TY  - JOUR
A1  - Abdissa, Negera
A1  - Heydenreich, Matthias
A1  - Midiwo, Jacob O.
A1  - Ndakala, Albert
A1  - Majer, Zsuzsanna
A1  - Neumann, Beate
A1  - Stammler, Hans-Georg
A1  - Sewald, Norbert
A1  - Yenesew, Abiy
T1  - A xanthone and a phenylanthraquinone from the roots of Bulbine frutescens, and the revision of six seco-anthraquinones into xanthones
JF  - Phytochemistry letters
N2  - Phytochemical investigation of the dichloromethane/methanol (1:1) extract of the roots of Bulbine frutescens led to the isolation of a new xanthone, 8-hydroxy-6-methylxanthone-1-carboxylic acid (1) and a new phenylanthraquinone, 6',8-O-dimethylknipholone (2) along with six known compounds. The structures were elucidated on the basis of NMR and MS spectral data analyses. The structure of compound 1 was confirmed through X-ray crystallography which was then used as a reference to propose the revision of the structures of six seco-anthraquinones into xanthones. The isolated compounds were evaluated for cytotoxicity against human cervix carcinoma KB-3-1 cells with the phenylanthraquinone knipholone being the most active (IC50 = 0.43 mu M). Two semi-synthetic knipholone derivatives, knipholone Mannich base and knipholone-1,3-oxazine, were prepared and tested for cytotoxic activity; both showed moderate activities (IC50 value of 1.89 and 2.50 mu M, respectively). (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
KW  - Bulbine frutescens
KW  - Xanthone
KW  - seco-Anthraquinone
KW  - Phenylanthraquinone
KW  - Cytotoxicity
KW  - Structure revision
Y1  - 2014
U6  - https://doi.org/10.1016/j.phytol.2014.04.004
SN  - 1874-3900
SN  - 1876-7486
VL  - 9
SP  - 67
EP  - 73
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Atilaw, Yoseph
A1  - Heydenreich, Matthias
A1  - Ndakala, Albert
A1  - Akala, Hoseah M.
A1  - Kamau, Edwin
A1  - Yenesew, Abiy
T1  - 3-Oxo-14 alpha, 15 alpha-epoxyschizozygine: A new schizozygane indoline alkaloid from Schizozygia coffaeoides
JF  - Phytochemistry letters
N2  - The stem bark extract of Schizozygia coffaeoides (Apocynaceae) showed moderate antiplasmodial activity (IC50 = 8-12 mu g/mL) against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the extract led to the isolation of a new schizozygane indoline alkaloid, named 3-oxo-14 alpha, 15 alpha-epoxyschizozygine. In addition, two dimeric anthraquinones, cassiamin A and cassiamin B, were identified for the first time in the family Apocynaceae. The structures of the isolated compounds were deduced on the basis of spectroscopic evidence. The schizozygane indole alkaloids showed good to moderate antiplasmodial activities (IC50 = 13-52 mu m). (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
KW  - Schizozygia coffaeoides
KW  - Schizozygane indoline alkaloid
KW  - 3-Oxo-14 alpha, 15 alpha-epoxyschizozygine
KW  - Dimeric anthraquinone
KW  - Cassiamin A
KW  - Cassiamin B
Y1  - 2014
U6  - https://doi.org/10.1016/j.phytol.2014.07.003
SN  - 1874-3900
SN  - 1876-7486
VL  - 10
SP  - 28
EP  - 31
PB  - Elsevier
CY  - Amsterdam
ER  -