Gaboroquinones A and B and 4'-O-demethylknipholone-4'-O-beta-D-glucopyranoside, phenylanthraquinones from the roots of Bulbine frutescens.
The novel phenylanthraquinones 4'-O-demethylknipholone-4'-O-beta-D-glucopyranoside (2) and gaboroquinones A (3) and B (4) were isolated from the African medicinal plant Bulbine frutescens. Biaryl 2 represents the first phenylanthraquinone glucoside, while 3 and 4 are the first side-chain-hydroxylated phenylanthraquinones. Their constitutions were determined by spectroscopic analysis, in particular by HMBC, HMQC, and ROESY NMR investigations, and by chemical transformations. The axial configurations were elucidated chemically, by deglucosylation of 2 and by side-chain deoxygenation of 3 and 4 to give the known phenylanthraquinones 4'-O-demethylknipholone (5), isoknipholone (6), and knipholone (1), respectively, and chiroptically, by CD investigations. Compounds 2, 3, and 4 showed moderate to good antiplasmodial and antitrypanosomal activities in vitro.
Department of Chemistry, University of Botswana, Private Bag 0022, Gaborone, Botswana.
Berhanu M
BM
Abegaz
Merhatibeb
M
Bezabih
Thomas
T
Msuta
Reto
R
Brun
Dirk
D
Menche
Jörg
J
Mühlbacher
Gerhard
G
Bringmann
D000818:Animals; D000880:Anthraquinones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D000962:Antimalarials / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001902:Botswana; D002942:Circular Dichroism; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D018517:Plant Roots / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D010963:Plasmodium falciparum / Q000187:drug effects; D014344:Trypanocidal Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D014345:Trypanosoma / Q000187:drug effects
C466223:4'-O-demethylknipholone-4'-O-glucopyranoside; D000880:Anthraquinones; D000962:Antimalarials; D005960:Glucosides; D014344:Trypanocidal Agents; C466224:gaboroquinone A; C466225:gaboroquinone B; C403586:knipholone