Pharmacognosy Sem VII isothiocyanate glycosides

1. Black Mustard
Brassica Nigra

2. Introduction
• Black mustard is cultivated for its seeds, the source of
commercial table-mustard, used as a condiment and
medicine.
• Seeds contain both a fixed and an essential oil, used as a
condiment, illuminant, lubricant, and soap constituent.
• Black mustard is mixed with white mustard (Sinapis alba)
to make mustard flour, used in various condiments as
"English Mustard" when mixed with water and "Continental
Mustard" with vinegar.
• Mustard flowers are good honey producers.
• Mustard is agriculturally used as a cover crop.
• Mustard oil (allyl isothiocyanate) is used in cat and dog
repellents.

3. • Synonym : Brassica Nigra , Brown mustard, Sarso ka tel
• Biological Sources : These are dried ripe seeds of
Brassica nigra Linn., Koch or Brassica juncea Linn,
Czern & Coss, belonging to family Cruciferae.
• Geographical Sources : B. nigra is extensively
cultivated in various parts of Europe and United States.
B. juncea is widely grown in different parts of India and
the CIS-countries (i.e., Russia).

4. Description
• Colour : Black, dark brown or reddish brown
• Odour : Whole seed-none; Crushed seed-pungent
characteristic odour.
• Taste : Bitter
• Size : Approx. 0.9-1.0 mm in diameter
• Shape : Mostly spherical in shape
• Special Features : Seeds are normally covered with a
brittle testa and the kernel is oily and greenish yellow in
colour. The approx. weight of 100 seeds ranges between
150 to 170 mg.

5. Preparation
• The thioglycoside sinigrin is obtained from the defatted black- mustard seed by
employing standard methods. It is usually present in the seeds to the extent of 4%.
• Black mustard seeds are powdered and defatted with petroleum ether. The defatted meal
is boiled with ethanol to destroy the enzyme. The resulting marc is squeezed while hot,
dried at 100°C and maceraed in cold water for 3-4 hours with constant stirring, since
sinigrin is fairly soluble in cold water.
• The liquid content is decanted and maceration is repeated a number of times to ensure
complete extraction of the thioglycoside. The combined aqueous extract is collected and
treated with mild alkalies, such as : BaCO3, so as to neutralize any free acidity.
• The liquid is now concentrated under vaccum to a syrupy consistency. The resulting syrup
is boiled with ethanol (95% w/v) for about 2-3 hours to allow sinigrin to dissolve and at the
same time to precipitate the mucilageous components.
• The alcholoic extracts are filtered and allowed to cool slowly when sinigrin crystallizes out
(approximately 4%).

6. Chemical constituents
• The black mustard seed contains a thioglycoside i.e., a β-glucopyranoside
termed as sinigrin. It is also known as myronate potassium or allyl
glucosinolate as shown under:
• However , sinigrin undergoes complete hydrolysis in the presence of an
enzyme myrocin to yield one mole of each of allyl iso-thiocyanate , glucose &
potassium hydrogen sulphate .

7. • The allyl iso-thiocyanate i.e. the volatile oil component of mustard is solely
responsible for characteristic pungent odour of mustard oils.
• Besides , it contains fixed oil (30%) , proteins (20%) & volatile
oils ( 0.7 – 1.3 %)

8. Chemical Tests
• 1. The powered black mustard seeds on being treated with sodium hydroxide
solution yields bright yellow colouration .
• 2. Chromatographic Evaluation
(a) Paper chromatography of the mustard oil in in a solvent system
consisting of butanol-acetic acid water ; and separately spraying the
chromatogram with 0.02 N silver nitrate solution drying at 100°C and finally
spraying with 0.02 N potassium dichromate produces yellow spots against a
red background of silver chromate thereby confirming the presence of sinigrin.
(b) The thiourea derivatives are used as reference compounds along with
the mustard oil spots in paper chromatography using the solvent system
consisting of water saturated chloroform or butanol-ethanol water. The
chromatogram is sprayed with Grote’s reagent ( i.e. a mixture of sodium
nitroprusside , hydroxylamine and bromine ) which distinctly yields blue spots
with thiourea derivatives as well as sinigrin.

9. Uses
• A paste of black mustard seed is mostly employed in the form of plaster or
poultice as a rubefacient and counter irritant.
• In higher doses , when administered internally , it acts as an emetic .
• Black mustard seeds are invariably used as a widely accepted condiment in
preparation of pickles, curries and vegetables .
• The fixed oil is widely employed as a popular edible oil .

10. Refernces
• http://www.epharmacognosy.com/2012/04/black-mustard-synonym-brown-
mustard.html
• https://www.amazon.in/Being-Marwari-Premium-Black-
Mustard/dp/B07ND3XBQZ
• James A. Duke. 1983. Handbook of Energy Crops. unpublished. Center for
New Crops & Plant Products, at Purdue University Center for New Crops &
Plant Products
• https://slideplayer.com/slide/9003209/
• https://commons.wikimedia.org/wiki/File:Thank-new-yellow-black.svg