Antimycobacterial coumarins from the Sardinian giant fennel (Ferula communis)

The structure of a new prenylated coumarin (E-ö-benzoyloxyferulenol, 1b) from the Sardinian giant fennel (Ferula communis) has been confirmed by synthesis. The parent compound ferulenol (1a) showed submicromolar antimycobacterial activity, which was partly retained in 1b and in the simplified synthetic analogue 3, but diminished in its ö-hydroxy and ö-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.