Biological activities of saponin components from dupuits and lahontan alfalfa¹

Horber, Ernst; LEATH, K.T.; BERRANG, BERTOLD; MARCARIAN, VICTORIA; HANSON, C.H.

Biological activities of saponin components from dupuits and lahontan alfalfa¹

1974

Horber, Ernst | LEATH, K.T. | BERRANG, BERTOLD | MARCARIAN, VICTORIA | HANSON, C.H.

Saponins of DuPuits and Lahontan alfalfa cultivars were extracted and fractionated by preparative thin-layer chromatography. The ten relatively well-defined saponin fractions obtained from each cultivar were chemically characterized by major aglycone and carbohydrate moieties. Lahontan contained considerably more soyasapogenol A than DuPuits, but medicagenic acid predominated in DuPuits. The near absence of medicagenic acid from Lahontan fractions was the most significant difference in composition of Lahontan and DuPuits saponins. Based on mass-spectrometric analyses, four unidentified sapogenins were classified as the same pentacyclic triterpenoids as medicagenic acid or soyasapogenol. Six Lahontan fractions incorporated varying quantities of galactose, which was present in only two DuPuits fractions, but more arabinose was found in DuPuits than in Lahontan saponins. Simplified saponins of DuPuits and Lahontan were then bioassayed by survival of potato leafhopper (Empoasca fabae (Harris)), survival of pea aphid (Acyrthosiphon pisutn (Harris)), hemolysis of human blood cells, and inhibition of Trichoderma viride Pers. ex Fr. A crude-saponin mixture and a commercially available saponin from Yucca sp. were included in all assays as controls. Certain fractions containing medicagenic acid were responsible for toxic properties in all assays. Presence or absence of medicagenic acid seemed to explain most of the differences in biological activity of DuPuits and Lahontan cultivars. However, medicagenic acid apparently is, not the only acid sapogenin strongly active toward pathogens. An unidentified acid sapogenin chemically related to medicagenic acid inhibited fungal growths markedly, but did not affect insects tested. Potato leafhopper and pea aphid appeared to be appropriate test insects for saponin differentiation.

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