According to species, dioscorea tubers yield 1% to 8% of total saponins. Diosgenin exists in plant tissues in a combined glycosidal form called dioscin which upon hydrolysis yields diosgenin, glucose and rhamnose moieties. Though diosgenin is the principal sapogenin used by industry, most yams contain a mixture of sapogenins in glycosidic form.

Diosgenin is commercially produced by two methods. From the powdered air-dried drug, the saponin dioscin is extracted using ethanol. The extraction of the glycoside is effected from the plant tissues with ethanol and then the saponins are hydrolyzed by acid treatment to liberate the aglycone which is then extracted with a non-polar solvent. Alternatively diosgenin is extracted by treating the plant tissues with an acidified solution and extracting the aglycone with a non-polar solvent. The first method is more commonly employed and fermentation of chopped tubers for 7 days in the presence of squalene prior to extraction facilitates appreciable increase in sapogenin production. Fermentation loosens the saponins from sugars and the sapogenin production is enhanced in the presence of squalene, which is incidentally an important biogenetic precursor for the production of diosgenin.

A. Method I

1. Dried powdered tubers of dioscorea are finely powdered to 100–200 mesh size. 50 g of this is extracted with 300 ml ethanol in a Soxhlet extractor for 4 h.
2. The ethanol extract is concentrated to one-fifth volume on a rotary vacuum evaporator.
3. To the concentrated extract add 200 ml of 2N HCl and boil under reflux for 6 h for the hydrolysis of dioscin.
4. The flask and its contents are cooled under a stream of water and transferred to a separatory funnel. Extract with 5 × 75 ml of petroleum ether (30% to 60°C) and combine the organic layers.
5. Concentrate the extract to about 100 ml and treat with activated charcoal, filter and load on a column of neutral alumina and elute with chloroform: acetone (3:1)
6. Diosgenin is crystallized from the intermediate fractions and it is purified by recrystallization from methanol/acetone.

B. Method II

1. Add 800 ml of 2N hydrochloric acid to 50 g of finely powdered 100–200 mesh dried dioscorea tubers, in a 1 l round-bottomed flask. Mix well and boil under reflux for 2 h with frequent mixing of the contents.
2. The flask and the contents are cooled under a stream of water and filtered through a Buchner funnel.
3. Wash the precipitate free of acid with 500 ml ice cold water. Press the precipitate between folds of filter paper and dry in an oven at 80°C to a dry brown powder.
4. This residue consisting of crude diosgenin, soil particles and undigested tuber cellulose is placed in filter thimbles and packed into a Soxhlet extractor.
5. Subject it to hot continuous percolation with 300 ml of petroleum ether (30°–60°C) for 6 h.
6. As the extraction proceeds, diosgenin begins to crystallize in the boiling flask.
7. After completion of extraction, reduce the volume of the solvent by evaporation on a steam-heated water bath to about 50 ml.
8. Cool the flask in a refrigerator overnight.
9. Separate the crystallized diosgenin by filtration through a sintered-glass funnel and wash with two 10 ml portions of ice cold petroleum ether.
10. Dry the product by heating at 80°C and note the yield.