fig6

Figure 6. The chemical structures of sesquiterpene lactones from other sources. (22) Britannin; (23) Atractylenolide I; (24) Atractylenolide II; (25) Hemistepsin A; (26) Xanthatin; (27) Tagitinin C; (28) Thapsigargin; (29) Antrocin; (30) Gaillardin.