Helenin546-43-0100 % similar (+)-Isoalantolactone470-17-735 % similar (-)-Xanthatin26791-73-133 % similar 2,2,6-Trimethylcyclohexanone2408-37-931 % similar Parthenolide20554-84-131 % similar Arglabin84692-91-131 % similar