Eurobusones A-D, four antibacterial formyl phloroglucinol meoterpenoids from Eucalyptus robusta

Four antibacterial formyl phloroglucinol meroterpenoids (FPMs), eurobusones A-D (1–4), as well as six known analogues (5–10), were isolated from the leaves of Eucalyptus robusta. Their structures were determined by the analysis of spectroscopic data and electron circular dichroism (ECD) calculation, along with the application of Snatzke helicity rules. Among them, compounds 2 and 8–10 showed good activity against Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis with MIC50 values less than 1.00 μg/mL.