78338-24-6 BRUCEANTIN-5'-OL MC-31-BC NSC317018 Picras-3-en-21-oic acid, 13,20-epoxy-3,11,12-trihydroxy-15-[(5-hydroxy-3,4-dimethyl-1-oxo-2-pentenyl)oxy]-2,16-dioxo-, methyl ester, [11.beta.,12.alpha.,15.beta.(E)]-