Guaianolide sesquiterpenes from Pulicaria crispa (Forssk.) Oliv.

A phytochemical study of the asteraceous herb Pulicaria crispa (Forssk.) Oliv. resulted in the characterisation of three guaianolide sesquiterpenes, 2α,4α-dihydroxy-7αH,8αH,10αH-guaia-1(5),11(13)-dien-8β,12-olide (1), 1α,2α-epoxy-4β-hydroxy-5αH,7αH,8αH,10αH-guaia-11(13)-en-8β,12-olide (2) and 5,10-epi-2,3-dihydroaromatin (3) by extensive 1 and 2D NMR experiments.