In vitro antiplasmodial activity of 4-phenylcoumarins from Exostema mexicanum.
The stem bark of Exostema mexicanum (Rubiaceae) is used in Latin American folk medicine as a quinine substitute for malaria treatment. Bioassay-guided fractionation of lipophilic and hydrophilic extracts from the stem bark and branches yielded two previously undescribed 4-phenylcoumarins: 4',8-dihydroxy-5,7-dimethoxy-4-phenylcoumarin (exomexin A) and 3',4'-dihydroxy-5,7,8-trimethoxy-4-phenylcoumarin (exomexin B). Together with five known derivatives the in vitro activities against a chloroquine-sensitive strain (poW) and a chloroquine-resistant strain (Dd2) of Plasmodium falciparum have been evaluated. The most lipophilic compound, 4',5,7,8-tetramethoxy-4-phenylcoumarin (O-methylexostemin) revealed the strongest antiplasmodial activity (IC50 values: 3.6 microg/ml [poW], 1.6 microg/ml [Dd2]).
I
I
Köhler
K
K
Jenett-Siems
F P
FP
Mockenhaupt
K
K
Siems
J
J
Jakupovic
J C
JC
González
M A
MA
Hernández
R A
RA
Ibarra
W G
WG
Berendsohn
U
U
Bienzle
E
E
Eich
D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D003374:Coumarins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D019684:Magnoliopsida / Q000737:chemistry*; D013058:Mass Spectrometry; D015394:Molecular Structure; D010963:Plasmodium falciparum / Q000187:drug effects*; D019666:Rubiaceae / Q000737:chemistry*
D000962:Antimalarials; D003374:Coumarins; C094411:4-phenylcoumarin