Abstract
When ?5–
sapogenin, such as diosgenin, was shaken with a 25 % solution of antimony trichloride
in 60 % perchloric acid, a pink colour („kmax 500 nm) which obeyed Beer's Law was
produced, at room temperature. The accurate determination of diosgenin in the presence
of either phytosterol or a limited amount of fixed oil was achieved by the addition
of a small amount of a mixture of chloroform and absolute ethanol, 1:1. The relative
standard deviation was 3 % on 50 μg of pure diosgenin and 6 % on a crude extract (of
Dioscorea deltoidea tuber) containing the equivalent of 50 μg of diosgenin. The procedure gives the ?5–
sapogenin content calculated as diosgenin. Detection of other ?5–
sapogenins is effected by TLC of the crude extract.
