4,5-.alpha.-Epoxy-6-.beta.-hydroxygermacra-1(10),11(13)-dien-12-oic acid gamma-lactone 4,5-.alpha.-Epoxy-6-.beta.-hydroxygermacra-1(10,11(13)-dien-12-oic acid .gamma.-lactone NSC157035 Oxireno[9,10]cyclodeca[1,2-b]furan-9(1aH)-one, 2,3,6,7,7a,8, 10a,10b-octahydro-1a,5-dimethyl-8-methylene-, (1aR,4E,7aS,10aS,10bR)- (9CI)- Parthenolide