An Improved Procedure for the Isolation of Medicagenic Acid 3-O-β-D-Glucopyranoside from Alfalfa Roots and Its Antifungal Activity on Plant Pathogens

2β-Hydroxy-3β-O-(β-D-glucopyranosyl)-Δ¹²-oleanene-23,28-dioic acid, known also as medicagenic acid 3-O-β-D-glucopyranoside, was isolated from alfalfa roots in pure form and was shown to possess potent fungistatic effects against Trichoderma viride, Sclerotium rolfsii, Rhizopus mucco, Aspergillus niger, Phytophthora cinamommi, and Fusarium oxysporum f. sp. lycopersici: i.e., mycelial growth inhibition of 95%, 86%, 68%, 53%, 51%, and 52%, respectively, for concentrations of 40 μg/mL and ID₅₀ of 1.4, 2.3, 4.1, 1.7, 40, and 10.5 μg/mL, respectively.