The objective of this study was to investigate the interference of the polar and apolar fraction as well the essential oil of Baccharis dracunculifolia DC., Asteraceae, about the antibiotics effects used in the medic clinic. The essays were accomplished with twenty nine antibiotics in association with two extracts [one polar fraction (HA 50%) and one of apolar fraction (EA 25%)] and with essential oil. The method used was the diffusion one in solid mean using the antibiotic discs, which were acquired commercially. The results showed interference in the hoped action of the antibiotic when associated to the extract and to the B. dracunculifolia essential oil. In some cases there was no alteration of the antibiotic action, however, in most of the cases there was either a synergic or an antagonic interference of the antibiotic action. These outcomes have showed that the use of derived products or plants can interfere on the effectiveness of the antibiotic use in the clinic treatment, in some situations.
medicinal plants; essential oils; antibiotics; associated use; interference; Baccharis drancunculifolia
