Rhubarb Biological Sources, Morphology, Chemical Constituents, Adulterants and Uses

Rhubarb Biological Sources, Morphology, Chemical Constituents, Adulterants and Uses

Rhubarb is anthraquinone glycoside.

Rhubarb

Synonym :-

Rheum, Rhizome Rhei, Rhubarb Rhizome

Biological Source :- 

It is consists of the dried rhizome of Rheum emodi (Indian rhubarb), Rheum Webbianum (Chinese rhubarb), Rheum Palmatum

Family :-  Polygonaceae

Geographical Source :- 

It is obtained both from wild and cultivated species grown in region from South East to China to tibet and korea.

It is perennial herb. It grows on topical and sub-tropical climate. It grows upto 2M.

Morphology Characteristics :-

Shape :- Rhizomes are conical, sub -cylindrical, barrel shaped and plano-convex shape.

Size :- 3 to 12 cm long, 3 to 8 cm in diameter

Odour :- Aromatic

Taste :- Astringent

Surface :- The surface shows a network of reddish brown lines embedded in a whitish matrix & numerous star spots.

Chemical Constitutions :- 

  • Rhein & glucorhein ( Carboxyl group anthra quinones)
  • Palmidin A → Aloe – emodin anthrone + emodin anthrone
  • Palmidin B → Aloe – emodin anthrone + Chrysophanol anthrone
  • Palmidin C → emodin-anthrone + Chrysophanol anthrone

Chemical Test :-

  1. Rhubarb give positive test for modified borntrager’s test.
  2. Rhubarb shows red colour with addition of alkalies due to presence of anthraquinone glycoside.

Uses :- 

  • Rhubarb is used as laxative drug. In larger dose it act as purgative.
  • In small doses it is a bitter stomachic and intestinal astringent.

Adulterants :- 

  • English Rhubarb (Rheum officinale) and indian rhubarb are used as substitute while rhapontic rhubarb (Rheum rhaponticum) and the stock roots of rumex alpinus and Rumex obtusifolius are used as adulterant of the official drug.

MCQ

1. Star spot is special feature of which plant ?

A. Ginger

B. Aloe

C. Capsicum

D. Rhubarb

2. Which sentence is false about Rhubarb?

A. It has a special feature of the surface is called a starspot.

B. It is purgative in nature.

C. It is only grown in sub-tropical region.

D. It is belong to family Polygonaceae.

3. Which herb give positive result for modified borntrager’s test ?

A. Seena

B. Rheum

C. Fox glove

D. Snake root

4. Which sentence is false about Rhubarb ?

A. It has special feature of star spot.

B. It is belong to family Polygonaceae.

C. It is use as purgative.

D. It is belong to family leguminosae.

5.Rheum emodin is also known as 

A. England Rhubarb

B. Indian Rhubarb

C. Chinese Rhubarb

D. Russian Rhubarb

6. Which of the following species is adulterant of rhubarb ?

A. Rheum palmatum

B. Rheum modi

C. Rheum rhaponticum

D. Rheum Webbianum

7. Which of the following is not use of rhubarb ?

A. Purgative

B. Astringent

C. Laxative

D. Hypertension

8. Which of the following is substitute of Indian Rhubarb ?

A. Rheum Webbianum

B. Rheum officinale

C. Rheum modi

D. Rheum palmatum

9. Which sentence is true about Rhubarb ?

A. It is use in hypertension.

B. It is use in constipation.

C. It is use in pregnancy.

D. It is use in ICH.

10. Rheum Webbianum is also known as

A. England Rhubarb

B. Indian Rhubarb

C. Chinese Rhubarb

D. Russian Rhubarb

Answer key 

1. D

2. C

3. B

4. D

5. B

6. C

7. D

8. B

9. B

10. C

Reference :- 

16 edition of trease and evans Pharmacognosy ( pg.no.244 and245)

Rhubarb-based Chinese herbal formulae for hepatic encephalopathy: a systematic review and Meta-analysis

https://www.sciencedirect.com/science/article/pii/S0254627218300359

This information is taken only for education purpose

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