Abstract

Antifungal activity of water, ethanol, lanolin and cocoa butter plant extracts derived from seven Mexican Chihuahuan desert inhabiting plant species (Larrea tridentata, Flourensia cernua, Agave lechuguilla, Opuntia ficus-indica, Lippia graveolens, Carya illinoensis and Yucca filifera) were evaluated against Phytophthora cinnamomi. All plant extracts were active against Phytophthora cinnamomi. Two (L. tridentata and F. cernua) out of seven plant species tested had the optimal antifungal activity against this fungus specie, with minimum inhibitory concentration (MIC) values as low as 6.96 and 8.6 mg/L. Some of the plant extracts had moderate to low activity against P. cinnamomi, and the variations of active polyphenolic (condensed and hydrolysable tannins) compounds in the plant extracts estimated via colorimetric methods indicated that the inhibitory activity may not based on a general metabolic toxicity but perhaps the antifungal potency is conferred by group or groups of toxic metabolites. Based on the antifungal activity, crude plant extracts may be a cost effective way of protecting crops against P. cinnamomi. Because plant extracts contain several antifungal compounds, the development of resistant pathogens to these plant extracts may be delayed.

Key words: Antifungal activity, plant extracts, polyphenols, MIC₅₀ P. cinamomi.