Macrocyclic Pyrrolizidine Alkaloids from Crotalaria rosenii

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Addis Ababa Universty


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.



Crotolaria rosenii