In vitro evaluation of antifungal activity and interactive effect of Anadenanthera colubrina (Benth)

Anadenanthera colubrina (Benth) Brenan, a plant known in the Northeastern Region of Brazil as angico, is widely used in traditional folk medicine to treat respiratory and inflammatory diseases. This study aimed to evaluate the antifungal activity, determine the minimum inhibitory concentration (MIC), the minimum fungicidal concentration and the fungal kinetics (death curve) in addition to the interactive effect of the dry extract of angico in association with the antifungals fluconazole and nystatin against yeasts of the genus Candida. The dry extract was obtained by rotoevaporation. Tests for evaluation of antifungal activity, determination of the MIC and the MFC as well as the evaluation of the interactive effect with conventional antifungal were done by disk diffusion and microdilution technique. For the evaluation of the angico’s effect on fungal growth, death curve was utilized. The results show the angico’s antifungal potential in all of the strains tested, having MIC of 1.0 mg/mL. It was observed that the fungal kinetics of 2x MIC, MIC and ½ MIC had similar effects; 6 h was their best time after incubation. There was fungistatic activity reduction (2 log 10 UFC/mL) from the initial inoculum of 1.0 mg/mL. Interactive effect was not observed when used in association with nystatin, but showed synergistic effect when used with fluconazole. In these data, one can see that angico is a species rich in biological activity; being promising species, the isolation and detection of its bioactive compounds is necessary.