Terpenes and Terpenoids

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Transcript Terpenes and Terpenoids

Terpenes and Terpenoids
Terpenes - class of >20,000 compounds containing
carbon atoms in multiples of five
Terpenoids - oxygen-containing terpenes (alcohols,
ketones, aldehydes)
The name "terpene" is derived from the word "turpentine" (terebentin-reçineden elde edilir)
Terpenes and terpenoids are the primary constituents of the essential oils of many types of
plants and flowers. Essential oils : bitkilerdeki sellüloz ve nişasta dışındaki çoğu kez uçucu olan
belli bir tad/kokuya sahip bileşikler)
rose oil
(zencefil)
(kereviz)
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The basic molecular formulae of terpenes are multiples of that, (C5H8)n where n is the number
of linked isoprene -Isoprene - 2-methyl-1,3-butadiene- units. This is called the isoprene rule or
the C5 rule.
Compounds containing carbon atoms in multiples of 5 suggest a C5 building block - isoprene
units linked in a “head-to-tail” fashion
Ancak unutulmamalıdır ki moleküller büyüyüp halkalaştıkça biyosentezler başkalaşmalara yol
açabilirler. Retrosentezlerle başa gidilir.
2-methyl-1,3-butadiene
“Head” - branched end of isoprene
“Tail” - unbranched end of isoprene
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Finding the isoprene building block - cyclic compounds
Finding the isoprene building block - sesquiterpenes (C15)
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Finding the isoprene building block - triterpenes (C30) -
Squalene has a natural and vital part in the synthesis of all plant and animal sterols, including
cholesterol, steroid hormones, and vitamin D in the human body
Finding the isoprene building block - tetraterpenes (C40)
Lycopene's eleven conjugated double bonds give it its deep red color and are responsible for its antioxidant activity.
Lycopene is responsible for the red color in tomatoes and watermelon
-carotene is the compound that causes carrots and apricots to be orange
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Biosynthesis of Terpenes
Biological “isoprene” - isopentenyl pyrophosphate (3-methyl-3-butenylpyrophosphate).
Enzimlerle izomerizasyona uğrar. İzomerizasyon ürünü yeni bir isopentenilpirofosfat ile
reaksiyonda monoterpen içeren pirofosfat türevi oluşturur. Bu son türev doğal koşullarda ester
hidrolizine uğrar ve bir terpenoid olan geraniol ü verir.
Aldol cond
SN2
Enzimle hid.
Tioesterden alkole
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Isopentenyl pyrophosphate is only one of the necessary reagents for the biosynthesis of terpenes…
dimethylallyl pyrophosphate, a C5 isomer, is also necessary:
Add. of H+
elimination of a proton
RULE - isopentenyl pyrophosphate and dimethylallyl pyrophosphate are the C5 building blocks for the
biosynthesis of terpenes
Elimination of a proton from a carbocation intermediate generates a double bond (E1 reaction)
Geranyl pyrophosphate - C10 building block for many biological monoterpenes
Geranyl pyrophospate ester hid ile geraniol verir.
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humulene
found in the essential oils of Humulus lupulus
Hemiterpenes consist of a single isoprene unit. Isoprene itself is considered the only hemiterpene,
but oxygen-containing derivatives are hemiterpenoids such as prenol (found in citrus fruits, cranberry, grapes,
raspberry, blackberry, tomato, white bread…)
and isovaleric acid (found in in essential oils).
Monoterpenes consist of two isoprene units and have the molecular formula C10H16. Examples of
monoterpenes are: geraniol, limonene and terpineol.
Sesquiterpenes consist of three isoprene units and have the molecular formula C15H24. Examples of
sesquiterpenes are: humulene, farnesenes, farnesol.
limonene
a strong smell of oranges
Prenol
isovaleric acid
terpineol
found in pine oil
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Diterpenes are composed of four isoprene units and have the molecular formula C20H32. Examples
are cafestol, kahweol, cembrene and taxadiene (precursor of taxol). Diterpenes also form the basis for
biologically important compounds such as retinol, retinal, and phytol. They are known to be antimicrobial
and antiinflammatory.
Retinol is one of the forms of vitamin A
Taxadiene from enzymes
taxol used in cancer chemotherapy
Pasifik porsuk ağacı kabuklarından
Sesterterpenes, terpenes having 25 carbons and five isoprene units, are rare relative to the other sizes.
An example of a sesterterpene is geranylfarnesol.
Triterpenes consist of six isoprene units and have the molecular formula C30H48. The linear
triterpene squalene, the major constituent of shark liver oil.
Tetraterpenes contain eight isoprene units and have the molecular formula C40H64. Biologically important
tetraterpenes include the acyclic lycopene, the monocyclic gamma-carotene, and the bicyclic alphaand beta-carotenes.
Polyterpenes consist of long chains of many isoprene units. Natural rubber consists of polyisoprene in
which the double bonds are cis.
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Terpenler HALKA SAYISINA göre de sınıflandırılabilirler:
Asiklik, monosiklik, bisiklik, trisiklik… (2Z)-3,7-dimethyl-2,6-octadien-1-ol
Terpenlerde isimlendirme: IUPAC kuralları yanısıra özel okumalar da söz konusudur.
Asiklik terpen örnekleri:
8
7
8
7
CH2OH
4
1
3
Kuyruk 4
baş
3
7-methyl-3-methyleneocta-1,6diene
Mirisen
(trans)-3,7-Dimethyl-2,6-octadien-1-ol
Ald turevi citral-a
(2Z)-3,7-dimethyl-2,6-octadien-1-ol
Ald turevi citral-b
from parsley..
Monosiklik Monoterpen örnekleri: menthol
Thymol
menthol
Carvone
Kimyon yağı
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Bisiklik terpenlerin IUPAC okunması:
1
4
6
3,7,7-trimethylbicyclo[4.1.0]hepta-3-ene
1-metil-7-metiliden-4-izopropiliden bisiklo[4.4.0]dekan
2,6,6-trimethylbicyclo[3.1.1]hepta-2-ene
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