Role of terpenes from Asclepias curassavica latex for antifungal activity

The latex from Asclepias curassavica (Asclepiadaceae) is a secretion produc t exuded from non-articulated laticifers. This latex is an aqueous suspensi on of secretion granules of terpenic nature. These last and the crude latex were tested, alone and in combination with amphotericin B, for their in vi tro antifungal effect on Candida albicans with macrobroth dilution method. The experimental values were treated by non-linear regression. The CMI 80 % of crude latex and secretion particles are respectively 0.874 and 1.605 mg proteins mL(-1). It was possible to determine an affinity constant K-aff f or crude latex (1.683 mg(-1) proteins mL) and secretion particles (0.756 mg (-1) proteins mL). The K-aff is characteristic of the antifungal drug and o f the yeast used; consequently K-aff might constitute a new criterion to es tablish a classification of the various antifungal drugs versus of their ef ficiency on a given yeast type. No synergistic effect between terpenes and amphotericin B was obtained. The essential role of secretion particles as c arrier of glycosidases potentially able to involve a partial fungal cell wa ll degradation is discussed.