Diosgenin

There are 15 species that existed from which diosgenin can be produced but the major varieties are Dioscorea composita and Dioscorea floribunda. In Indian region Dioscorea deltoidea is prominent (Family- Dioscoreaceae). Most varieties are rich in starch and widely used as edible products. Those varieties which have more than 2 percent of saponin concentration are industrially important. The solasodine is also extracted from the tubers of the Dioscorea. Generally, 3-5-year-old plants produce 1-8 percent of total sapogenin.

Structure of Diosgenin
Fig.1: Structure of Diosgenin
Images of Dioscorea floribunda and D. composita
Fig.2: Images of Dioscorea floribunda and D. composita

Production from Acid Hydrolysis Method

  • Dry the tubers of Dioscorea and reduce its size to 100-200 mesh. The powdered tuber is reflexed or autoclave with 2-4 N mineral acid for about 2-6 hours. Filter the acid and wash the residue with distill water till the solution become neutral.
  • Dry the residue and re-extracted it with hydrocarbon (Petroleum ether) solvent for about 6 hours.
  • Concentrate the liquid and keep it in the refrigerator for 1 hour, the crystal of diosgenin will separate, wash them with acetone.

Incubation and Acid Hydrolysis Method

The fresh tuber is incubated for a few days in water. The incubated drug material was kept with acid for acid hydrolysis. Concentrate the hydrolyzed liquid and further subject to extraction with petroleum ether or hydrocarbon solvent to obtain the diosgenin.

Extraction Form Alcohol

The tubers of Dioscorea are cut into small pieces and sun-dried. Powder the sun-dried tubers and extract with alcohol for 6-8 hours. Filter the extract and concentrate it to the syrupy mass. Then hydrolyze the concentrated syrupy liquid with acids like sulphuric acid and hydrochloric acid for 2-12 hours. Crude diosgenin will be precipitated. Filter the precipitate wash with water and further purify with alcohol.

Fermentation and Acid Hydrolysis Method

The fresh tubers of the plant are collected and smashed with the help of a hammer mill. This smashed product is allowed for fermentation for around two days. Reduce the moisture from the fermented product by sun-drying up to 7-8 percent. Further, the product is hydrolyzed with the help of mineral acid at reduced temperatures. It is then subjected to extraction with hydrocarbon (9 heptanes) to collect the diosgenin. The melting point of diosgenin is 204-207°C.

Estimation

By UV standard curve method.

Prepare solution A (0.5 ml ρ-anisaldehyde in 99.5 ml ethyl acetate) and solution B (50 ml sulphuric acid with 50 ml ethyl acetate). The test samples are dissolved in 2 ml ethyl acetate and add 1 ml of reagent A and B. Stirred well and maintain the temperature of 60°C for 10 minutes to develop the colour. Allow to cool at 25°C and measure the absorbance at 430 nm using ethyl acetate as blank. Similarly, the calibration curve of standard diosgenin (2-70 µg) in ethyl acetate was made and determine the concentration of the unknown sample.

TLC Method

  • Stationary phase: Silica gel G.
  • Mobile phase – Toluene: Ethyl acetate (7:3).
  • Detecting reagent: Anisaldehyde sulphuric acid.

(Compare the standard and sample spot).

HPTLC Method

  • Stationary phase: Silica gel G plate.
  • Mobile phase – n-Hexane: Ethyl acetate (4:2).
  • Detecting reagent: 3 gm of antimony trichloride in 100 ml concentrated HCl.

(Spot of green-black colour is observed the standard and sample are stands by using densitometer).

Utilization

Diosgenin is a very important precursor for the synthesis of a steroidal drug-like sex hormone, corticosteroids, and anti-fertility compounds. The demand for corticosteroids is around 10000 kg but the production is around 4000 kg. The synthetic method for the production of diosgenin is very costly. Natural production of diosgenin is economically feasible. Along with the production of steroidal drugs diosgenin is also used for the treatment of natural hormone replacement therapy or rheumatic arthritis and digestive system improvement.

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