Patterns of pyrrolizidine alkaloids in 12 Ethiopian Crotalaria species

Thirty-three alkaloidal extracts prepared from different parts of 12 Ethiopian Crotalaria species have been analysed for their alkaloid profiles using GLC-MS. Eleven of the species investigated namely, C. agatiflora Schweinf. subsp. erlangeri Bak. f., C albicaulis Franch., C axillaris Ait., C emarginella Vatke, C fascicularis Polhill, C gillettii Polhill, C incana L. subsp. purpurascens (Lam.) Milne-Redh., C laburnifolia L. subsp. tenuicarpa Polhill, C mildabraedi Bak. f., C phillipsiae Bak. and C pycnostachya Benth. contain pyrrolizidine alkaloids (PAs). No pyrrolizidine alkaloid could be detected in C spinosa Hochst. ex Benth. Alkaloid contents ranged between 0.02%, dry weight (for the twigs of C pycnostachya) and 2.88% (for the seeds of C axillaris). The alkaloidal patterns of the various organs of the plants have been determined by capillary GLC and GLC-MS. In addition to the commonly found PAs (simple esters and macrocyclic diesters), C. laburnifolia subsp. tenuicarpa and C. phillipsiae were shown to be adept in the biosynthetic elaboration of seco-pyrrolizidine alkaloids. The simple indolizidine alkaloid tashiromine, figured as a major compound in C. emarginella, C. phillipsiae and C spinosa. It was also detected as a minor component of C fascicularis. Altogether 37 alkaloids have been identified by GLC MS. Most of these alkaloids were detected in the respective plants for the first time. Prior to our work, some of the alkaloids were not reported in the genus Crotalaria. The majority of the alkaloids identified were the potentially toxic macrocyclic diesters with a double bond at 1:2 position. (C) 2004 Elsevier Ltd. All rights reserved.