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Name: Pfungwa Gervase Makoni Student Number: 46502572

Course code: CHE4808 Degree Programme: Bachelor of Science Honours in Chemistry

Project proposal

Title of Project: Extraction, separation and identification of the natural oils found in a tuber

used traditionally for medicinal and other purposes.

Supervisor: Professor M J Mphahlele

Proposed submission date: October 2012

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Field of research/ Provisional Title

There are many natural plants that have medicinal value and are used widely to alleviate

ailments; one such plant is ginger root. Natural products contain millions of compounds and

these fall mainly into four types: alkaloids, polyketides, terpenes and steroids (Clayden et al,

2001, p.1413). These compounds are called secondary metabolites because they are

synthesized by living organism for specific life processes. Ginger root is a rhizome of the

plant Zingiber officinale. In this project I endeavour to extract, separate and identify the

natural oils that are found in ginger root which is a rhizome of the plant Zingerber officinale

using chromatographic, analytical and spectroscopic techniques.

Context of the research project

Zingerber officinale cultivation began is South Asia and has spread to Eastern and Southern

Africa and the Caribbean. Extracts from ginger are used in foods, condiments, baked

confections, candies, beverages, cosmetics and perfumes. Ginger can also be used as a

medicinal herb and it is readily available in most supermarkets. China produces ginger which

is particularly suited for confectionery, while Japanese ginger lacks the typical aroma.

Overall ginger products vary considerably in taste, pungency and smell, while the rhizome,

which is the useful part of the plant, varies in consistency depending on the country of

origin (UCLA Louise M. Darlington Biomedical library, n.d).

Zingerber officinale (ginger root) is used widely as a medicine, a delicacy and spice3,(Chang

CP et al, 1995, p.13-19). It can also act as a food preservative and is also used in beverages

and making some types of bread and cookies. Because of its popularity among the African

natives and its medicinal purposes ginger root contains a number of natural oils which are

highly beneficial to mankind. There are no known side effects of the use of the tuber

although overdoses are generally discouraged.

Some of the ailments that ginger root are known to cure are: stomach pain, skin cancer,

nausea in pregnant mothers (herbal-supplements-guide.com, n.d). Ginger contains oils that

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control the quantity of free radicals and the peroxidation of lipids and could prevent or

reduce the damage caused by these in the human body. Ginger also relieves muscle pain

due to exercising. Other studies suggest that ginger has blood thinning and cholesterol

lowering properties and can relieve pain caused by arthritis (N Perez, 2005). So the effects

of ginger seem vast and make it an important tuber.

Since ginger root has such properties it is necessary to extract, separate and identify the

natural oils that are it. This will give an indication of the oils that give it its properties and

hopefully shed some light into some drugs that can be developed synthetically for

treatment of ailments. Most of the studies that have been done to date were based on the

western and eastern countries like China and the States. It is therefore necessary to work on

the African breed of the ginger root to see if they produce similar natural oils.

Research has shown that the major active ingredients in ginger are compounds called

terpenes. The characteristic odour and flavour of ginger is caused by a mixture of zingerone,

shogaols and gingerols (Govindarajan VS, 1982; p.1-96.) Preliminary research indicated that

there up to nine compounds found in ginger. Research on the ginger from China and that

from Guinea showed a difference in the composition or quantities of the constituents (A

Toure and Z Xiaoming, 2007, p350-355).

The structures of some of the compounds that have been associated with ginger root are

shown below:

1. Terpenes

The International Journal of Biomedical, 2010, p.233-240 gives the following structure as

that of a common terpene.

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2. Gingerols and shagaols

These are polyphenolic compounds which produce a characteristic pungent smell of ginger.

Shagaols are the dehydrated forms of gingerols. Suzanna M Zick et al in their work on the

quantitation of gingerols and shagaols in human plasma by HPLC obtained the sited the

following structures for gingerols and shagaols in their publication (M Zick at al, 2010, p.

233-240)

3. Camphene

There are many other compounds that contain carbon –carbon pi bonds (alkenes) that have

been detected in ginger root. These include camphene shown below, beta- myrcene,

copaene and alpha-phellandrene (Edgar 181/PD, chemistry.about.com)

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The chromatograms obtained by A Toure and Z Xiaoming in their Gas

Chromatographic analysis of volatile components of Guinean and Chinese Ginger Oils

published in the Journal of Agronomy 2007; 6(2): (p. 350-355) are shown below:

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The goals of the research project

The major goals of this research are to identify the active natural oils in ginger root and

hopefully their stereo chemical properties. However, this can only be achieved after a

successful extraction and separation of the oils. It is expected that ginger root being a

natural tuber will have several organic and inorganic components in it. The key to the

success of the project will be the success of the extraction and separation.

As ginger root has many properties it will be ideal to identify the substances that give it

these properties. The key to being able to synthesise these natural oils lies initially in being

able to identify the active ingredients of this tuber. These ingredients can be identified

firstly by finding the functional groups in the various oils.

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Methods; procedures and techniques

The tubers are to be obtained, crushed and frozen to ensure that the volatile oils that give

ginger root its characteristic pungent smell do not evaporate away. The ginger root will be

divided into 2 portions so that 2 methods of extraction will be carried out. One portion will

be treated to steam distillation to try and harvest the volatile oils. In steam distillation, the

steam is forced over the ginger, as this happens the steam will help release the aromatic

molecules from the ginger. These oils escape from the ginger plant into the vapour phase

and are driven by the steam to a condenser. The temperature of the steam must be

carefully controlled to avoid the decomposition of the oils as some of the natural oils easily

decompose on heating. This is why the steam distillation principle is essential as it makes

the oils to boil at temperatures lower than their normal temperatures reducing the risk of

the oils decomposing.

The other portion will be treated to solvent extraction where it is shaken in 2 immiscible

solvents, one of them being polar (H2O) and a non-polar solvent. The two immiscible

solvents will then be separated and the oils harvested from the solvents. The oils extracted

by steam distillation should be immiscible with water and so they can be separated easily

from the water. Solvent extraction will harvest the non-volatile components from ginger

root. The principle relies on the partitioning of the natural oils between the two phases so

that the oils are harvested from the ginger root and distribute themselves into the

harvesting solvents.

After extraction the harvested oils will be purified using chromatographic techniques. There

are several chromatographic techniques that can be used to separate the natural oils.

Column chromatographic techniques like Gas-Liquid chromatography (GLC) and High-

Performance Liquid chromatography (HPLC) will be more ideal as they do not destroy the

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sample and the recovery of the sample is easier. The two techniques mentioned above are

also fast and very efficient.

The various portions are then prepared for identification of pertinent functional groups

using Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic

resonance (H NMR) techniques. If possible the structural formula of the oils will be deduced

and stereo chemical properties also deduced. Other techniques like mass spectrometry may

be used as well.

The techniques mentioned above are used because they have been found to be effective

and have been used widely by researchers. All the techniques used are known to retain the

samples and to produce fair yields which can be used for analysis. They are also fast and

have high resolutions.

Provisional table of contents

Abstract

Introduction

Extraction of oils

Separation of oils

Identification of functional groups and oils

Results

Analysis

Reference and acknowledgements

Acknowledgements

1. To my supervisor Professor M J Mphahlele for your patience, valued guidance,

timeous response to all my queries and going through my proposal on numerous

occasions your assistance and wisdom is much appreciated.

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2. To my friend and confidante who took the time and pain of proofreading, guiding me

with the structure and referencing Vuyokazi Gontshi of Rhodes University library,

your help, enthusiasm and friendship is priceless. Thank you.

3. To a brother and fellow friend Doctor M Mujuru for taking time to read my proposal,

thank you sir.

References

1. Clayden, Greeves, Warren and Wothers: Organic Chemistry, Oxford University

Press: p1413

2. “Spices: Exotic flavours and Medicines: Ginger”.

http://unitproj.library.ucla.edu/biomed/spice. [Retrieved 22 May 2012].

3. Grant KL, Lutz RB, Ginger, Am J Health Syst Pharm 200 (57): p.945-947. Available

through: http://www.thorne.com/altmedrev/fulltext/8/3/331.pdf. [Accessed 18

June 2012]

4. Chang CP, Chang JY, Wang FY, Chang JG: the effect of Chinese medicinal herb

Zingiberis rhizoma extract on cytokine secretion by human peripheral blood

mononuclear cells. J Ethnopharmacol 1995; 48: p.13-19. Available through:

http://samahan.linknaturalproducts.com/downloads/pds-samahan.pdf. [accessed 25

May 2012]

5. “Benefits of ginger root”. http://www.herbal-supplements-guide.com/benefits-of-

ginger-root.html. [Accessed 25 May 2012]

6. N. Perez: Aromatherapy times, Journal of International federation of Aromatherapists 2005;

63 (1). Available through:

http://www.holisticaroma.co.uk/articles/EssentialOilofGinger-

Zingiberofficinaleroscoe. [Accessed 25 May 2012]

7. Govindarajan VS, Ginger-Chemistry, technology, and quality evaluation: part 2. Crit

Rev Food Sci Nutr 1982; 17:1-96.

8. Alhassane Toure and Zhang Xiaoming: Gas Chromatographic analysis of volatile

components of Guinean and Chinese Ginger Oils extracted by steam distillation.

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Journal of Agronomy 2007; 6(2): 350-355. Available through:

http://docsdrive.com/pdfs/ansinet/ja/2007/350-355.pdf [accessed 25 May 2012]

9. http://chemistry.about.com/od/factsstructures/ig/Chemical-Structures---C/Camphene.htm.

[Accessed 18 June 2012]

10. S M Zick, M T Ruffin, Z Djuric, D Normolle and D E Brenner: Quantitation of 6-, 8- and

10-Gingerols and 6-Shagaols in Human Plasma by High Performance Liquid

Chromatography with Electrochemical Detection. International Journal of Biomedical

Science 6(3), p. 233-240. Available through:

http://ijbs.org/User/ContentFullText.aspx?volumeNO=6&StartPage=233. [Accessed 18 June

2012]

11. http://chemistry.about.com/od/factsstructures/ig/Chemical-Structure---C/Camphene.htm.

[Accessed 18 June 2012]