Enhanced antifungal activity of ketoconazole by Euphorbia characias latex against Candida albicans

The in vitro suseptibility of Candida albicans to ketoconazole and Euphorbia characias latex alone or in combination was tested using the macrobroth dilution method. The MIC 80% of crude latex and ketoconazole are respectively 159 microg protein/ml and 0.3901 microg/ml. This method permits us to determine an affinity constant K(aff) for crude latex (0.015 microg(-1) protein ml) and ketoconazole (23.828 microg(-1) ml). The utilization of a mixture of latex at several concentrations (7.8-15.62-31.25-62.5 and 125 microg protein/ml) and ketoconazole indicates a synergistic effect between latex and ketoconazole. For latex concentrations of 31.25 and 62.5 microg protein/ml the MIC 80% of ketoconazole were inferior (0.194 and 0.183 microg/ml respectively) to that obtained with ketoconazole alone (0.390 microg/ml). A synergistic effect is therefore obtained between ketoconazole on the one hand and two concentrations of Euphorbia characias latex.