Abstract
In a chemotaxonomic study of the genus Thapsia (Apiaceae), root material of five taxa has been analysed for skin irritating sesquiterpene
lactones and the coumarins, 6-methoxy-7-geranyloxycoumarin and scopoletin. Eight tetraesters
of 2, 3, 7, 8, 10, 11-hexahydroxy-C6-guaianolide and two triesters of 3, 7, 8, 10, 11-pentahydroxy-C6-guaianolide were isolated. One of these, trilobolide, has previously been isolated
from Laser trilobum BORKH., whereas the others are new. They represent a new group of selective histamine liberators.
Regarding the investigated constituents, T. garganica L. was found to differ from T. transtagana BROT. T. villosa L. proved to be chemically heterogeneous and the examined plant samples could be
divided into four chemical groups, named I-IV. Hydroxylated C6-guaianolides were isolated from T. garganica, T. transtagana, T. maxima MILL., T. villosa I and III. No skin irritating guaianolides were detected in either T. villosa II and IV or in Rouya (Thapsia) polygama (DESF.) COINCY. 6-Methoxy-7-geranyloxycoumarin showed the same distribution as the guaianolides,
whereas scopoletin was found in all the plant samples investigated.
Key Word Index
Thapsia - Rouya - Apiaceae (Umbelliferae) - Sesquiterpene lactones - Hydroxylated
guaianolides - Histamine liberators - 6-Methoxy-7-geranyloxycoumarin - Scopoletin
