78338-23-5 BRUCEANTIN, 4',5'-EPOXY MC-27-BA NSC317019 Picras-3-en-21-oic acid, 13,20-epoxy-3,11,12-trihydroxy-15-[[3-(2-methyloxiranyl)-1-oxo-2-butenyl]oxy]-2,16-dioxo-, methyl ester, [11.beta.,12.alpha.,15.beta.(E)]-