Antimycobacterial Coumarins from the Sardinian Giant Fennel (Ferula communis)

The structure of a new prenylated coumarin (E-ω-benzoyloxyferulenol, 1b) from the Sardinian giant fennel (Ferula communis) has been confirmed by synthesis. The parent compound ferulenol (1a) showed sub-micromolar antimycobacterial activity, which was partly retained in 1b and in the simplified synthetic analogue 3, but diminished in its ω-hydroxy and ω-acetoxy derivatives (1c and 1d, respectively). The outstanding activity of 1a, its low toxicity, and the evidence for definite structure−activity relationships make this prenylated 4-hydroxycoumarin an interesting antibacterial chemotype worth further investigation.