Topic 10 - The major groups of polyketides and terpenoids Flashcards Preview

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Flashcards in Topic 10 - The major groups of polyketides and terpenoids Deck (25)
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1
Q

Polyketides

A

Highly unstable → ring closing reaction → aromatic rings

2
Q

Specific polyketides

A
  1. Phloroglucinol derivates (e.g. humulone) – various effects
  2. Anthraquinones (e.g. emodin) – laxative
  3. Napthodianthrones (e.g. hypericin) – photosensitization
3
Q

Polyenes

A

Fatty acid metabolism saturated and unsaturated fatty acids polyenes

Alternating single and triple bonds

In fungi and plants (Apiaceae)

Herbal toxins affect the CNS

Brightly coloured

4
Q

Monoterpenes

A

Widespread in plants

Volatile compounds in oils

Acyclic, monocyclic (limonene in citrus fruits) and bicyclic (pinene in tansy) molecules and their derivatives

Monoterpenes often produce odour

They are rarely accumulated tissues

5
Q

Monoterpenes effects and functions

A

o Allelopahtic effect
o Insect repellent effect (menthol, myrcene, camphor)
o Pollinator attractants (pinene, eycalyptol)
o Antimicrobial antifungal effect (carvacol)
o Toxic effects (pinene)

6
Q

Iridoids

A

Non-volatile monoterpene derivative

♣ Protective chemicals (microbes, fungi, herbivores in the form of glycosides)
♣ The flavor of iridoids is distinctly bitter
♣ Medicinal effects: sedative, anti-inflammatory, antibacterial

7
Q

Pyrethrines

A

Non-volatile monoterpene derivative

♣ Insecticidal activity by targeting the nervous system used against parasites

8
Q

Sesquiterpenes

A

Natural occurrence mainly in Asteraceae family

Acyclic or cyclic compounds

Can be present in volatile oils, but less volatile than monoterpenes

9
Q

Effects of sesquiterpenes

A

o Apetizing effect
o Antispasmodic
o Painkillers, but allergic reaction and photosensitization is also possible

10
Q

Diterpenes

A

More then 2000 different molecules

Apolar or semi polar non-volatile compounds

Plant hormones: regulate growth and development – gibberellic acid

Poisonous derivates with nitrogen heterocycles pseudoalkaloids (taxines, aconitine)

Irritative effect, tumour promoters (phorbol)

11
Q

Medicinal effects of diterpenes

A
o	Spasmolytic
o	Cytostatic compounds
o	Anti-bacterial 
o	Anti-fungal and anti-inflammatory activity 
o	Cardioactive effects
12
Q

Bitter substances

A

Not a single biosynthetic group

Stimulate taste receptor → increased production of saliva and gastric juices

The bitterness value is the reciprocal of the dilution of a bitter compound. It is determined by comparison with quinine hydrochloride (bitterness value 200 000)

13
Q

Bitter substances Terpenoid groups

A

Monoterpenoid derivates (secoiridoids)
♣ Gentiopicrin
♣ Oleuropein

Sesquiterpene lactons
♣ Artemisinin
♣ Parthenolide

Diterpenoids
♣ Ginkgolide

14
Q

Triterpenes

A
Triterpenoid saponins
Phytosterols
Cardiac glycosides
Steroidal glycoalkaloids
Steroidal saponins
15
Q

Saponins

A

Not a single biosynthetic group

Amphipathic glycosides - emulsifying effect

Sapo (in latin) = soap → produce foam in the rumen

16
Q

Triterpenoid saponins

A

Synthesised from squale, with five rings → bounds with sugar → saponin effect

Poisonous/antinutritive effects

Tetracyclic aglycon

Generally four ringed molecules

Dietry supplies

17
Q

Medicinal effects of triterpenoid saponins

A
Anti-: 
fungal
bacterial
inflammatory acitivity
tumor
viral activity

Immunostimulant

Adaptogen: stabilisation of physiological processes

Radioprotective: reduce the effects of radiation

Cholesterol lowering effects

18
Q

Other effects of triterpenoid saponins

A

Poisonous → cucurbitacins

19
Q

Ginsenosides

A

Steroid glycosides and triterpene saponins exclusively in Panax (ginseng) spp.

20
Q

Steroidal saponins

A

The glycon parts are mostly oligosaccharides

The aglycon part are spirostanol or furostanol

Cytotoxic and antifungal activity

Diosgenin – precursor of synthetic steroidal and anti-cancer drugs

21
Q

Cardiac glycosides

A

Aglycons bounds with specific sugar moieties → glycosidic form with saponin effect

Inhibition of the membrane bound Na+/K+ pump → irregular or slow heart beat

22
Q

Steroidal glycoalkaloids

A

Biosynthesised from cholesterol with a nitrogen heterocycles pseudo alkaloids

Bitter flavour

Toxic effects

23
Q

Tetraterpenes

A

Derived from two GGPP molecules

Carotenoid plant pigments – UV védelem

In chromoplastids of roots, flower and fruits

24
Q

Polyterpenes

A

Acyclic polymers containing a large number of isoprene subunits

Natural rubber in the latex of rubber tree

25
Q

Terpenoids

A
Monoterpenes
Sesquiterpenes
Diterpenes
Triterpenes
Tetraterpenes
Polyterpenes