Lucerne saponins II.—Purification and fractionation of saponins from lucerne tops and roots and characterisation of the isolated fractions

Continuous flow paper electrophoresis or column chromatography on alumina of saponin extracts prepared from lucerne tops or roots resulted in the isolation of a saponin fraction. This fraction, which is the main component of root saponin extract but is present only in small amounts in saponins isolated from lucerne tops, consists of glucose, arabinose and xylose as carbohydrate constituents and medicagenic acid, soyasapogenol A and a new, hitherto unidentified sapogenin as aglycones. It is shown that this saponin fraction is the main haemolytic agent and contains almost all of the growth-impairing activity towards Tribolium castaneum larvae. Larval growth can, however, be restored to its normal level by the addition of cholesterol to the diet. Further separation of non-homogeneous fractions obtained on alumina columns resulted in the isolation of individual saponins; examination of their haemolytic activities indicates that both the nature of the sapogenin, i.e., medicagenic acid, as well as the sapogenin/sugar ratio contribute to the extent of this activity.