galbanic acid, a sesquiterpene coumarin from ferula szowitsiana , and conferol, another sesquiterpene coumarin from f. badrakema , were evaluated for their effects on the reversal of multi-drug resistance in clinical isolates of staphylococcus aureus and escherichia coli , respectively. neither galbanic acid (up to 1000 μg/ml) nor conferol (up to 400 μg/ml) by itself shows any antibacterial act...