Macrocyclic Pyrrolizidine Alkaloids from Crotalaria rosenii
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Date
1986-06
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Addis Ababa Universty
Abstract
Crotolaria rosenii, family Leguminosae, is a poisonous
endemic shrub or small slender tree found in
Iaountain scrub and forest clearings between 2000 and 3000
m. The powderod leves and flowers of C. rosenii were
defatted with petroleum ether (60-800 C), extracted \'lith
r~ethanol (soxhlet) and subjected to acid-base extraction
to give a raw basic extract containing nine alkaloids.
Column chromatogr2.phic separn.tion of the raw extract on
silica gel with chloroform-methanol mixture resulted in
the isolation of three alkaloids. The structures of
these alkaloids were determined by 2-dimensional nuclear
wagnetic resonanco techniques as well as mass and infrared
spectra. The three alkaloids were identified as madurensinG,
7-acetyl maclurensine and Crotaflorine.
11pplication of homo and hetero nucleHl.' shift correlations
have enabled unequivocal assignments of the carbon
chemical shifts of these compounds and pointed out erraneous
conclusion made by other workers.
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Keywords
Crotolaria rosenii