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Flavonoids

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By : - Jaspreet Rekhi www.rhombnet.com www.ppt.rhombnet.com The flavonoids are polyphenolic compounds possessing 15 carbon atoms; two benzene rings joined by a linear ... – PowerPoint PPT presentation

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Title: Flavonoids


1
By - Jaspreet Rekhi www.rhombnet.com
www.ppt.rhombnet.com
2
Flavonoids
  • The flavonoids are polyphenolic compounds
    possessing 15 carbon atoms two benzene rings
    joined by a linear three carbon chain having the
    carbon skeleton C6 - C3 - C6 and they are the
    plant pigments and they are having polar in
    nature and solouble in methanol and water.
  • Flavonoids constitute one of the most
    characteristic classes of compounds in higher
    plants. Many flavonoids are easily recognised as
    flower pigments in most angiosperm families
    (flowering plants).
  • However, their occurence is not restricted to
    flowers but include all parts of the plant.
  • They are secondary mettabolite and effective in
    CNS disorders.

3
Tests for flavonoids
  • The extracts were dissolved in ethanol, filtered
    and subjected to following tests.
  • Shinoda test The dried extracts were dissolved
    in 95 ethanol (5ml) and few drops of
    concentracted hydrochloric acid (HCL) were added.
    Then the magnesium turnings were put into the
    solution and observed for appearance of pink
    color.
  • Lead acetate solution test To small quantity of
    above residue, lead acetate solution was added
    and observed for appearance of formation of
    yellow colored precipitates.

4
The Most Important Classes of Flavonoids and their Biological Significance The Most Important Classes of Flavonoids and their Biological Significance The Most Important Classes of Flavonoids and their Biological Significance
class number of known members biological significance (so far as known)
anthocyanin(s) 250 red and blue pigments
chalcons 60 yellow pigments
aurones 20 yellow pigments
flavones 350 cream-coloured pigments of flowers
flavonols 350 feeding repellents (?) in leaves
dihydrochalcons 10 some taste bitter
proanthocyanidins 50 astringent substances
catechins 40 some have propertieslike those of tannins
isoflavonoids 15 oestrogen effect, toxic for fungi
Flavonoids
  • Polyphenolic compounds with 15 C atoms, 2
    benzene rings on linear 3 C chain
  • Over 4,000 flavonoids
  • Easily recognized as flower pigments in most
    angiosperm plants but are not always flower
    pigments
  • In plants they repair damage and shield from
    environmental toxins

5
Core structures and nomenclature
  • The nomenclature of flavonoids proper is
    straight-forward with the aromatic ring A
    condensed to the heterocyclic ring C and the
    aromatic ring B most often attached at the C2
    position. The various substituents are listed
    first for the A and C ring and - as primed
    numbers - for the B ring (note that the numbering
    for the aromatic rings of the open-chained
    precursor chalcones is reversed).
  • (Harborne JB, ed. (1988) The Flavonoids. Advances
    in Research. Chapman Hall.)


Flavonoids
Society For Free Radical Biology and Medicine
W. Bors et al. .5
6
Flavonoids there example
  • Flavone- Luteolin, Apigenin, Tangeritin
  • Flavonol- Quercetin, Kaempferol, Myricetin,
  • Fisetin, Isorhamnetin,
  • Pachypodol, Rhamnazin
  • Flavanone- Hesperetin, Naringenin,
  • Eriodictyol,
    Homoeriodictyol
  • Flavanonol- Taxifolin, Dihydrokaempferol

7
Other flavonoids
  • CHALCONE
  • Chalcone is derived from three acetates and
    cinnamic acid as shown below.
  • Anthocyanidin is an extended conjugation made up
    of the aglycone of the glycoside anthocyanins.
    Next to chlorophyll, anthocyanins are the most
    important group of plant pigments visible to the
    human eye.

8
  • The anthocyanodins constitute a large family of
    differently coloured compounds and occur in
    countless mixtures in practically all parts of
    most higher plants. They are of great economic
    importance as fruit pigments and thus are used to
    colour fruit juices, wine and some beverages.
  • The anthocyanidins in Hydrangea, colours it RED
    in acid soil and BLUE in alkali soil.

9
ISOLATION OF FLAVONOIDS
Ground plant material
  • Maceration (3 times)
  • Purification with Chloroform (3 times)
  • Dropwise addition of 10 NACL solution
  • and centrifugation

Aqueous layer
Aqueous layer
Flavonoids in supernant liquid
Precipitate of tannins
Partioning with ethyl acetate
Flavonoid obtained by evaporation of
ethylacetate layer
10
Flavonoids
  • Act like antioxidants. How effective they are
    depends on their molecular structural
    characteristics
  • Some flavonoids in hops and beer have been
    found to have better antioxidant effects than tea
    or red wine most flavonoids are found in fruits,
    vegetables, teas, and other drinks.
  • Flavonoids have been known to have antiviral,
    anti-allergic, antiplatelet, anti-inflammatory,
    antitumor and antioxidant activities

11
  • Many flavonoid containing plants are
  • Diuretic.
  • Antispasmodic.
  • Diaphoretic.
  • Increase tensile strength of capillary walls.
  • Free radical scavengers.

12
Thanks for downloadingDo Comment plz.
By - Jaspreet Rekhi www.rhombnet.com
www.ppt.rhombnet.com
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