Studies on the chemical constituents of Eucalyptus robusta Sm.: Isolation and identification of robustaol B and other constituents

Nine known compounds, 5‐hydroxy‐4′,7‐dimethoxy‐6,8‐dimethylflavone, 4′,5‐dihydroxy‐7‐methoxy‐6,8‐dimethylflavone, 3β‐hydroxy‐urs‐11‐ene‐28‐oic‐13(28)‐lactone, 3β‐acetoxy‐urs‐11‐ene‐28‐oic‐13(28)‐lactone, uvaol, β‐sitosterol, 7β‐ O ‐glucoside of 5,7‐dihydroxy‐2‐methylchromone, 1‐triacontanol and 1‐triacontanoic acid, and a new acylphloroglucinol named robustaol B 6 were isolated from the leaves of Eucalyptus robusta Sm. 6 was shown to be 4,6‐dihydroxy‐2‐methoxy isobutyrophenone by spectral analyses and was confirmed by synthesis. 6 showed inhibition against Staphylococcus aureus 209P and Bacillus subtilis 6633 in vitro.