Antifungal activity of hydrosoluble extracts of plants from Coahuila desert

Fungicidal activity of extracts of wild plants Larrea tridentata, A. lecheguilla and Carya illinoinensis (nut) was evaluated against the fungi Aspergillus ustus., Aspergillus niger, Penicillium spp., Mucor griseocyanus and Fusarium oxysporum. Extracts were prepared from 10g of dried plant powders (leaves and stems) and nut crushed shell, using water or ethanol. The extracts were mixed with PDA agar at 45–50°C at 1:4; 2:3 and 3:2 relations on Petri dishes. Each assay was performed at triplicate. The Petri dishes were inoculated with spore suspensions or mycelium piece of 5mm of diameter. The inoculated dishes were incubated at 28 +/- 2°C for eight days. The radial growth of mycelium (diameter of colony) were measured each 24h to compare with measurements in control assay without extracts. Concerning antifungical activity, Larrea tridentata, extracts was the most active against Aspergillus ustus., Aspergillus niger, Penicillium spp., Mucor (MIC of 5.5 to 8.5mg/ml of tannins total) whereas A. lecheguilla and Larrea tridentata mixtures exhibited the best activity against Fusarium oxysporum (MIC of 900 ppm and 4.27mg/ml, respectively). It was demonstrated that extracts of L. tridentate and A. lecheguilla applied at different concentrations as well as their mixtures were effective to inhibit the mycelium growth of 5 fungi, while shell extracts of Carya illinoinensis were not demonstrated fungicidal activity. This effect may be related with the presence of hydrolysable tannins and saponins.