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BACKGROUND
Synonym of Indian Senna is Tinnevelly senna, Cassia senna. It consists of dried compound leaflets of Cassia angustifolia belongs to family Leguminosae. Mostly its cultivation is done in Tinnevelly, Madurai, Rajasthan, Gujurat and Andhra Pradesh. The plant is a small shrub having 3-7 pairs of leaflets. The drug should be protected from light during its storage. The major chemical constituent is sennoside-A and sennoside-B which are anthraquinone glycoside. Both show stereoisomerism. Borntrager’s test confirms the presence of anthraquinone.1
Aim: Aim of the experiment is to isolate and detect the active constituent, sennoside present in senna.
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REQUIREMENTS
Apparatus: Electronic shaker,
Distillation unit,
Extraction unit,
Dessicator,
Test tube,
Conical flask,
Funner,
Filter paper,
Water bath
Chemicals: Benzene,
70% methanol,
HCl, calcium chloride,
Ammonia,
P2O5,
Oxalic acid,
Methanol,
Triethylamine,
Calcium chloride
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PROCEDURE
Isolation of sennoside
Method-1:
Make dried and powdered sample. For two hours the sample is shaken with benzene on an electronic shaker. The solvent is filtered and distilled followed by drying at room temperature. With 70% methanol, the sample is extracted for 5-6 hours and the extract is filtered under vacuum followed by re-extraction again for 2 hour and filtrate is collected. The methanolic extract sample is combined and concentrated in to 1/8th portion of its initial volume. Using HCl the concentrated sample is acidified to a pH of 3.0-3.2. At 5ºC temperature, the acidified sample is kept aside. The sample is filtered and anhydrous calcium chloride is added by dissolving in 25 ml of denatured spirit with vigorous stirring. By using ammonia the pH is adjusted to 8 and it is kept aside for 1-2 hour. Finally the sample is filtered and the obtained precipitate is dried by using P2O5 in a dessicator.2
Method-2:
By shaking with ethanolic chloroform for 30 minutes, the powdered drug sample is extracted (chloroform: ethanol = 93:7). Again the extraction is carried out by using acidic methanol. Acidic methanol is prepared by using 1.2 g of oxalic acid per litre of methanol. Both the extracted sample is combined and concentrated. This sample is allowed to stand for overnight at room temperature. Then sennoside-B remains in solution and sennoside-A is precipitated. Re-crystallization of sennoside-A is carried out using triethylamine and precipitation of sennoside-B is carried out by 10% methanolic solution of calcium chloride. Again the sample is separated by methanolic ammonia solution. This solution is prepared by adding 60 ml of methanol and 40 ml of ammonia. The sample is wasedand dried with water and allowed to stand for one day followed by re-crystallization using glycolmonoethylether.2
Detection of sennoside
Different organic solvent like benzene, ether, chloroform is added to the sample and shaken. The organic layer is separated and ammonia solution is added to it. Pink or red colour is produced by confirming the ammonical layer which shows the presence of anthraquinone.
TLC of sennoside
The solvent system is ethyl acetate:methanol:water having ratio 100:16.5:13.5. The obtained purified sample is spotted in the plate of silica gel and developed in ethyl acetate:methanol:water .When the dried plates of silica gel is sprayed with HNO3 (25%), red coloured spots will be seen. After drying with alcoholic KOH red colour is converted in to yellow colour.2
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CONCLUSION
The active constituent sennoside was isolated and detected from senna. It is used as purgative, stimulant laxatives.
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REFERENCES
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Kokate CK, Purohit AP, Gokhale SB. Druds containing alkaloid (belladonna), Text Book of Pharmacognosy, 51 edition, Nirali Prakashan, pune. 2015: 9.24.
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Shah B, Seth AK. Isolation of phytopharmaceuticals, Text book of Pharmacognosy and Phytochemistry, 2nd edition. CBS Publishers & Distributors pvt ltd. 2014: 460.
