Propyl gallate increases in vitro antifungal imidazole activity against Candida albicans

We looked at the in vitro effect of an antioxidant, propyl gallate (PG), on the antifungal activity of miconazole sulphosalicylate, econazole sulphosalicylate and ketoconazole against 40 clinical isolates of Candida albicans. The combination of imidazole and PG gave MIC values 10-150 times lower than those of imidazole alone. The optimal conditions for this enhanced activity were pH 6.2-8.0 and a fungal cell concentration lower than 3 x 10(5) cells/ml. The mechanism of the interaction between imidazole and PG is not known but may be as a result of an effect of PG on the P-450 cytochrome. Theoretically this combination could reduce the side effects of long treatment with imidazoles and lower the risk of resistance to these antifungal drugs.