Allelopathic potentials of alfalfa (Medicago sativa) saponins: Their relation to antifungal and hemolytic activities.

A wheat seedling bioassay was used to indicate the relationship between the chemical structure of alfalfa saponins and their allelopathic activity. None of the tested saponins significantly influenced wheat germination. Seedling growth bioassays indicated significant differences among the activities of individual glycosides. The most active were medicagenic acid, its glycosides substituted at the C-3 position with glucose, and hederagenin monoglycoside. Medicagenic acid glycosides, substituted at the C-3 position with glucuronic acid, and zahnic acid tridesmoside were less active. No significant correlation was found among the allelopathic, hemolytic, and antifungal activities of the individual glycosides.