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The first 60-O-sulfated phenylanthraquinones: isolation from Bulbine frutescens, structural elucidation, enantiomeric purity, and partial synthesis

Mutanyatta, J.; Bezabih, M.; Abegaz, B.; Dreyer, M.; Brun, R.; Kocher, N.; Bringmann, G (Elsevier Ltd.http://www.elsevier.com/wps/find/journaldescription.cws_home/942/description#description, NaN, 2005)

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Abstract:

From the roots of Bulbine frutescens, the first sulfated phenylanthraquinones were isolated, together with their known sulfate-free analogs. Their structures were elucidated by spectroscopic and chiroptical methods, by acid hydrolysis or by partial synthesis. The new compounds have the usual stereo-orientation at the biaryl axis (i.e., with the acetyl portion above the anthraquinone plane) except for sodium ent-knipholone 60-O-sulfate (and thus, also its hydrolysis product, ent-knipholone), which exhibit an opposite axial configuration. We also describe the first stereoanalysis of natural phenylanthraquinones, some of which were found to be not enantiomerically pure, some even nearracemic. We furthermore, report on the first X-ray structure analysis of a phenylanthraquinone, viz. 40-O-demethylknipholone.

URI:

http://hdl.handle.net/10311/246

Files in this item: 2

license.txt (1.998Kb)

The first 6-0-O-sulfated phenylanthraquinones.pdf (6.446Mb)

Gaboroquinones A and B and 4'-O-demethylknipholone-4'-O-β-D-glucopyranoside, phenylanthraquinones from the roots of Bulbine frutescens

Abegaz, B.M.; Bezabih, M.; Msuta, T.; Brun, R.; Menche, D.; Muhlbacher, J.; Bringmann, G. (American Chemical Society. http://pubs.acs.org/jnp/, NaN, 2002)

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Abstract:

The novel phenylanthraquinones 4'-O-demethylknipholone-4'-O-β-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.

URI:

http://hdl.handle.net/10311/346

Files in this item: 1

Gaboroquinones.pdf (407.3Kb)

Now showing items 1-2 of 2

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