2000 parts of dry leaves of digitalis lanata are finely ground with 500 parts of
sodium chloride, they are then wetted with 1000 parts of water and extracted
with 30,000 parts of chloroform. The filtered extract is completely evaporated
in vacuum at a low temperature and to the remaining residue are added 1000
parts of dry ether and the whole mixture is left under the ether until the thick
viscous mass has been transformed into a hard body. The ether is then
poured away and the residue is digested with 1000 parts of ether for about 2
hours under a reflux condenser. After cooling down the mixture, it is filtered,
and the residue obtained, which is now in form of a brittle mass, which is then
dried in vacuum in order to completely eliminate the remaining ether present,
and pulverized. The pulverized mass is advantageously subjected once more
to the treatment with ether. The yellow greenish powder thus obtained is then
dissolved in 1000 parts of methyl alcohol and to the solution, so obtained a
fine suspension of 30 parts lead hydroxide in 1000 parts water is added with
stirring. The solution obtained is neutralized, stirred for about 2 hours, andfiltered, and the clear yellowish filtrate is preferably treated again with a small
quantity of tannin precipitating substance. The clear filtrate thus obtained is
concentrated in vacuum at a low temperature to about 200 parts, whereby the
difficultly soluble portion of the glucoside mixture precipitates. The solution is
then filtered. The precipitate is dissolved in a small quantity of methyl alcohol
and is treated with a small quantity of water whereby the new product begins
to precipitate in a crystalline form. By repeated crystallization from methyl
alcohol, without addition of water, the glucoside may be obtained in the form
of a perfectly pure compound; it does not change its properties even on
further recrystallization. The glucoside, freshly crystallized from methyl alcohol
and dried in vacuo, had MP: 248°C with decomposition, when heated rapidly.
At 230°-235°C, the substance begins to sinter and becomes quite soft; the
melting point, therefore, is not well defined.
Crystallise lanatoside C from MeOH. Its solubility is : 1/17000 (H2O), 1/45 (EtOH) and 1/1500-2000 (CHCl3). [Stoll et al. Helv Chim Acta 16 1049 1933, Stoll & Kreis Helv Chim Acta 35 1318 1952, Okada et al. Chem Pharm Bull Jpn 23 2039 1975, Beilstein 18 III/IV 2455.] It is cardiotonic.
