Seasonal changes of saponin content in five alfalfa (Medicago sativa) cultivars

摘要

Five alfalfa (Medicago sativa) cultivars were investigated as regards their saponin content during the growing season. 3GlcA,28AraRhaXyl medicagenic acid and zanhic acid glycosides, expressed as 3GlcGlcGlc zanhic acid, were detected and quantified using HPLC, in order to obtain information on their biogenesis and accumulation in plants. The two more toxic groups of alfalfa saponins were correlated with the presence of biologically active saponins revealed by using Trichoderma viride. Their patternduring the successive harvests showed an increasing level of saponins determined with the T. viride test from spring to summer cuts, and a decreasing trend from summer to autumn, while 3GlcA,28AraRhaXyl medicagenic acid was higher in summer and zanhic acid glycosides higher in late summer and autumn. A possible physiological role of these patterns is suggested.