004227:Dithionite / Q000737:chemistry; D004351:Drug Resistance; D007940:Leukemia L5178; D019668:Liliaceae / Q000737:chemistry*; D051379:Mice; D015394:Molecular Structure; D018517:Plant Roots / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D010963:Plasmodium falciparum / Q000187:drug effects*; D011789:Quantum Theory; D051381:Rats; D013057:Spectrum Analysis; D013237:Stereoisomerism
chemical_list: D000880:Anthraquinones; D000962:Antimalarials; D000972:Antineoplastic Agents, Phytogenic; C528553:joziknipholone A; C528554:joziknipholone B; D004227:Dithionite; D002738:Chloroquine