Antifungal activity of various saponins from Medicago arabica

Eight saponins isolated from the aerial parts of M. arabica were tested for their antifungal activity against Gaeumannomyces graminis var. tritici which causes take-all disease in cereals. Three of the test compounds were monodesmosides (sugars linked at the C-3 position) of bayogenin and hederagenin and were most stronger inhibitors of mycelial growth of the fungus than bidesmosides (with sugars linked at C-3 and C-28 positions of aglycones). The most inhibitory compounds were 3-O-[β-D-glucopyranosyl(1→2)-α-L-arabino-pyranosyl] hederagenin and 3-O-α-L-arabinopyranosyl bayogenin with EC₅₀ equal to 11.9 and 13.7, respectively.