Terpenes, Volatile oils and other compunds

Question 1

Volatile oils also referred to as

Answer 1

ethereal’ and ‘essential oils

Question 2

___________will evaporate into the atmosphere if left exposed.

Answer 2

volatile oils (cf. Fixed oils)

Question 3

State the characteristics of essential oils /Volatile oils

Answer 3

They are generally complex mixtures
Have an associated smell (useful for identification)
Are often optically active
Have a high refractive index
Not very soluble in water but soluble in organic solvents,
They are prone to oxidation (colour change).

Question 4

List types of compounds present in Volatile oils

Answer 4

Terpenoids(mainly monoterpenes)
Phenylpropane compounds,
Simple alcohols (methanol, ethanol)
and occasionally any one of the major compounds as a glycoside (linkage to a sugar)

Question 5

_____________form one of the largest groups of compounds, occurring in plants, animals and insects, and many other organisms.

Answer 5

Terpenoids

Question 6

Functions of Terpenoids are still not realised for most of the compounds
____________have hormonal function
_________ have antioxidant function
__________ possess antibacterial and antifungal activity
some ___________ occurring in plants have deterrent properties

Answer 6

Sterols

Carotenoids

Sesquiterpenes

terpenes

Question 7

What are terpenes?

and isoprene units are made of?

Answer 7

These are composed of isoprene units (derived from acetylCoA molecules) condensed together under enzymatic control.
An isoprene unit is a branched five-carbon unit (C5H8).

Question 8

Mention the four(4) main groups of Terpenoids

Answer 8

Monoterpenes
Sesquiterpenes
Diterpenes
Triterpenes

Question 9

A compound that contains two isoprene units is known as

Answer 9

Monoterpenes C10H16

Question 10

A compound composed of three(3) isoprene units

Answer 10

Sesquiterpenes (C15H24)

Question 11

A compound composed of four(4) isoprene units

Answer 11

Diterpenes (C20H32)

Question 12

A compound composed of six(6) isoprene units is called

Answer 12

Triterpenes

Question 13

List the different types of reaction that increase the range of terpenoids compound

N/B: _____________present will influence the compounds that will exist in plant

Answer 13

Cyclization and Oxidation reactions

N/B: The type of reaction present will influence the compounds that will exist in plant

Question 14

The structure of monoterpenes found in volatile oils may be ______________

Answer 14

linear, monocyclic, or bicyclic.

Question 15

Facts about Geraniol ( hint it is present in 7 things) (has 3 agents)

Geraniol is ___________

Answer 15

Geraniol is an important constituent of essential oil of ginger, lemon, lime, lavender, nutmeg, orange and rose. It has been reported to have cytoprotective, antioxidative and anti-carcinogenic agent.

Geraniol is an example of Linear Monoterpenes

Question 16

Eucalyptus oil is a volatile oil used for……..

Answer 16

Inhalation/decongestion

Question 17

What is the therapeautic use of Peppermint?

Answer 17

Carminative

Question 18

What is the therapeautic use of Begarmot/Cinnamon?

Answer 18

Flavouring

Question 19

What is the therapeutic use of Clove?

Answer 19

Tooth Tincture/Antiseptic

Question 20

What is winter green used for ?

Answer 20

Analgesic

Question 21

What is Rose/Lavender used for

Answer 21

Perfumery/Cosmetics

Question 22

What are Phenylproprane compounds?

Answer 22

Nine(9) carbon-based compounds that have an aromatic ring

Question 23

The biosynthesis of Phenylproprane compounds is from ……….

Answer 23

Shikimic acid

Question 24

State the two main methods of extracting oil from it plant source

Answer 24

1. Distillation(Two main types of distillation processes are used.)

• Water distillation – Boiling the plant material in water. The water vapour and the oil condense separately. The oil forms a layer on the water and is then collected. Cannot be used for oils that decompose easily.
• Steam distillation – The plant material, suspended in a basket, is treated with steam. The oil is recovered at a lower temperature (< 100 oC) than its boiling point (usually in excess of 200 oC) by this method. Can only be used where significant amounts of oil are present and if the oil is not easily oxidised/hydrolysed. (See handout on Moodle for diagram of apparatus and collecting vessels for oils lighter and heavier than water.)

(Note: Some oils are glycosides and these need to be hydrolysed [enzymatically or using mineral acid] before under taking distillation.)

2. Expression (Pressure): This is a process by which oils are obtained by applying pressure (e.g. lemon oil BP). Machines called ‘sfumatrice machines’ are available but the quality of the oil is inferior to that produced by the ‘hand method’. With the latter method there is very little contact with the albedo layer, which contains enzymes that can degrade the oil.

Question 25

What does rectification of oils mean?

Answer 25

It is the purification of oil after recovery by a second distillation.

Question 26

List two examples of oil Rectified?

Answer 26

Turpentine and Caraway

Question 27

State the physical properties of volatile oil?
mention 8

how should it be stored?

Most are optically active (evaluation.
e.g.___________ is (−); synthetic is a racemic mixture ___________ is (+); synthetic is a racemic mixture

Answer 27

1 . Usually colorless when freshly prepared, but tend to oxidize and darken in color on standing. Store in a cool dry place, tightly stoppered, amber glass container and kept full if possible.

2. Insoluble in water, but sufficiently soluble to impart an aromatic odor to water (aromatic waters).
3. Soluble in most common organic solvents e.g. ethanol, CHCl3, and ether.
4. Usually lighter than water; exceptions are clove and cinnamon oils.
5. Have characteristic odors (evaluation).
6. Have high refractive indices (evaluation).
7. Most are optically active (evaluation.
   e. g. natural menthol is (−); synthetic is a racemic mixture natural camphor is (+); synthetic is a racemic mixture
8. Do not leave a permanent translucent stain on the paper.

Question 28

Peppermint oil BP is obtained from ………………….

Answer 28

the dried leaves and flowering parts of

Menthae piperitae.

Question 29

Know the following about Peppermint Oil

The plant is cultivated and contains ___________ by dry weight.
The oil is isolated by ______________

__________is composed of menthol and the rest is made up by __________________

Quality of the oil is influenced by ___________. Good quality
oil needs______________. Younger plants
contain predominantly a compound called ______________. The oil is characterized by _____________

Menthol has been credited with a pharmacological basis, it activates the ____________; cold and menthol receptor 1; CMR1) which than causes depolarization of sensory nerves resulting in an _______________________

Answer 29

The plant is cultivated and contains 1 % volatile oil by dry weight.
The oil is isolated by steam distillation.

50% of the oil is composed of menthol and the rest is made up by acetate of menthol, menthone, and other monoterpenes.

Quality of the oil is influenced by the age of the plant and seasonal variation. Good quality
oil needs a large proportion of esters and ketones (menthone and Jasmone). Younger plants
contain predominantly a compound called (+)-pulegone. The oil is characterized by gas
chromatography in the BP.

Menthol has been credited with a pharmacological basis, it activates the TRPM8 receptor (Transient receptor potential cation channel subfamily M member 8; cold and menthol receptor 1; CMR1) which than causes depolarization of sensory nerves resulting in an antitussive effect, mild anesthesia, and a cool feeling.

Question 30

State the uses of Peppermint Oil

Answer 30

the oil is used as a flavoring and finds considerable use in confectionary
Clinical uses include as a carminative in antacid preparations (e.g. Gelusil and Bisodol),
and also recommended for controlling symptoms of IBS.

Question 31

Eucalyptus oil is obtained from?

Answer 31

by steam distillation of the fresh leaves of Eucalyptus globulus

Question 32

Eucalyptus oil is often rectified and contains more than _____________
Identification test for the oil is based on a _____________

Answer 32

70% cineole (eucalyptol).

TLC method.

Question 33

State the Uses of Eucalyptus Oil

Answer 33

In inhalations and lozenges as a decongestant.

The oil is antiseptic and an insect repellent

Question 34

The main monoterpenes found in Tea tree oil is known as?

It has been shown to have activity against______________
(including _______) and as well as yeasts such as _________-. Other compounds that have been shown to have similar activity and are also present in the oil are _________, ___________ and _____________.

Answer 34

Terpinen-4-ol.

It has been shown to have activity against a number of bacterial species
(including Gram-negative) and as well as yeasts such as Candida albicans. Other compounds that have been shown to have similar activity and are also present in the oil are α-terpinenol, γ- terpinene and linalool.

Question 35

State the Uses of Tea tree Oil

hint 6 in number

Answer 35

formulated in many types of preparations for acne, sore throat, thrush, scabies, lice, and skin infections.

Question 36

Clove oil is obtained from?

The flower buds contain_______________

how is it extracted?

Answer 36

the dried flower buds of Syzygium aromaticum. The flower buds contain 14-20 % volatile oil (steam distillation).

Question 37

The main compound found in Clove oil is …….

Answer 37

Eugenol (90 %).

Eugenol (4-allyl-2-methoxyphenol) is a phenylpropane derivative.

Question 38

An example of an irregular Monoterpenes is called?

Answer 38

Valerian (Valeriana officinalis)

Question 39

Facts about Irregular Monoterpenes (Iridods)

___________of the valerian plant has traditionally been used for __________ and for ________________. It contains a number of closely
related structures to _______.

Concentrate on the ___________leaving out the___________ = iridane ring system which is an irregular monoterpene. See Slide 15

These compounds are thought to be responsible for ___________.

Some studies have shown that extracts of the plant do have ________ and can help ___________. However, evidence is required to be backed by clinical trials.

Answer 39

Root of the valerian plant has traditionally been used for anxiety type conditions (sedative) and for insomnia. It contains a number of closely
related structures to valtrate.

Concentrate on the middle ring structure leaving out the ester groups = iridane ring system which is an irregular monoterpene. See Slide 15

These compounds are thought to be responsible for the biological activity.

Some studies have shown that extracts of the plant do have a calming effect and can help short term insomnia. However, evidence is required to be backed by clinical trials.

Question 40

List other examples of volatile oils

Answer 40

Fennel, dill, cinnamon, and aniseed (carminative), citronella (insect repellent), juniper and pine (antiseptic), and turpentine (chemically converted to many other compounds).

Question 41

Uses of clove oil

Answer 41

has analgesic/antiseptic properties and is used as a tooth tincture. Purified eugenol is synthetically converted to vanillin (compare structures). The antiseptic properties has inclined it to be used in dentistry as a component of a cement containing zinc oxide for temporary sealing of cavities or as a base for tooth fillings.

Question 42

water distillation cannot be used for ___________________

Answer 42

Cannot be used for oils that decompose easily.

Question 43

steam distillation can only be used for __________

Answer 43

Can only be used where significant amounts of oil are present and if the oil is not easily oxidised/hydrolysed.

Question 44

in steam distillation, Machines called ______________ are available but the quality of the oil is inferior to that produced by the ‘hand method’.

Answer 44

‘sfumatrice machines’

Question 45

what should be considered in distillation

Answer 45

Some oils are glycosides and these need to be hydrolysed [enzymatically or using mineral acid] before under taking distillation.