Publications

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2012
N. MM. "Antiplasmodial Quinones from Pentas longiflora and Pentas lanceolata." Planta medica. 2012; 78 :31-35. Abstract

The dichloromethane/methanol (1:1) extracts of the roots of Pentas longiflora and Pentas lanceolata showed low micromolar (IC(50) = 0.9-3 µg/mL) IN VITRO antiplasmodial activity against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of PLASMODIUM FALCIPARUM. Chromatographic separation of the extract of PENTAS LONGIFLORA led to the isolation of the pyranonaphthoquinones pentalongin (1) and psychorubrin (2) with IC(50) values below 1 µg/mL and the naphthalene derivative mollugin (3), which showed marginal activity. Similar treatment of Pentas lanceolata led to the isolation of eight anthraquinones ( 4-11, IC(50) = 5-31 µg/mL) of which one is new (5,6-dihydroxydamnacanthol, 11), while three--nordamnacanthal (7), lucidin-ω-methyl ether (9), and damnacanthol (10)--are reported here for the first time from the genus Pentas. The compounds were identified by NMR and mass spectroscopic techniques.

2011
Mbogua M. "Antiplasmodial Quinones from Pentas longiflora and Pentas lanceolata.". 2011. AbstractFull Text Link

The dichloromethane/methanol (1 : 1) extracts of
the roots of Pentas longiflora and Pentas lanceolata
showed low micromolar (IC50 = 0.9–3 µg/mL) in
vitro antiplasmodial activity against chloroquineresistant
(W2) and chloroquine-sensitive (D6)
strains of Plasmodium falciparum. Chromatographic
separation of the extract of Pentas longiflora
led to the isolation of the pyranonaphthoquinones
pentalongin (1) and psychorubrin (2)
with IC50 values below 1 µg/mL and the naphthalene
derivative mollugin (3), which showed marginal
activity. Similar treatment of Pentas lanceolata
led to the isolation of eight anthraquinones
(4–11, IC50 = 5–31 µg/mL) of which one is new
(5,6-dihydroxydamnacanthol, 11), while three –
nordamnacanthal (7), lucidin-ω-methyl ether (9),
and damnacanthol (10) – are reported here for
the first time from the genus Pentas. The compounds
were identified by NMR and mass spectroscopic
techniques.

2009
M.N. M. "8-METHOXYNEORAUTENOL AND RADICAL SCAVENGING FLAVONOIDS FROM ERYTHRINA ABYSSINICA." Bulletin of the Chemical Society of Ethiopia. 2009;23(2):205-210. Abstract

A new pterocarpan (named 8-methoxyneorautenol) was isolated from the acetone extract of the
root bark of Erythrina abyssinica. In addition, the known isoflavonoid derivatives eryvarin L, erycristagallin and
shinpterocarpin were identified for the first time from the roots of this plant. The structures were determined on
the basis of spectroscopic evidence. The new compound showed selective antimicrobial activity against
Trichophyton mentagrophytes. The acetone extract of the root bark of E. abyssinica showed radical scavenging
activity towards 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The pterocarpenes, 3-hydroxy-9-methoxy-10-(3,3-
dimethylallyl)pterocarpene and erycristagallin, were the most active constituents of the roots of this plant and showing dose-dependent activities similar to that of the standard quercetin.

2007
"CONVERSION OF VERNONIA GALAMENSIS OIL TO PYRIDINO-VERNOLAMIDES AND THEIR ANTIMICROBIAL ACTIVITIES." Bull. Chem. Soc. Ethiop. . 2007;21(1):1-8. Abstract

Vernonia oil extracted by Soxhlet extraction from the seeds of Vernonia galamensis
ssp. nairobensis was reacted with 2-aminopyridine, 2-(aminomethyl)pyridine and 2-
(aminoethyl)pyridine using a 1:3 mole ratio of vernonia oil to amine at varied temperatures to give
the corresponding vernolamides. The expected vernolamide from the reaction of 2-aminopyridine
and the oil was not formed. N-(2-pyridinylmethyl)vernolamide and N-(2-
pyridinylethyl)vernolamide exhibited antibacterial activity that was shown to be higher against
gram-positive (Bacillus subtilis) than gram-negative (Escherichia coli) bacteria. The vernolamides
did not show any antifungal activity.

2006
Mbugua MN. "Synthesis of aminoalkyl vernolamides from vernonia oil at varied conditions." Journal of Kenya Chemical Society. 2006;3(1):1-8. Abstract

The oil extracted from the seeds of Vernonia galamensis ssp. nairobensis was reacted with 1,6-diaminohexane and 1,8-diaminooctane using a 1:3 molar ratio of vernonia oil to amine to give the corresponding vernolamides. Varied temperatures and solvents were applied. The vernolamides exhibited antibacterial activity against gram-positive (Bacillus subtilis) and on gram-negative (Escherichia coli) bacteria. The vernolamides did not show any antifungal activity.

2001
Extraction of vernonia oil from vernonia galamensis seeds and its aminolysis to vernolamides.; 2001. Abstract

Vernonia galamensis grows as a common weed and is widely distributed in Africa,
and its center of diversity is found in East Africa. The dry seeds of Vernonia galamensis
contains a naturally epoxidized oil that is rich in trivernolin, which constitutes about 80% of
the seeds oil. The vernonia oil has a unique structure that makes it attractive for the
preparation of novel and useful products.
This study reports on the extraction of vernonia oil and its conversion to vernolamides
with higher added value. The oil was extracted from the seeds of Vernonia galamensis ssp.
nairobensis using soxhlet extraction. About 31.6% of crude oil was obtained which after
refining gave about 25.2% of oil. The oil was then reacted with 1,6-diaminohexane, 1,8-
diaminooctane, 2-aminopyridine, 2-(aminomethyl)pyridine and 2-(2-aminoethyl)pyridine to
give the corresponding vernolamides under two varied conditions, temperature (25,70 and
80°C) and solvents (neat, chloroform, dichloromethane and dimethylformamide). In all
~
reactions a mole ratio of vernonia oil to amine (1 :3) was used at the reaction time of 12 h.
!
In all cases, highest yields of the vernolamides (4l.2-72.3%) were obtained at 70°C in
chloroform, while the lowest yields (21-53.3%) were recorded at 80°C. The reactions at 25°C
gave reasonably high yields (17-62.8%), thus aminolysis proceeds even at room temperature.
Aminolysis carried under neat conditions also gave relatively high yields (41-64.2%).
The vernolamides were analyzed by thin-layer chromatography (TLC), infrared (IR),
electron impact mass spe~ctroscopy (ElMS) and nuclear magnetic resonance (NMR)
spectroscopic techniques.
The antimicrobial activities of the products were investigated at concentrations of
~
100)..lg, 50)..lg and 25)..lg by the disc diffusion method. The vernolamides exhibited only
antibacterial activity and was greater against gram-positive (Bacillus subtilis) than in gramIX
negative (Escherichia coli) bacteria. There was no antifungal activity shown on all the fungi
that were investigated.

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