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Bioactive molecules from plants
JOM

Plant and microbiol secondary
metabolites
• Fine chemicals industry processes
petrochemicals and materials from nature to
create useful chemicals that can be applied as
commodity chemicals, fine chemicals and
specialty chemicals
...

• Two types of compounds are identifiable in
plants: primary and secondary metabolites
...
Their role in
plant metabolism and structure are obvious
...

• Carbohydrates are direct products of photosynthesis through
the intervention of chlorophyll and sunlight
...
So together with
carbohydrates they are called primary metabolites
...

• They are not directly involved in any obvious function
for the organism
...

• Typical examples of secondary metabolites belong to
structural classes, terpenes, flavonoids, alkaloids that
we will see and some lipids etc
...
Secondary metabolites
• The groupings, primary and secondary are strictly
based on functionality or non-functionality
...
Some compounds may be primary
metabolites in one organism while similar ones are
secondary metabolites in the same organism
...

• Secondary metabolites are found in much less
quantities than primary metabolites
...


Terpenes
• These are organic solvent soluble compounds
that are structurally made in nature or
biosynthesised from repeating isoprene (2methylisobutadiene) units normally in a head
to tail fashion
...


Terpenes
•
•

•
•
•
•
•
•

Terpenes are classified according to the number of isoprene units that
constitute their structure
...

Sesquiterpenes (1 and ½ terpenes) have 3 isoprenes so they have 15 carbon
atoms,
Diterpenes have 4 isoprene units so they have 20 carbon atoms
...

Triterpenes have 6 isoprene units so they should have 30 carbon atoms
...

All the structural classes of terpenes have modification types- reduced
number of carbons, inclusion of oxygen functional groups (rarely other
heteroatoms) and carbon skeletal structural rearrangements
...

• They are widely found in plants as part of the
essential oils
...

• They are present in less than 1% dry organ weight
...

+

Monoterpenes contd
• Monoterpenes are found in essential oils as complex
mixtures of upto 50-60 different compounds
...

• The composition of essential oils may vary according
to season, growing conditions, even time of day
...


Turpentine
• Turpentine is a medicine obtained by steam
distillation of resin of certain pine trees
...

• Sometimes the vapor is inhaled to relieve
chest congestion
• In foods and beverages, distilled turpentine is
used for flavoring
...


Turpentine composition
• Turpentine is majorly composed of α-pinene,
β-pinene, camphene, p-cymene and
limonene
...

• The diluted form of Eucalyptus oil is taken orally for
pain and inflammation of the respiratory tract
mucous membranes, coughs, asthma, bronchitis,
sinus pain and inflammation and respiratory
infections
...


Eucalyptus oil uses
• Eucalyptus oil is also used as a fragrance in
perfumes and cosmetics and is found in
mouth washes, liniments, and ointments,
tooth pastes, cough drops, and lozenges
...


Eucalyptus oil
• Examples of eucalyptus oil monoterpenes

OH

OH

OH

borneol
a-terpineol

b-terpineol

Limonene

Anise oil, clove oil, Ocotea
• Anise seed produces fragrant oil with aromatic
compounds, anisaldehyde being the major
component
...
Methyl eugenol is a
pheromone which acts as an attractant of male
mango flies
...
Its oxidation yields piperonal
...


Aromatic monoterpene derivatives
• Aromatics
O CH

CHO

3

O

O H
O CH

3

CHO
O
O

O CH

O

3

A n is a ld e h y d e
a n e th o le

p ip e r o n a l
eu genol

O

c in e o le

s a f r o le

Industrial reactions on some
monoterpenes
• Acid catalysed hydration of α-pinene yields
terpineol which is the main constituent of
pine oil
...

H 2O /H +
+

OH

a-p in en e
terp in eol

lim on en e

Reactions contd
...

p y ro ly s is

OAc

OAc

+

g e ra n y l a c e ta te
lin a ly l a c e ta te

OH

OH

g e ra n io l
lin a lo o l (c o m p o n e n t o f ro s e o il)

Further transformation of Myrcene
• Myrcene products
1
...
NaOAc
3
...
It is used in cigarettes and other personal care
products
...

O
CHO

O

O

H+

Ionones

+

Pseudoionones

O

Pharmacological uses of
monoterpenes
- They can cross the blood brain barrier- due to their
lipophilicity and small size
...

- Terpene alcohols are potent anti-microbiols in
essential oils
...

- Linalool containing essential oils are good sedatives
and have spasmolytic and hypothermic effects , thus
effective with CNS problem treatments or
management
...

- Peppermint oil which is 50% menthol is an
excellent carminative and is administered for
irritable bowel syndrome
...


Terpene effects contd
...

- Geranial has sedative, anti-viral and anti-microbial
properties
...

- Monoterpene phenols are some of the most potent antimicrobiols and other effects
...

- Clove oil is an effective topical remedy for tooth-ache and a
powerful stimulant due to eugenol
...


CH3

OH
OCH3

OH

H3C

CH2

CH3

CH

Thymol

Eu

H2C

Eugenol

Sesquiterpenes
• Sesquiterpenes are made of 1 and ½
terpenes- 3 isoprenes
...
It has been used as a male
contraceptive in China with efficacy of about 99%
...
Embelin from
local Myrsinaceae is the latest candidate with
reversibility characteristic
...

O
O
O
O
A
la
n
to
la
c
to
n
e

P
a
r
th
e
n
o
lid
e

O

Artemisinin
• Artemisinin is a compound isolated from Chinese herb qing hao su or
Artemisia annua used for treatment of malaria
...
These
derivatives are constituted as ACTs with mefloquin, sulfadoxin
pyrimethamine, and lumefantrine
...
That is to increase availability
...

• Artesunate is water soluble
...

O
O

O

O

O

O

O

O
O

O
O

A rtem isinin

O
O

O

A rtem ether

O
O CH 3

H 2O

A rtesunate

N aO

O

Synthesis of artemether from
artemisinin
•
...
N aO M e
3
...


O

1
...
N aO M e
O
3
...

• They include the bitter principles of certain
plants
...

• Taxol and its derivatives are used as
prescription drugs for cervical, ovarian and
breast tumors
...


Paclitaxel or Taxol
•
...

• They control growth and development and maintain
immune system and good vision
...

• As retinoic acid it acts as hormone for epithelial cells
and other cells
...
It is found in corn oil,
soybean oil, margarine, and salad dressings
...
As a fat
soluble anti-oxidant, it stops production of reactive
oxygen species formed when fat undergoes
oxidation
...
K deficiency

Vitamin K
• This is a group of structurally related vitamins
the human body needs for synthesising
certain proteins involved in blood
coagulation and also for binding calcium into
bones
...
Vitamin K3 exhibits toxicity

Phytol
• Phytol is a diterpene alcohol which is needed
for the synthesis of vitamin E and vitamin K1
...


Phytol structure
•
...

R

HO
b-Amyrin R= CH3
Oleanolic acid R= COOH

Squalene (Shark oil)

C-27 derivatives
• The principal derivatives of plant triterpenoids are C-27
compounds such as saponin steroids and other steroids
...
Most saponins are derivatives of oleanolic acid
...
They are found in
cell membranes to maintain membrane fluidity and to act as
signalling compounds
...
g
oleanolic acid) or steroidal (e
...

• They lather on shaking in water because they
lower surface tension like soap
...
They also cause haemolysis
of red blood cells
...

• Diosgenin and other saponins from Dioscorea
species are used as raw materials for the production
of various synthetic and semi-synthetic steroidal
drugs such as fertility regulator drugs menstranol,
sex hormones and anti-inflammatory drugs
...

• These are usually hooked to sugars such as glucose,
rhamnose and digitoxose in the glycosidic forms
...
For example
it is converted to progesterone in the manner shown
...
H 2 /P d

2
...
A l (O is o p r o )3
/A c e to n e

O
P ro g estero n e

Biosynthesis of steroid ring system
• Steroidal saponins are derived in nature from
Squalene through lanosterol

E
poxidation

H
O
/E
poxidase

L
anosterol

Squalene

H
O
C
holesterol

Steroids
• Many drugs for human and veterinary animal use are
steroids
...

• Cholesterol is the most common alcohol found in
animal tissues
...

• Steroidal hormones have many functions- anabolism,
sex hormones, anti-inflammatory agents and oral
contraceptives
...
They are popular with body builders
...

• Typical examples are stanozol and nandolone
...

O
H

O
H

H
H
N
N
H
s
ta
n
o
z
o
lo
l

H H

H H
H

H H
O
n
a
n
d
r
o
lo
n
e

Adrenal cortical steroids
• Adrenal cortical steroids include cortisone,
cortisol, and aldosterone
...

• The first two are applied as anti-inflammatory
agents but also regulate carbohydrate
metabolism in the body
...


Adrenal cortical steroid structures

O
O

CH2OH
OH

O
HO

CH2OH
OH

HO O
O

O
cortisone

O

O
cortisol

aldosterone

CH2OH

Bile acids
• These include cholic and deoxycholic acid
which have a C5 chain at position C-17 which
ends in a carboxylic acid group
...

O
H
O
H
H

C
O
O
H
H

H
O

H
C
holicacid

H

O
H
H
O

H
D
eoxycholicacid

C
O
O
H

Human reproductive hormones
• Mammalian sexuality is influenced by various
steroidal hormones which are secreted by the
testes or ovaries
...


Human reproductive hormones
contd
...

• The principal hormone responsible for
secondary sexual characteristics development in
the male is testosterone while in females they
are progesterone, estrone and estradiol

Sexuality hormones
• There are two types of female sex hormones,
estrogens and progesterone
...
They
stimulate ovulation while progesterone
maintains the fetus in the uterus by ensuring
adequate blood is supplied to the uterus and
that adequate nutrients and oxygen are
delivered to the fetus throughout pregnancy
...

O
OH
H
H

H

H
H
H

H

H

HO

O

Testoterone

Androsterone



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