Digitalis Saponins. II. Leaf Saponins of Digitalis purpurea L.
Abstract
As the leaf saponins of Digitalis purpurea L. two saponins, I and II, were detected on a paper chromatogram and isolated by column chromatography on alumina. With the aid of thin-layer chromatography I was found to be composed of two saponins, I-1 and I-2, while II to be a mixture of six (three pairs). I-1 and I-2 were obtained in pure state according to the Tschesche method and characterized, respectively, as tigogenin- and gitogenin-tetraglycosides both of which equally have one mole each of D-galactose and D-xylose and two moles of D-glucose as the sugar moieties. I-1, m.p. 284∼286°(decomp.), [α]28D-64.0°, was named desgalactotigonin and I-2, m.p. 252∼255°(decomp.), [α]25D-58.5°, F-gitonin. Three pairs of saponins in II were assumed to be penta-, hexa- and hepta-glycosides and each pair was presumed to consist of tigogenin- and gitogenin-glycosides both of which might have the same sugar composition.