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1. Flavones & Flavonoids
Presented by:
Hadeel Fawzi Hammad

2. (1) Flavones

3. Occurrence:
• Flavones from plants are typically
conjugated as 7-O-glycosides.
• flavones exist in dried tea leaves,
herbs, fruits, vegetables, olive oil,
honey, cereals and legumes.

4. Synthesis:
• Using O-benzoyloxyacetophenone.

5. Synthesis:
• using palladium (II) acetate catalysed reaction

6. Reactions:
• 1,2-Cycloaddition of diphenylacetylene and flavone.

7. Reactions:
• Photo-oxidative cyclization of 3-methoxyflavones

8. Applications:
• Have more applications as textile dyes.
• UVB protection ability.
• Yellow colorants in fabrics.
• Have higher light and thermal stability.
• Used as a pigment.
• Anti-inflammatory.
• Anti-allergic.
• Antiviral.
• Antioxidant.
• Antitumor.
• Used for multi-targeting in complex diseases like cancer, inflammation,
cardiovascular disease and diabetes.

9. (2) Flavonoids

10. Occurrence:
 Flavonoids are an important class of natural
products.
 Their basic structure is a skeleton of
diphenylpropane
 They belong particularly to a class of plant
secondary metabolites having a polyphenolic
structure, widely found in fruits, vegetables and
certain beverages.

11. Classification:
Flavonoids can be subdivided into different subgroups depending on the
carbon of the C ring on which the B rings attached and the degree of
unsaturation and oxidation of the C ring.
Flavonoids in which the B ring is linked in position 3 of the C ring are called
isoflavonoids.
Those in which the B ring is linked in position 4 are called neoflavonoids.
While those in which the B ring is linked in position 2 can be further
subdivided into several subgroups on the basis of the structural features of
the C ring. These subgroups are: flavones, flavonols, flavanones, flavonols or
catechins, anthocyanins and chalcones.

12. Classification:
1- Isoflavonoids :-
 Flavonoids in which the B ring is linked in position 3 of the C
ring.
 Isoflavonoids are a large and very distinctive subgroup of
flavonoids.
 Isoflavonoids enjoy only a limited distribution in the plant
kingdom and Some isoflavonoids have also been reported to
present in microbes.
 Examples: Soyabeans and other leguminous plants.

13. Classification:
2- Neoflavonoids :-
 Flavonoids in which the B ring is
linked in position 4.
 While flavonoids have a 2-
phenylchromen-4-one backbone,
neoflavonoids have a 4-
phenylcoumarine backbone.

14. Classification:
3- Subgroups of flavonoids in which the B ring is
linked in position 2:-
I. Flavones:-
 Flavones are one of the important subgroups of
flavonoids.
 Flavones are widely present in leaves, flowers and
fruits as glucosides.
 Examples: Celery, parsley, red peppers, mint and
ginkgo biloba.

15. Classification:
ii. Flavonols:-
 Flavonols are flavonoids with a ketone group and they have a
hydroxyl group in position 3 of the C ring.
 Flavonols occur abundantly in a variety of fruits and
vegetables.
 Apart from fruits and vegetables, tea and red wine are also
sources of flavonols.
 Examples: Yellow Onions, scallions, broccoli, tomatoes,
apples and berries.

16. Classification:
iii. Flavonones:-
 Flavanones are another important class
which is generally present in all citrus
fruits. These compounds are responsible
for the bitter taste of the juice and peel of
citrus fruits.
 Flavanones also called dihydroflavones,
they have the C ring saturated unlike
flavones, the double bond between
positions 2 and 3 is saturated
 Examples: Oranges, lemons and grapes.

17. Classification:
iv. Flavanols:-
 They are called flavanonols, flavan-3-ols or
catechins.
 Flavanols are referred to flavan-3-ols as the
hydroxyl group is always bound to position 3 of the
C ring.
 They are also called dihydroflavonols or 3-hydroxy
derivatives of flavanones.
 Examples: Bananas, blue berries, peaches, apples
and pears.

18. Classification:
v. Anthocyanins:-
 Anthocyanins are pigments responsible for
colours in plants, flowers and fruits.
 They occur predominantly in the outer cell
layers of various fruits.
 Examples: Grapes, strawberries, Plum,
blue berries and black berries.

19. Classification:
vi. Chalcones:-
 They are characterized by the absence
of ring C of the basic flavonoid skeleton
structure.
 They can also be referred to as open-
chain flavonoids.
 Examples: tomatoes, pears,
strawberries and certain wheat
products.

20. Applications:
• Reduction in blood pressure due to its vasodilatory effect.
• Reduced risk of cardiovascular diseases.
• Inhibits platelet aggregation.
• Inhibits LDL oxidation by free radicals.
• Delays or prevents the onset of diseases caused by free radicals.
• Anti-inflammatory.
• Antiviral.
• Antioxidant.
• Antibacterial.