CHEMOTAXONOMIC VALUE OF STEROLS AND STEROIDAL SAPOGENINS IN THE GENUSTRIGONELLA

The composition in sterols and steroidal sapogenins was investigated i n seven species of the genus Trigonella. Fenugreek (Trigonella foenum- graecom L.), considered as representative of this genus, was used as a reference species. Its sterolic composition is characterized by a qua si absence of stigmasterol and by the presence of Delta 7-sterols and of pollinastanol (14 alpha-methyl-9 beta,19-cyclo-5 alpha-cholestan-3 beta-ol), an unusual sterol. The composition in steroidal sapogenins ( 11 different compounds representing 1.5% DW) is also taken into consid eration. The results of the analysis of these substances in the seven species studied are presented and their taxonomic contribution is disc ussed. First, our results support the unchanged assignment of T. corni culata (L.) L., T. caerulea (L.) Ser. and T. melilotus caeruleus (L.) Ascherson et Graebner to the genus Trigonella. They confirm the regrou p of the two last species under the name of T. caerulea (L.) Ser. The transfer of T. monspeliaca L. to the genus Medicago is also confirmed, this species presenting a sterolic composition different from the oth er species but similar to that of Medicago sativa L. However, our resu lts do not support completely the unchanged assignment of T. cellicera s Fisch. in M. Bieb. to the genus Trigonella, nor the reassignment of T. cretica (L.) Boiss. to Melilotus cretica (L.) Desr., the compositio n of this species being close to that of Trigonella foenum-graecum L. for the compounds investigated. In conclusion, we propose the use of p ollinastanol and steroidal sapogenins as chemotaxonomic markers to inv estigate the generic separation between Trigonella, Medicago and Melil otus. Copyright (C) 1996 Elsevier Science Ltd